Occupational Skills

• ignition point is the lowest temperature at which fuel will spontaneously ignite
• range of flammability refer to th range of fuel/air mixtures through which a fuel will burn
• torque to yeild: torque to spec, rotate a specified degree

Oxygen

• oil and gease exposed to pure oxygen under pressure can self-ignite
• full filled @ 2175psi - 15000 kPa
• frangible disk will rupture at 3200psi and discharge the whole contain of the cyclinder
• has right hand thread to connect to a regulator
• the oxygen valve MUST always be fully open to prevent leakage around the stem of the valve because of oxygen cylinder valve is a double seated valve
• oxygen cylinder can be used in any position

Acetylene (2~89%)

• Pure C2H2 have a maxium stable pressure 15psi
• @ 28psi and 21C acetylene will be self-ignite
• by using porous filler and liquid acetone, cylinder pressure can be at 250psi safely
• acetylene cylinder must be used in upright position to prevent acetone from being drawn off
• draw limit should be no faster than 1/7 of its cap per second
• has left hand thread to connect to a regulator
• the acetylene valve usually opened no more than one turn

Propane (2.4~9.5%)

• C3H8 is heavy than air, will accumulate in low-lying areas
• propane valve has a small tube which make sure that propane cylinder always charge @ 80% its cap
  • if liquid propane is in contact with the underside of the tube, liquid propane is expelled to the atm

Regulator

• single-stage regulator
  • only 1 metering needle
• two-stage regulator
  • 2 metering needle
  • have intermediate pressure cavity
  • provide more consistent delivery flow and pressure

Tip

• larger number, large tip, sized from 00 0 1, to 10
• multi-flame or rosebud tip, sized from 2 to 8

Hoses

• mimum support 400psi pressure
• oxygen hose: right hand thread, green
• acetylene hose: left hand thread, red, an annular groove is cut in the hexagonal of the fitting

Flashback arrestor or check valves

• prevent mixing of the acetylene and oxygen in the hoses or regulators
• oxygen and acetylene flashback arrestor are marked to differentiate

Flame type

• acetylene flame: open torch handle acetylene valve - yellow 800C
• carbonizing flame: add oxygen - charaterized by white feather flame 3000C
• neutral flame: increase oxygen, and decrease acetylene until the white feather disapear, recommended for cutting and heating
• oxidizing flame: excess oxygen, has shorter, shaper, paler blue than neutral flame

Oxyacetylene usage procedure

Set up

• secure the cylinder to a cart or wall, uncap, check all fitting and remove oil
• crack cylinder valves one at a time to purge dust and dirt
• attach pressure regulator to the cylinders and tighten the fittings
• attach the hoses to the regulators, check valves, and torch handle
• relase the regulator adjusting screws and open the cylinder valves slowly (oxygen fully open, and acetylene no more than one turn)
• close torch valve, adjust acetylene and oxygen to 5psi, check for leaks
• crack torch valve one at the time to purge all foreign gases

Shutdown or turning off the torch

• close the oxygen cylinder valve
• open the torch oxygen valve to release pressure
• turn oxygen regulator adjusting screw out to free position
• close the torch handle oxgen valve
• repeat same steps for acetylene

Torch pressure balancing

• evertime the tip is changed, the torch must be re-balanced
• slowly crack the open oxygen cylinder valve, then open to the full position
• open the acetylene cylinder valve no more than 1 turn
• purge each hose individually with regulator @ 5psi
• set 2-3 psi on each regulator
• open the acetylene torch valve 1/4 turn, then ignite the torch with striker
• fully open the acetylene torch valve (~2 turns)
• increase the acetylene pressure with the regulator screw to apoint where the flame leaves the tip (blow off)
• back off the acetylene torch valve until the flame return to the tip and burn smoke free
• fully open the oxygen torch valve (~2 turns)
• fully open the acetylene torch valve
• with both torch valves wide open, adjust the oxygen pressure regulator screw to obtain a neutral flame

Backfire

• backfire occurs when the flame backs up into the tip and mixer, loud pop, not serious malfunction
• following conditions cause backfire:
  • too slow gas flow, not open the acetylene torch valve enough
  • obstruction air flow, holding the torch tip too close to the work, dirty tip
  • loose or faulty connection bw the tip and the mixer
  • hot tip can be caused by working in deep grooves or blind holes, can cause series of rapid backfires
    • to cool hot tip, close the torch valves, quench in water

Air brake

Governor

• RES: sense the supply tank
• UNL: use air from RES port to unloading compressor and trigger exhaust in air dryer
• EXH: exhaust air from unloader lines in load cycle

Air Dryer

• UNL: sensing line from unloader port of governor
• COMP: air from compressor
• RES: to supply tank

Air brake circuit

• primary service circuit: rear brakes
• secondary service circuit: steers axle brakes (front)

• emergeny brake circuit

• DC-1 double check valve, which pressure from what ever high pressure
• PP-1
• R-14: speed up application, and quick release brake
• SR-1: spring brake valve (modulate about 5 times) help if rear axles tank lost pressure
  1. primary reservoir port
  2. control port (air application, blue)
  3. mix air
  4. to brake relay
• red glad hand : trailer supply
• blue glad hand : trailer service
• tractor protection systems
  • TP-3 tractor protection valve, on/off for service line
    • tractor supply
    • tractor service
    • trailer supply
    • trailer service
    • 45 psi on tractor supply side will allow service brake
  • PP-7 trailer supply valve (red button)
    • supply port: from double check valve
    • delivery port: to tractor supply port of pp-3
    • control port: from delivery port of pp-1
    • exhaust port
    • pop out if air drop below 40 psi

      Trailer valves

• trailer release valve (syncro valve)
  • use to delay supply air to pup trailer until the lead trailer supply pressure exceed the valve setting 60-86psi
  • this avoid to hold the trailer supply valve button in to charge trailers

Coupling units

Fifth wheel coupling

• rated by based on
  • tow vehicle weight
  • maximum expect drawbar load
  • vertical load to be carried by fifth wheel
  • type of operation
• types: stationary and sliding
• after hooking up to a tractor, there should be no gap bw top plate and trailer king pin

Pintle hitches

• pindle hook
  • rigid type, use pin to lock the assembly
• draw bar and eye
  • has air chamber, push rod, and shoe
  • designed to remove any clearance bw the hook and the trailer drawbar
  • latch and locking pawl prevent the draw bar eye from jumping out of the hook
• safety chains and hardware

Engine fundamentals

• Force is the push or pull; lbs or N
• Work = force x distance; ft-lb; Nm
• Torque = force x distance; lb-ft; Nm
• Horse power is the amount of work done in a given period of time or the rate of doing work
  • 1 hp = 746W
  • 1 hp = 33000 lbs x 1 foot x 1 minute
  • 1 W = 1 Nm x 1 second
• CI: compression ignition refers to the method of igniting fuel in a diesel engine
  • diesel is injected into highly compressed air and the heat of compression ignites the fuel
• SI: spark ignition
  • electric spark is used to ignite an air/fuel mixture
• piston displacement is the swept volume of a single cylinder
  • piston displacement = cylinder area x stroke
• clearance volume (CV) is the volume remaining above the piston when it’s at TDC
• compression ratio = ( pistone displacement + CV ) / CV
• engine displacement is piston displacement x number of cylinders
• thermal efficiency is the ability of an engine to convert the heat energy of a fuel into useable heat energy
  • internal combustion engine is approximately 36%
• the camshaft of a four stroke cycle engine rotates at 1/2 crankshaft speed

Engine block

• frost plugs or expansion plugs which pop out if coolant freeze, to protect engine
• enbloc:
  • intergal cylinders
  • liners:
    • counterbore is a machined rescess in the block, where liner is seated
    • relief is cut under the flange, so the liner will fit into the block without interfering with the edge of the counterbore
    • dry: no contact with coolant
      • firewall is a raised rim above liner’s flange that reduce the combustion pressure, and heat act on the head gasket
    • wet
      • bead on the top of the flange cuts into the head gasket act as firewall
      • seal rings are used to prevent coolant from leaking into the crankcase
      • mid-stop design can eliminate the use of seal ring
    • air cool
• modular or sectional: stationary, big engine
• service:
  • crack dectection
    • dye check: cleaner, penetrant, developer
    • mage particle: ferrous metals only
    • pressure test (bring the block to operating temperature before testing)
  • deck surface flatness
    • use straight edge and a feeler blade (0.0015”)
    • measure 3 positions: 1 lenghthwise, 2 diagonally
    • maximum wrap 0.004”
  • main bearing bore alignment
    • use straight edge and a feeler blade (0.0015”)
  • main bearing bore size
    • use dial bore gauge or telescoping gauge with an outside micrometer
    • measure 3 position, subject the smallest from the largest diameter, compared to spec
  • camshaft bearing bore alignment
  • camshaft bearing bore size
  • thread repair
    • helicoil inserts
    • solid insert (stronger but have a larger outside diameter)
      • can have locking pin, which driven down to lock the insert from turning
  • cylinder measurement
    • use dial bore gauge or telescoping gauge with an outside micrometer
    • measure 4 locations
      • compare top and bottom to determine taper
      • compare inline 90% degree give out of round
  • boring oversize (intergal cylinder)
    • double taper wear, and user the nerxt largest piston oversize available
    • can use a repair sleeve
    • crosshatch need to be restore to retain oil for lubrication of the piston rings
    • clean water, detergent and a stiff bristle brush, DO NOT use solvent
  • liner
    • before remove, measure liner wear and liner height
    • store line vertically
    • remove by slide hammmer liner puller or a screw type liner puller
    • check for crack, scuffing (lack of lube, overheat), scoring (broken rings, foreign marterial
      • if the scoring catches finger nails, replace
    • measure liner flanges
  • counterbore
    • check for crack, erosion, and pitting
    • measure depth and flatness with depth micrometer or a sled gauge
  • liner height = flange thickness - counterbore height, compare with specs (should be positive, so liner flange sit above the block deck)
    • use shim if needed
  • installation
    • dry liner can be chill in dry ice to shrink the outside diameter for press fit
    • wet liner: lub seal ring with liquid soap or vegetable oil; DO NOT use pertro oil
    • use cylinder bore gauge measure again at the area of o-ring
      • out of round indicates o-ring is twisted
    • measure liner height again with a liner torque down

Cylinder heads

• number of valves

• ports are cast in the cylinder head to direct airflow in and out of the cylinder
• injector tube is a cylindrical sleeve made from copper, stainless steel, or brass; surround by coolant

• coolant directional nozzles are copper or brass inserts which direct coolant flow to critical areas like exhaust valve seats

• valve:
  • assembly: valve lock, valve spring retainer, valve spring, valve seal, valve spring seat, valve guide, valve face, valve seat
    • valve seat provides wear resistance, seal the valve closes, draw heat away from the valve face
  • terminology: tip, lock groove, stem, fillet, face, margin, head
  • carbon scraper helps keep the lower part of the valve guide clean and reduce carbon build up
    • the lower end of the valve stems are machined to a slightly smaller diameter
  • sodium-cooled exhaust valves has hollow valve stem filled with sodium crystals (15% cooler than solid one)
• valve guides & seats can be intergal or wearable insert
• valve face angle
  • intake has 30 degree angle providing better air flow
  • exhaust has 40 degree angle providing more seating force, thus keep the seat clean and better cooling
• valve spring
  • valve float happens when valve springs oscillate uncontrolled, which prevents the valves from sealing properly, resulting loss of power
  • constant rate spring has a constant rate of force
  • progressive spring has a variable rate of force increase as it’s compressed a specific distance
• valve retainers & locks
  • keep the valve and spring as a unit
  • can be called collects or keepers
• positive valve rotator
  • can be used in place of valve retainers or spring seat
  • change wear surface for even valve and seat wear
  • create a wiping action that clean the valve face and seat
• valve seal
  • help prevent oil run down bw valve guide and valve stem cause oil consumption and carbon build up in the ports, valves
  • inventually will reduce engine’s volumetric efficiency, then power loss can occur
  • positive seal provide the best control of valve stem lubrication; has spring clips to seal on valve stem
  • non-positive or umbrella type seal rides up and down with the stem during engine operation
• valve bridge or crosshead: allow 1 rocker open a pair of valves simultaniously

Cylinder heads service

• remove injectors, and glow plugs before removing the head
• valve leakage test:
  • rest the head on the bench with the head gasket surface vertical
  • fill the port with petroleum solvant and observe the valve/sear area for leakage
  • minor moistening is accpetable; stream of fluid is NOT ok
• pressure test to find internal cracks
  • using special test strips to seal all of the cylinder head coolant passages
  • if injector tubes is used, dummy injector will be used in place with the injector hold down crab
  • apply 20~40psi air pressure to the coolant passage
  • immerse the head in the hot water tank @ 180~200F for 15~20 minutes
• injector tubes and o-ring will be replaced during cylinder head rebuild
• cleaning: soaking the head in hot tank, followed by steam cleaning
• water passages deposits:
  • white scale - high concentration of minerals
  • green/blue - high concentration of cooling chemical
  • rust/corrosion - lack of corrosion inhibitors
• valve guide need to be clean by using valve guide brush or carbon scraper
  • measure diameter by a small hole gauge
  • worn valve guides cause:
    • accelerated wear of the valve face and seat
    • oil consumption
• after grind the valve, make sure the remaining margin greater than 1/2 the margin of new valve
  • insufficient margin will run excessively hot and burn prematurely
• service removable valve guide
  • use a hammer or air chisel and valve guide remover to remove the valve guide
  • use an air harmer, valve guide driver, and a limiting sleeve to install the new valve guide
    • limiting sleeve stop the driver when the guide reaches the correct depth
  • valve guide height
    • too high: component damage because of contacting between the valve spring retainer and the valve seal
    • too low: valve may not be closed because of contacting between the guide and the valve fillet
• service the valve insert
  • use ‘a valve seat insert puller’ to remove the valve seat
  • use a hammer and ‘a valve seat insert installer’ to drive valve seat to the head
  • finish by doing a concentricity check to ensure that the valve seat is concentric with the valve guide
• valve face and valve seat angles
  • can be slightly different 1/2 ~ 1° to produce a narrow contact between the valve face and seat
• valve seat width and contact area
  • firstly grind with 45° stone, secondly 15° stone, lastly 60° stone
  • spread a thin lay of Prussian blue on the valve face, insert the valve to the guide without spin the valve, remove and check the valve
  • the seat is too narrow, reducing contact area, poor cooling, and rapid wear
  • the seat is too wide, lower the seating force, causing leakage, carborn build up, then poor cooling
• valve seat height or protrusion is the distance from the bottom of the valve head to the machined gasket surface on the cylinder head
  • excessive height increase in compression ratio & piston can contact valve
  • insufficient height decrease in compression ratio
• valve spring service
  • free length measurement
  • squareness; maximum allowable variation 1/16”
  • tension: valve close height and tension; valve open height and tension
    • low tension cause poor valve sealing, cooling, valve flow or flutter
• once push rod has been bent, it is fatiqued and will be more susceptiable to bending; always replace bend push rods
• if valve face and seat has been machined, this increases the valve spring height and lowers the valve spring tension
  • install shims under valve spring; install no more than 2 shims, max 0.060”
  • use a vaccum tester apply 20” of Hg. A drop in vacuum greate 10 Hg in 10s is excessive
• torque cylinder head in sequene, starting from the center of the head and working outward
• torque and turn is more accurate than torquing a fastener to a final value
  • initial low torque values seats the mating surface, an turn the fastener produces a specific amount of bolt stretch for even clamping load
• install valve bridges before the rocker arm assemblies; guideless crossheads don’t use guide pin and non-adjustable
  • adjust crossheads, to open valves at the same time, and is centered on the guide pin
    • back off the adjusting screw off one turn (until it’s not touch the tip of the valve stem)
    • apply light finger pressure to the center of the crosshead and turn the adjusting screw down until it touches the valve stem
    • hold the adjusting screw and snug the lock nut, (some time, crossheads need to be holded upon torquing to prevent bending the valve stem)
• valve clearance (lash)
  • provide clearance for component expansion as engine temp rises
  • compensate for wear in the valve operating mechanism
  • the valves must be closed upon adjusting the valve lash
  • adjust the clearance
    1. insert the feeler gauge, tighten the adjusting screw until any clearance is removed
    2. continue to tight 1/4~1/2 of a turn to open the valve slightly and squeezes oil out of the operating mechanism contact areas
    3. back the adjusting screw off until the feeler gauge slide smoothly with a slight drag
    4. hold the screw and snug the locknut, then torque the locknut
    5. recheck the drag on the feeler gauge

Two stroke engine

• 360 degree of the crankshaft rotation to finish a cycle
• exhaust valves open @ 102 ATDC and close @ 60 ABDC
• intake valves open @ 46 BBDC and close @ 46 ABDC; during this time the exhaust valves are also open (scavenging)
• fuel is injected @ 21 BTDC
• scavenging is the removal of the exhaust gases from the cylinder
  • crankcase scavenging:
    • use in small gasoline engines; high exhaust emissions
    • air and fuel are pressurized in the crankcase by the downward movement of the piston
  • blower scavenging
    • use a possitive displacement air pump or blower to pressurized the inlet air
    • use in two stroke diesel engines

Four stroke engine

• 720 degree of crankshaft rotation to finish a cycle
• intake valves opens @ 20 BTDC and close @ 49 ABDC
• fuel is injected @ 23 BTDC, power stoke ends when exhaust valves are opened
• exhaust valves open @ 51 BBDC and close @ 20 ATDC
• valves overlap is when both intake and exhaust valves are opened at the same time.
  • the incoming boost air helps remove the exhaust gases (scavenging)

Gasoline vs diesel

• gasoline
  • intake: has air inlet restriction by a throttle valve
  • compression: air/fuel 9:1
• diesel
  • intake: completely fill cylinders with air even @ idle
  • compression: air/fuel 18:1 ~ 25:1

Piston, rings, and connecting rod

• piston material
  • cast iron
  • hypereutectic aluminum (higher silicon content)
• piston types
  • trunk type piston
  • two piece
    • crosshead design: uses semi-floating piston pin (pin is fixed to connecting rod)
    • articulated design: uses full floating piston pin (free to rotate in both the piston and the connecting rod, thus changing wear surface)
• tapered piston skirt
  • the piston skirt is generally tapered from the top to the bottom since the top of piston skirt is subject to higher temperatures
• cam ground piston skirt
  • the piston skirt of cam ground piston is an oval shape, measured slightly larger across the thrust faces
• piston skirt types: full, semi-slipper, slipper
  • to clear the crankshaft when the piston is approaching BDC
• ring groove insert
  • to reinforce & reduce wear in compression ring grooves
  • steel, nickle-chrome alloy
• piston cooling
  • splash
  • spray: medium & high speed engine
  • circulation: slow speed engine
  • shaker
• piston rings
  • form a gas tight seal by combination of cylinder pressure, ring tension and an oil film on the cylinder wall
  • cool the piston
  • control lubrication

Camshaft

• camshaft nose is located at front of camshaft, a mounting surface for drive gear
• journals are the load bearing surfaces
• lobes are accentrics that convert the rotary motion of the camshaft into reciprocating motion of the cam follower
• modular camshafts are used in big engine
• OHV: overhead valve or camshaft in-block
• OHC: overhead camshaft
  • fewer moving parts
  • less friction
  • more accurate valve timing
• a thrust plate or washer is the method of controlling end play on camshafts

Camshaft follower

• solid type
  • straight body
  • mushroom
  • bottom face of the lifter is slightly convex
  • the lifter centerline is also offset in relation to the cam lobe, thus rotating the follower, and change the wear surface
  • require some valve clearance or lash to allow for expansion.
• roller type
  • the roller is centered on the cam lobe

Engine brake

• electric signal activate the solenoid valve;
• engine oil lift the piston of the oil control valve up to create high pressure oil act on master and slave pistons
• as completing compression stroke, the cylinder injector push rod rises and lift master piston, forcing oil pressure act on slave piston, opening the exhaust valves
• engine brake will only on if following conditions meet
  • dash switch is on
  • clutch is engaged, clutch switch closes
  • transmission in gear
  • engine must be in no-fuel condition
  • cruise control disengaged
• slave valve clearance procedure
• broken hydraulic control valve spring may cause engine brake on even if brake sw is off

Fuel system

• air in the fuel system causes engine run rough and stall
• combustion knock - longer ignition delay period
  • cause by
    • low ambient temp
    • early injection timing
    • low injection pressure
    • fuel quality
  • fix by
    • block heater
    • glow plugs, manifold heaters
    • uel heaters
    • retard timing for starting only
    • raise injection pressure for starting only
• white smoke - unburned fuel
  • cause by
    • lack of heat
    • low injection pressure
    • coolant burned
    • retard injection
• black smoke - incomplete combustion or not enough oxygen
  • lack of air
    • clogged air filter
    • defective turbo
    • leaking in intake components
  • too much fuel (leaking dosing valve), nozzle dribble
• blue smoke - oil is burned
  • worn piston rings
  • excessive crankcase pressure increase pressure on the turbo oil sealing ring
  • leaking turbo: shaft sealing rings are defective
    • oil leaks to turbine or compressor housing
• primary filter

  • = 25 microns

  • first filter after tank
  • combined with water separator
  • subject to vacuum
• secondary filter

  • = 5 microns

  • on outlet side of transfer pump
  • subject to positive pressure
• final stage filter

  • = 1 micron

  • just before injection pump
• filter service
  • close shut off valve if any
  • drain fuel from filter if any
  • turn filter on until gasket touch the base, then turn 3/4 turn
  • bleed the fuel system
    • use a priming pump until feel resistance on the plunger
    • crack return line on injection pump housing
• filter problems
  • loss power or stall if fuel filter clogged
  • loss power of seal is leak, broken, etc.
  • air in filter reducing volume of fuel injected, delaying injection timing, running rough
• transfer pump, self regulated, pulsating output, driven by cam and spring
  • diaphragm
  • plunger type
• pressure test fuel system
  • vacuum gauge installed on inlet transfer pump (inches of Hg, or mm of Hg) 1” of Hg = 25.4 mm of Hg
    • if the number is higher the specs, the problem can be
      • plugged pickup tub
      • plugged tank vent
      • clogged filter before transfer pump
  • pressure gauge on outlet of transfer pump or after secondary filter (1psi = 6.89 kPa)
    • if pressure is low
      • inlet restriction
      • worn pump
      • plugged filter
      • relief valve stuck in the open position
    • compare pressure before and after secondary filter to check pressure differential
  • flow test or pressure on the return line
    • higher pressure, less flow if return line is restricted
  • crank 30 second, cool for 2 minutes
• aerated fuel
  • submerge the return line watch for bubble while running engine >1000rpm
  • sight glass can be used to check for bubbles
• hot fuel cause loss of power
  • as above 37.8C, every 5.5C increase, engine power decrease by 1%
• transfer pump problem
  • fuel coming from vent hole: diaphragm leaking
  • pressure low, leaking inlet, outlet valves
  • wear of plunger and bore
• relief valve
  • stuck open, broken spring, low spring tension -> low fuel pressure
  • stuck close -> high pressure
  • sticking relief valve -> fluctuating
• injection pump
  • port and helix
    • barrel: intake port and spill port allow high pressure fuel exit at the end of injection
    • plunger: has helix - a groove machined outside of plunger, determine effective stroke
    • advance timing by using intake turbo pressure to moving the fuel control rack which changing the effective stroke
  • opposed plunger
    • use adjustable cam ring
    • charging fuel from governer metering valve
    • displace high pressure fuel to injector when opposed plunger roll on cam lobes
    • advance timing by using transfer pump pressure to move the cam ring
  • install injector pumps
    • set 1st cylinder at TDC of compression
    • set injector pump at 1st cyl TDC of compression
    • find TDC by using marks on housing or drop pin
• injector: nozzle holder, spring, nozzle returning nut, intermediate plate, nozzle assemble (need valve + nozzle body)
  • mutil-holes: used on direct injection engines - 2500~5000psi
  • pencil nozzle body and nozzle valve are a one assembly - 2500~4000psi
  • pintle (1 port): used indirect injection engines - 1400~2500psi
• injector problems
  • dirty fuel damage sealing surface bw needle valve & nozzle body, cause nozzle bribble which creating black smoke and nozzle tip coking
    • sticking needle valve resulting in misfire
  • overheat nozzle can brake down diesel creating nozzle tip coking, altering spray pattern
  • water in fuel cause corrosion, create higher pressure and enlarge injector holes
    • heat expand water particle can blow off tip
• injection pump governor
  • control low (base idle or curb idle) & high speed (no load)
  • allow operator input
  • sense rpm and metering fuel
  • supply enough fuel for startup or under heavy load

Cooling system

• radiator cap
• faulty vacuum valve in the radiator cap cause radiator hose collapse
• radiator top hose is hot, bottom hose is cold (suction side)
• when engine is cold, thermostat is closed, opened when engine is hot

Charging system

• fully charge 12.6V or 25.2V; max 14.8V or 29.6V

Alternator

• stator has output to charge the battery though retifier
  • 3 windings wound
    • star or Y - high voltage output
    • delta - high current output
  • has laminated core, which help reduce Eddy current
  • output circuit - to + side of the battery
• rotor creates magnetic field, rotate and creates current on rotor
  • series of north & south pole has field winding in it
  • field circuit - current send to alternator field windings (rotor) which create magnetic field
    • the stronger the magnetic field, the higher the output voltage
    • field current range from 2A to 10A
• capacitor
  • installed bw output terminal & negative diodes’ ground circuit
  • prevent transient voltage spike
  • reduce radio frequency interference - RFI by smooth out ac voltage fluctation
• rectifier
  • 2 group of diodes + & - or called diode bridge or diode plate
• diode trio is additional diodes used to rectify ac output to dc for voltage regulator
• battery will be undercharged if the alternator sense a false voltage created by unwanted high resistances

Service charging system

• one battery has higher resitance can affected the whole group of battery; thus battery group state of charge and condition must be checked first
• alternator terminals
  • R or STA terminal: 14V ac, or 7V dc
    • use to energize field coil if the residual magnetism has weakened, (monentarily use alternator bat + to energize R terminal)
    • operate a tachometer, or relay
• check battery’s OCV (open circuit voltage)
  • fully charge: 12.6V or 25.2V
  • have a surface charge: 12.8V or 25.6, turn head light 3 minute to remove surface charge
  • under charge: less than 12.6V or 25.2V
    • disconnect battery, use battery charger to charge the batteries
• check alternator regulated voltage
  • all electrical loads turn off
  • set engine speed @ maximum alternator ouput (~5000rpm of the alternator)
  • measure across bat + and gnd - on the alternator
    • right: 13.8V - 14.8 or 27.4V - 29.6V
• check alternator output amp
  • set engine speed @ maximum alternator ouput (~5000rpm of the alternator)
  • carbon pile is placed on positive and negative comming to battery from the starter
  • use carbon pile to draw amp until ammeter show its highest value
  • output amp have to be higher 10% of its rated amperage output
• unit battery over charge
  • faulty regulator
  • loose regulator connections
• shorted stator
  • reduce output current; can not meet its rated amperage output
  • the alternator has whining sound and running hot
• opened stator
  • greatly reduce output current
• shorted diode
  • shorted diode can not block current any ways
  • largely drop in output current (60~70%)
  • the alternator has whining sound and running hot
• opened diode
  • whining sound
  • an open diode reduce output current by 33%
• check stator - resistance test
  • ground - terminals to lamination core - expect not OL
  • continuity - terminal & terminal (for Y only) - expect not OL
• check rotor - resistance test
  • ground test - slip rings & bearing surface of the shaft - expect OL
  • continuity test - slip ring to slip ring - expect not OL
• check voltage regulator
  • use a fast battery charger charge the voltage regulator
  • connect test lamp to voltage regulator
  • lamp should turn on when charger turn on, and voltage is between 13.8V 14.8V
  • lamp should turn off when the voltage is over 14.8V
• only use rosin-based solder flux; acid-based solder flux causes corrosion; thus increasing resistance
• fast charging battery should never go over 15.5V or 31V
• use dielectric grease to prevent corrosion

Cranking system

cranking motor

• stationary: brushes, field coils and pole shoes
• moving: armature assembly
  • armature winding
  • the commutator

cranking circuit diagnosis

• upon cranking, voltage drop of
  • battery is at least 9.6V
  • voltage drop bw crank solenoid on starter should be less than or equal to 0.2V
  • for 500A draw, voltage loss should be around 0.7V (0.5V for all cables, 0.2 for selonoid)
• note:
  • upon simulating motor draw, carbon pile draws 500A on 12V system and 250A on 24V system
  • upon simulating mag sw draw, carbon pile draws 100A on 12V system and 60A on 24V system

Electronically controlled fuel injection systems

EUI - electronic unit injection

• components
  • cartridge valve control fuel flow into and out of injector
  • plunger push down create high pressure fuel
• fuel transfer system
  • around 65psi
  • supply clean cool, de-aerated fuel
• operations
  • camshaft lift rocker arm, pushing the top of injector which pushing plunger, creating enough pressure to lift
  • stages
    • pre-injection
      • sol de-energized
      • poppet valve is opened
      • plunger push fuel return to tank
    • injection
      • sol energized
      • poppet valve is closed
      • nozzle is opened
      • plunger continue to push down, injecting fuel to cylinders
    • spill
      • sol de-energized
      • poppet valve is opened, causing pressure drop, needle close immediately
      • plunger continue to push down, force fuel back to tank
    • fill
      • sol de-energized
      • poppet valve is opened
      • plunger moves upwards, suck fuel in, ready for next cycle
• install new injectors required program new calibration code (e-trim) to ecm (every injectors may have fuel delivery variations because of mass production)

HEUI - hydraulic electronic unit injection

• fuel transfer system
  • around 65psi
  • supply clean cool, de-aerated fuel
• operations
  • don’t use camshaft, thus more responsive
  • pressurized engine oil act on intersifier piston which forcing fuel out of injector at high pressure
  • ecm monitor pressurized engine oil 870psi to 3500psi by IAP valve and sensor
  • stages:
    • pre-injection
      • sol’s de-energized
      • poppet valve’s closed
      • piston and plunger is stationary
      • nozzle’s close
    • pilot injection
      • sol’s energized
      • poppet valve’s opened let actuation pressure in
      • piston move down because of actuation pressure
      • 4500psi to open the nozzle
      • plunger has a groove, connected to the end of the plunger, when groove aligns with the spill port in the barrel, pressure drops, end pilot injection
    • main injection
      • plunger keep move downwards cover spill port, nozzle’s opened again to inject more fuel
    • end of injection
      • sol’s de-energized
      • poppet valve closes, open the drain port on the top of poppet valve, allowing actuation oil pressure to escape
      • piston and plunger move upwards by return spring as actuation pressure’s relief; this unseat the check ball, fuel suck into fuel chamber
      • nozzle closes, as fuel pressure drop
• IAP (injection actuation pressure ) valves determines pressure by using sensor inputs
  • throttle position - TPS
  • engine speed - VSS
  • manifold pressure - TBS
  • coolant temp - CTS
  • low actuation pressure is for low engine speed and light load
  • high actuation pressure is for higher engine speeds and loads

Common rail fuel injection system

• components
  • common fuel rail (accumulator)
  • pressure limiting valve (relief valve), mounted at the end of the rail
  • rail pressure control valve (similar IAP valve)
  • rail pressure sensor
  • flow limiting valves, used to prevent overfuelling of a cylinder in the event of an injector stuck in open position
    • it will shut off fuel flow to injector when it exceeds 1.5 times of the normal flow
  • injectors
    • needle valve is held by spring and fuel pressure on the top of intermediate valve
    • energize sol, bleed high pressure fuel off the top of the intermediate valve, which allow fuel pressure in the nozzle overcome spring pressure and inject
• fuel transfer system
  • around 80psi - 130psi
  • supply clean cool, de-aerated fuel

Electronic unit pump (EUP) Mack, Mercedes

• components
  • electronic unit pump, camshaft actuated,
• fuel transfer system
  • around 70psi
  • supply clean cool, de-aerated fuel
• stages:
  • fill
  • pre-injection
  • injection
  • spill
• install new injectors required program new calibration code (e-trim) to ecm (every injectors may have fuel delivery variations because of mass production)

Service fuel system

• before taking injectors out do:
  • disconnect battery cable
  • drain the fuel
    • use compress air at a regulated 65psi blowing to inlet fuel passage in cylinder head
    • this is important, fuel trap in cylinder head can cause hydraulic lock, damage cylinder rod

Air induction system and turbocharger

• intercooler, aftercooler, or air cooler is used to cool the air after it has been compressed by turbo
  • maximum engine performance occurse when the air is cool, less than 33C
  • hot air is less dense will cause power loss.
• intake manifold pressure test
• plugged drain line on turbo charge can cause turbo charger bearing failure
• volumetric efficientcy (VE) = volume of air taken in / actual cylinder volume
  • engine speed increase, VE decreases
• naturally aspirated has a volumetric efficiency of 75%~85%
  • engine cylinder would only receive about 75-85% of the air that is actually required to completely fill the cylinder
• turbocharged engine has following feature compared to naturally asperated engine
  • compression ratio is lower
  • valve overlap will be increased
  • retard injetion timing
  • fuel pump output and/or fuel injector sizes are increased
• turbocharger components:
  • turbine: housing, turbine wheel, wastegate or impeller
    • mount om exhaust side
    • turbine housing can have a separate port that is used to divert some exhaust gases away
    • wastegate controls the opening of this port
  • compressor: housing and compressor wheel
    • mount on intake side
    • a nut is used to retained the compressor wheel on the turbine shaft
    • diffuser plate or nozzle vanes smoothly direct the boost air into the intake manifold
  • 2 small piston style sealing rings help prevent
    • oil from entering the housings
    • exhaust gases and compressed air from entering oil cavity
  • large O-ring or RTV (room temperature vulcanizing) sealant is used bw compressor housing and center housing
  • metal-to-metal seal is used bw turbine housing and center housing

Dust ejection system

• dust cup and dust ejection valve: use a one way rubber ejector valve, swirling air
• exhaust gas aspirator: use scavenging effect of the exhaust gas to draw dust particles from the dust bowl into the exhaust system

Air filters

• oil bath type air filters - 98.5% effective
  • work best when the air flow is high; the low airflow speed, the less effective oil filter work
  • particles are collected in the oil bath at the bottom of the air cleaner
  • high oil level can cause engine runing rich and overspeed
  • hilly terrain can effect oil level; thus oil can be drawn to engine
• dry type air filters - 99.5 effective
  • work at all engine speeds
  • single stage filter use a pre-cleaner
    • pre-cleaner cleans larger particles
  • double stage filter
    • inner element is the secondary or safety filter which protects engine if the primary filter develops holes
  • pleated paper is used to provide a large surface area for the filter
• air intake hose should use constant tension hose clamp as those hoses expand and contract during operation
• air filter service interval is established by on the basis of vehicles’ operating condition or air restrictor gauge
  • filter is clean; restrictor gauge should show 8-12 inches of water
  • filter is dirty; restrictor gauge should show 20-25 inches of water
• place a trouble light in the center of the round filter. Bright points of the light indicate signs of air leakage or dirt entry can occur
• blowing 30-50psi air @ 90 degree to the pleats though the air filter in the opposite direction of normal airflow

Service air intake system and turbocharger

• do not use a mercury manometer (use water manometer); mercury can be drawn to the intake system which can produce poisonous gas
• load the engine to maximum horsepower to test turbo boost pressure

• lack of power and low boost pressure in turbocharged engines
  • leaking or restricted intercooler
  • worn engine parts as pistons, rings or liners
  • faulty fuel injection system, pump or injectors
• excessive noise
  • carbon build up causes turbo out of balanced; rubbing action bw turbo wheel and housing occur
  • lubrication problems
    • plugged oi supply and oil passage can starve turbo bearing, causing bind turbine shaft
    • plugged oil return, or oil return line is too small; oil can build up in center housing, thus increasing pressure on sealing rings
    • shutdown engine too quickly, the oil burns and cokes on the bearing shaft, cause premature wear on the bearing
  • air and exhaust leaks can cause noise
• leaking turbo
  • internal: blue smoke, oil leakage is evident on the compressor, turbine wheels, increase carbon build up
  • external: defective oil inlet or oil drain gasket
• exessive shaft end play
  • the thrust washer and related components wear, the axial end play will increase
  • too much endplay wheels can rub on housings, creating noise and drag
  • use dial indicator to check
• excessive radial play
  • use feeler gauge check side clearance of the wheels and the housings
  • adjustment is not possible, replace the turbo
• turbo removal
  • disconnect wastegate valve before removing turbo
  • mark the compressor and turbine housing in relation to the centre housing
  • check id plate for ordering parts
  • turbine housing can be immerse in hot tank
  • compressor housing made by aluminum, use clean Varsol
• turbo installation
  • use antiseie to secure turbor charger to the exhaust manifold
  • pre-lube the turbo bearing while rotating the compressor wheel by hand
• shutdown time: idle engines 3-5 minutes before shutting it down, allow oil to remove heat from the turbo

Aftercooler/intercooler

• air-to-air intercooler or air-to-air aftercooler (ATAAC)
  • best in mobile equipment with steady flow of outside air
• air-to-coolant aftercooler
  • stationary application or off-road equipment which does not have a constant air flow
  • pressurized turbocharged air is forced through tubes that are surrounded by moving engine coolant

Service aftercooler/intercooler

• air-to-air aftercooler
  • cap intlet and outlet port the the test plugs. One of the test plug has a gauge and air quick connect
  • pressurize ATAAC with compressed air according to specs. the intercooler must maintain the pressure for a specific time interval
  • air coolers need to be cleaned on a regular basis
• air-to-coolant intercooler
  • remove and drain coolant from the aftercooler
  • plug all ports and submerged it to warm (82C) water tank
  • pressurize the aftercooler ~40psi, look for air bubbles
  • leaks can causes
    • compressed air to coolant
    • coolant may enter the intake, cause white smoke, and loss of coolant

Variable displacement turbohargers (VDT) and Wastegates

Wastegate

• wastegate is a valve that senses turbo boost pressure and open a port to bypass exhaust gases around the turbine wheel which controls the speed of the turbine
• the wastegate valve stucks open, will cause low power as boost pressure will below the specs
• the wastegate valve stucks close, turbo speed will be unregulated which can cause engine and turbo damage

VDT

• use in conjunction with EGR to control
  • turbo speed
  • boost
  • exhaust backpressure
  • help improve engine brake
• sliding nozzle vane
  • control exhaust gases flow to the turbine by sliding the nozzle vanes back and forth
• pivoting nozzle vane
  • control exhaust gases flow to the turbine by turning the pivoting vanes close and open

Exhaust system

• when an exhaust manifold is routed past a cab or sleeper compartment the exhaust components must be secure, leak free, quiet, and no vibration
• flex tubing is used when movement bw major components occur; wide-band clamp is used to connect bw rigid pipe and flex pipe
• rain cap has a counterweight that will cause the cover to fall to close position when engine is not running
• spark arrestor is used to prevent spark flying out of the exhaust
• do not drill holes in the frame or weld brackets on the frame
  • holes may lead to the creation of cracks in the frame
  • the frame rails are heat-treated and welding could cause the frame rail to be weakend
• dust and dirt in the air often has a high sand content, upon heated during the combustion process, abrasive glass like particles are created which causes extensive wear on the cylinder liners
• upon checking for exhaust leak, look for black soot trails around various gasket surface areas
• if exhaust outlets are restricted, it will create more pressure on various gaskets and clamps.

EGR - exhaust gas recirculation

• Introduce EGR into combustion chamber reduce NOx, but:
  • increasing CO and HC emissions
  • loss of power
  • reduced fuel economy
• EGR valve: butterfly or poppet, allow exhaust gases go back into combustion charmber
• EGR actuatior
  • air
  • electrical (PWM on motor)
• EGR cooler
  • air density decrease when it’s hot, EGR cooler bring hot air down to 200C
  • cool by coolant, which require high-cap water pump
• ECM uses a differential pressure sensor to determine how much the EGR valve needs to open
  • 2 ports: 1 install at the inlet, one at the restriction (venturi)
• EGR temperature sensor is located in the delivery pipe before the mixer
• VDT variable displacement turbocharger or VGT variable geometry turbocharger
  • has vanes which can be closed to increase exhaust backpressure, which push more gas through EGR valve
• ECM control VDT under 3 modes:
  • EGR mode:
    • EGR valve opens
    • adjusting position of vanes can increase exhaust backpressure and EGR flow
  • Brake mode:
    • EGR valve close
    • VDT’s vanes is closed, which increase turbo boost, resulting in effective engine brake as more energy is need to push the piston up on the compression stroke
  • Boost mode (engine acceleration)
    • EGR valve close
    • ECM adjust vanes to provide correct boost

After treatment

• combustion produce: CO, NOx, particulate matter, SOx
• DOC - diesel oxidation catalyst - reduce HC and CO emission
  • mounted as close as possible to engine to take advantage of the heat for catalyst
  • contains ceramic core coated with platinum or palladium as catalyst (help reaction happen at lower temperature)
  • core has diamond-shaped cell, arrange as honeycomb
  • CH + O2 = H20 + CO2; CO + 02 = CO2
• PDF is a regeneration soot (carbon) collector - reduce NOx and C
  • reduce soot
  • can be a simple filter, but it will clog fast not good for continuous operation
  • DPF can regenerate (self-clean) so extend service interval
  • core has diamond-shaped cell, arrange as honeycomb
  • NO2 + C (soot) = CO2 + NO
• regeneration
  • passive: exhaust temp > 500F, automatic
  • active: control by a switch, require vehicle park, cooling fan will be on, engine rpm increase
    • diesel is injected into exhaust downstream of turbo, diesel will be react with catalyst in DOC, thus increase temp ~ 1100F
    • inject by
      • dosing valve
      • pulsing engine’s fuel injectors on exhaust stroke (common rails)
  • ECM monitor by
    • 3 temperature sensor (plus before DOC)
      • control regen duration
      • warning light for high exhaust system temperature (HEST) on 450C & travel at 8 km/h
    • 2 pressure sensors (before and after DPF)
      • pressure drop increase will initiate regen and provide warning signal
• DPF cleaning
  • hazardous
  • DPF core is direction, so mark before removing
  • after cleaning, it has to be test for an accepted flow rate
  • thermal cleaning can be used as last attempt to restore DPF
• EGR system: use with DOC, DPF
• NO EGR system: DOC, DPF, SCR (selective catalyst reduction)
• SCR - selective catalyst reduction - use to reduce NOx just like EGR, but not lose power
  • located down stream of DOC & DPF
  • DEF is injected into decomposition chamber (mixing pipe)
  • SCR = SCR cat + AMOX cat
    • SCR convert NOx to nitrogen and water NO + NO2 + 2NH3 = 3H20 + 2N2
    • AMOX has platinum coating, braking up any ammonia that slips through SCR cat
  • Temperature sensor, NOx sensor at outlet and in let
  • components:
    • dosing metering unit: send a metered unit of def to injector
      • air inlet
      • air pressure sensor
      • def heater
      • def temp sensor
      • def pressure sensor
    • DEF injector
    • dosing control unit

Clutch

• types:
  • push-type medium duty
  • pull-type heavy duty
• actuation
  • mechanical
  • hydraulic
  • air over hydraulic
• flywheel:
  • provide smooth friction surface for one side of clutch disc to work on during engagement process
  • pilot bearing is used to pilot the transmission input shaft which helps to center the clutch disc in relation to the pressure plate
  • types
    • flat
    • countersunk
      • allow to use 2 clutch discs; increasing friction area, thus increasing the torque load
• clutch cover
  • contain and drive the pressure plate
  • bolted to fly wheel, always rotate with it
  • cast iron: absorb more heat, rigid structure
  • stamped steel: lightweight, allow higher engine speed
• pressure plate
  • located in & driven by clutch cover
  • one friction side is smooth
  • made by cast iron
• pressure springs
  • perpendicular coil springs
  • angled coil springs
  • diaphram spring
• clutch discs
  • rigid
    • used in applications where a limited amount of engagement and disengagement occurs
  • dampened
    • wave springs help reduce impact loads (torsional shock load) during engagement
• linings
  • organic or non-asbestos organic (NAO)
  • ceramic - heavy duty applications, long service life
• intermediate plate
  • can not fastened tightly to flywheel or clutch cover
  • flywheel drives intermediate plate through drive pins or
  • drive by drive straps bw clutch cover and intermediate plate
  • have anti-rattle springs help reduce vibration and noise
• clutch release lever
  • compress the pressure springs, thus moving the pressure plate closer to the clutch cover during the disengagement process
• release bearing assembly
  • move clutch release levers
  • push type
    • only rotate during the engagement and disengagement process
  • pull type
    • always rotate upon engine running, but operate under load during the engagement and disengagement process
    • pulls release bearing, sleeve, and levers away from pressure plate
• clutch adjustment
  • manual
    • adjust threaded push rod that moves the release bearing yoke shaft
    • 1/8” between yoke and release bearing; 1/2” between release bearing and clutch brake
  • self adjustment
    • self adjusting every time when disengage and engage
    • there is limit to avoid adjusting clutch too tight which could lead to premature wear
• clutch brake
  • use to stop rotation of clutch disc and input transmission shaft upon moving from N to 1 or N to R
  • help prevent gear clash
  • DO NOT floor the clutch while driving, this burn clutch brake! (specially the solid clutches)
  • torque-limiting clutch will slip above a certain pre-determined torque load
• service
  • slipping:
    • do not move vehicle at high gear, causing clutch slip, creating lost of heat, weakening pressure spring
  • dragging
    • difficult to shift caused by clutch partially disengaged, gear clashing may occur
  • freeplay is the amount of movement of the clutch pedal before resistance is encountered (1”)
    • too little: increase wear of friction surface, release bearing and levers are in constant contact
    • too much: decrease the amount of remaining pedal movement available to disengage the clutch
      • can cause failure to completely disengage the clutch, thus clutch dragging
  • chattering
    • worn engine mounts, loose drivetrain comps
    • worn clutch disc splines, trannny input shaft splines and warped friction disc surface
  • a vehicle is difficult to get out of gear, clutch disc may be wrap
  • vibration
    • imbalance clutch assembly
      • linings separated
      • debris trap in clutch assembly
  • excessive drive pin clearance can cause a double clutch disc to rattle when clutch is released
  • remove clutch assembly
    • replace 2 clutch assembly mounting bolt with long guide studs, help to slide it out easy
    • clutch disc aligning tool is used to help control the clutch disc
    • check warpage with straight edge and a feeler gauge on flywheel, intermediate plate, pressure plate
  • measurement on engine flywheel housing
    • crankshaft end play check
    • flywheel face runout
      • out of spec will cause uneven contact with friction surface
    • flywheel bore runout
      • pilot bearing located in this bore
  • clutch adjustment
    • clutch free play reduces if not adjusting the clutch regular
    • lock plate need to remove prior to adjusting the clutch
    • adjust the clutch to spec gap bw yoke and release bearing (1/8”)

Driveline

• A trunnion is a highly polished bearing surface, is located at the end of each universal joint cross arm
• Misalignment of the axle housings force the u-joints to operate at greater angles, thus vibration increase
• Inspection of u-joint trunnion wear
  • spalling: over load
  • end galling: lack of lube, incorrect working angle
  • false brinelling: lack of lube, operate at zero angle
  • pitting: contamination
• troubleshooting vibration
  • stationary test
    • separated engine, clutch or torque converter vibration with drive train problems
  • road test
    • low speed vibration is most likely wheel, tire, wheel bearing which rotates at 1/4 speed of driveshaft
    • high pitched sound & vibration, specially during increase and decrease in speed, indicating driveshaft problems
  • checking driveshaft
    • not missing any weights
    • no dents
    • properly phased
    • runout
    • worn u-joints
    • axles alignment

Transmission

Manual

• low level oil cause bearing and gear failure due to lack of lube
• high level oi cause oil foaming, air bubble reduce the lubrication qualities, causing bearing and gear failure
• HLA: hydraulic launch assist: provide assist to propel the vehicle from a stop to assist acceleration @ low speed
• mechanical air shift 18 speed
  • start with LO gear, low range, low splitter
  • go high split (forward), immediately press clutch & ease gas
  • go low split (backward), press clutch, go neutral, then reduce RPM (~300), and upshift to 1st gear
• range shift activates from slave valve, then range cylinder
  • interlock prevent range shift happened if transmission is already in gear
  • push transmission back to neutral will engage range shift
• splitter shift activates splitter cylinder directly
• shift-by-wire
  • inertia brake mounted PTO opening, used to slow down input shaft and counter shaft speed, allowing to shift happen faster
• gear inspection, replaced if any of following:
  • spalling: overloaded, destructive pitting with larger diameter craters and shallower in depth;
  • scoring/galling:
    • insufficient oil film bw mating gear teeth caused by incorrect type, grade, and level of oil
    • high operating temperature
  • burned:
    • blue from teeth area inwards: excessive torque combined with insufficient lube bw geer teeth
    • blue from middle of mainshaft gear outwards indicates mainshaft installed with insufficient clearance
    • blue from inside of mainshaft gear outwards indicate mainshaft lack of lub because of incorrect towing, coast on neutral
  • impact fractures:
    • shock load, foreign object
    • have crystalline finish
  • fatigue fractures:
    • extreme high stress on a gear tooth over a period of time
    • have beach marks
  • stringers/gas pockets
    • are weak points in the gear
    • difference in fracture shape
• synchronizer assembly has following main components
  • shift sleeve or slider which is shifted by a shift fork
  • blocking ring, blocker ring, baulk ring
  • synchronizer hub or hub which is attached to output shaft
  • keys, balls, struts, and the spring depending on the design
    • this mechanism keep some pressure against the outer slider, thus retaining the hub in the slider
  • constant mesh gear or speed gear which is constantly rotating with input shaft, and countershaft

Automatic

Input shaft

• transmission input shaft or clutch shaft receives engine power from trapped clutch dics, and transfer to transmission input shaft gear (or transmission drive gear or main drive gear)
• tapered roller bearing is located in the casting head of the input shaft gear
  • center the input shaft
  • provide a means of adjusting mainshaft end play
  • use shim to preload the bearing to specs

Mainshaft

Countershaft

Transfer case

• front axle declutch is a mechanism to disengage the torque to the front drive axle
• range shifting
  • transfer case acts as a aux transmission
  • can engage: a direct drive, neutral, and a low range gear set
• proportional differential and lockout
  • the main driveshaft is splined to the carrier
  • output to rear axle is splined to ring gear 70% torque
  • output to front axle is splined to sun gear 30% toruqe
  • a lockout clutch is used to locks front output shaft (sun) to main driveshaft (carrier), thus 100% torque go to rear axle
• Power takeoff
  • are susceptible to overspeeding if the transmission is placed in the wrong gear
• breather
  • use to relieve pressure built up from heat generated in the transfer case housing
  • air leak in shift cylinder can cause excessive pressure

Auxiliary drive

• drive whenever engine is running
  • a hydraulic pump driven from the front of crankshaft
  • rear engine-mounted drive requires a special flywheel housing
• transfer case power takeoff
  • large torque
  • main transmission have to be in gear
• dropbox
  • send power straight through upon driving
  • power to rear is interrupted upon using accessory
• power tower
  • mounted on top of aux transmission
  • receive torque from countershaft
• power takeoff
  • mounted to the main transmission, aux transmission or transfer case housing
  • 6 bolts & 8 bolts size
• PTO actuation
  • cable: push-pull type of activation system
  • mechanical: linkage, same as transmission shift linkage system
  • air: valve or solenoid
  • electric: solenoid
• additional amount of lubricant is required for aux drive
• gear backlash is crucial
  • 0.006 or 0.012” backlash
  • use shim on PTO gaskets: 0.010” and 0.020” shim
  • use a special filler block when the maximum amount of gaskets used
  • to measure:
    • the shift cover or inspection cover is removed
    • dial indicator is install
    • rock PTO gear side to side as holding transmission gear stationary
  • insufficient backlash makes whining noise
  • excessive backlash makes clattering noise
• adapter plate:
  • use to mount hydraulic pump directly to the plate
  • reduce force act on transmission case upon mount the pump
• adapter housing
  • change the angle of mounting component, to clear obstruction

Drive axle assembly

• GAWR: gross axle weight rating
  • the amount of weight that the axle can safely carry
• GVWR: gross vehicle weight rating
  • the total weight of the vehicle and its load
  • do NOT overload GAWR even if GVWR not yet have been reach
• GCWR: gross combination weight rating
  • combined weight of the tractor, the trailers and their loads
• if more traction is required, the extra axles added must be driving axles
• drive axles gear ratios
  • tooth combination: 39-6
    • drive pinion: 6 teeth
    • driven bevel gear: 39 teeth
    • gear ratio: 39/6=6.50 which means 6.50:1
  • choose differential ratios consider 2 things:
    • startability: too high ratio 2:1 will make it hard to start a heavy load
    • fuel economy: too low ratio 9:1 will effect more on fuel economy
• when drive axle operates at an angle of over 12, a standpipe should be used
• gaskets are NOT used bw housing, it uses RTV sealant
• check end play of both input and output shaft
  • can cause vibration of it is out of specs
• perform plug swap, inspecting the contamination on the plug
• lose suspension components can cause noise
• mismatch tires cause excessive heat and wear due to continuous diff action
• noise on drive
  • loose, worn bearings
  • low/wrong lubrication level
  • excessive backlash, end play
• noise on coast
  • pinion and ring gear too tight
• intermittent noise
  • warped ring gear
  • loose diff case bolts
• constant noise
  • flat spot on bearing, gears
  • bent axle shaft
  • worn pinion splines
• lub
  • oil temp should not exceed 250F or 121C
  • after fill drive axle assembly with correct amount of lub, drive the truck for few minutes, then shutdown 5 minutes to recheck the oil level, top up if needed
  • low oil level causes overheat, losing oil film quality
  • high oil level causes foaming, reducing oil film quality
  • if oil is contaminated, wheel end assemblies must be removed, the hubs cleaned, and bearing inspected
• pre-disassemble check: backlash in case the axle has to be reused
  • measure at 4 evenly positions on the ring gear
• assembly differential
  1. pinion bearing preload: apply press load while checking rotation torque of pinion
     • use norminal bearing spacer for initial check
  2. tooth contact pattern (adjust pattern can affect backlash, thus, doing the pattern before backlash)
     • use a pry bar to apply load to ring gear on checking pattern
     • move ring affects heel and toe
       • excessive heel: lower pattern, move ring towards pinion
       • excessive toe: moving away from pinion
     • move pinion affect: face and flank (need to readjust backlash)
       • excessive face: move pinion in
       • excessive flank: move pinion out
  3. side bearing preload (backlash)
     • adjusting rings used to adjust bearing preload
     • adjust until end play is eliminated, but backlash bw the pinion and ring gear still exists
     • move ring gear close to pinion, decrease backlash
     • move ring gear further from pinion, increase backlash
  4. pinion depth
     • nominal dimension is measured from the end of the pinion to the bevel gear center line
     • positive (+) etch number indicates how much further the pinion need to move away from the center line
     • negative (-) etch number indicates how much closer the pinion need to move close to the center line
     • to position pinion in relation to the center line of the bevel gear
       • shim between bearing cage and the differential carrier
       • or shim between the inner pinion bearing and the pinion gear
  5. bevel gear run out
  6. thrust screw
     • mark the spot with the most back face runout toward the thrust screw side of the bevel gear
     • thread the thrust screw into the diff carrier until it seats in the thrust block
     • back off 180 degree
     • rotate, make sure that thrust screw does not bind at any location
• assemble inter-axle differential
  • input shaft end play
    • established with shim bw bearing cage and the housing
  • apply 60 psi air pressure to shift cylinder, then tighten the adjusting screw one turn after the screw touches the end of the shaft
• when selecting particular gear oil, expected working ambient temp must be consider
• wheel lock must be engaged to remove the carrier assembly from the housing
  • a special bolt threaded into the air fitting port OR
  • apply 80-120psi shop air to the shift cylinder

Drive axles components

open differential

• drive axle housing (banjo housing), stamped steel
  • mounting place for brakes, suspension components
  • has spindle surface where the wheel ends are installed
  • weight of vehicle is transfer from the suspension through the axle housing to the wheel hubs, rims, and tires
• carrier housing
  • made by cast iron
  • can be integral carrier which is a part of the housing (light weight application)
  • hold internal gear components
  • have 2 removed bearing caps at the rear that use to secure differential case bearing and adjusters
• pinion cage or pinion bearing houses the bearing that support the pinions
• pinion is supported by 2 tapered roller bearings which is put under preload to keep the pinion located properly
• overhung mount pinion
  • flat surface at the end of the pinion gear
• straddle mount pinion
  • a short tub shaft that extends past the end of the pinion gear
  • roller bearings on the tub shaft helps the pinion gear from deflecting away from the bevel gear under heavy loads
• amboid - top mount
• hypoid - bottom mount
• thrust screw & jam nut
  • located opposite the pinion gear
  • prevent the bevel gear from deflecting away the pinion under heavy loads
• differential case
  • consist of two halves bolted together
    • a flanged half is bolted with bevel gear
    • a plain half has recess housing cross shaft
  • supported by 2 tapered bearing
• differential pinion gears or spider gears
  • mounted to each leg of the cross shaft
  • free spin around cross shaft
• side gears
  • mounted on each case half
  • mesh with spider gears
  • can rotate at different speed than the case
  • has internal splined to axle shafts
• path of power
  • drive pinion
  • bevel gear
  • diff case
  • cross shaft
  • spider gears
  • side gears
  • drive axle shafts
• differential lock
  • air pressure applied moves shift fork
  • a shift collar or sliding dog clutch lock one side axle gear to differential case
• planetary two speed differential
  • input: bevel gear and planetary ring gear which are one piece
  • output: planetary carrier and differential case which are one piece
  • low speed: sliding sun gear inward, meshed with low speed clutch plate (bearing adjuster, a part of diff housing), thus holding sun gear
  • high speed: sliding sun gear outward, internal splines of the sun gear are locked to planetary carrier (high speed clutch plate), thus locking 2 members of planetary gear set

inter-axle

• allow different speed between front drive axle and rear drive axle
• components
  • helical drive gear
    • one side is a side gear which meshed with pinion gears
    • one side is dog teeth gear which meshed with input shaft lockout shift collar
  • input shaft
    • first set of splines: splines to input yoke
    • second set of splines: splines to lockout shift collar, which will splines to helical drive gear upon locking front and rear axle together
    • third set of splines: splines to cross shaft which driving the side gear of helical drive gear and output shaft side gear
  • inter-axle differential case
    • receive torque from input shaft through internal spline of the cross shaft
    • then drive differential pinion gears
    • then drive side axle of helical drive gear and output shaft side gear
• path of power
  • input shaft
  • inter-axle differential cross shaft
  • inter-axle different pinion gears
  • helical drive gear and output shaft side gear
    • from helical drive gear to helical driven gear, then front axle drive pinion
    • from output shaft side gears to output shaft

axle configuration

• semi-floating:
  • can NOT remove axle shaft without support vehicle
  • the weight of the vehicle and cargo is transmitted through the axle housing, bearing, and axle shaft
• full-floating:
  • can remove the axle shaft without support vehicle
  • the weight of the vehicle and cargo is transmitted through the drive axle housing

outboard planetary drive

• input : axle shaft splines to sun gear
• ring gear is stationary
• output: planetary carrier bolted to the hub assembly

driving steer axle

• 3 pieces designs: inner shaft, outer shaft (ball shaft), and a cage ring assembly
• axle housing has a axle ball and a ball socket

no-spin differential

• normally locked or engaged & drive both wheel at the same speed
• unlock during cornering, allow outer wheel to run faster than inner wheel
• no cross shaft
• ratcheting noise will occur during the cornering process

service

• standpipe should be installed if
  • the drive axle assembly is installed of over 12
  • operated on steep grades for extended periods
• end play of input and output shaft
  • if it’s out of spec, it can show sign of internal wear, which can cause vibration
• mismatch tires causes excessive heat and wear due to continuous differential action
• perform a plug swap to inspect contamination on the plug
• noise on coast: pinion and ring gear too tight
• intermittent noise: warped ring gear, loose differential case bolts
• overheating: normal 71C - 104C; >121C oil lose their quality
• pre-disassembly check
  • pinion to bevel gear backlash
  • mark bearing side caps

Electrical and Electronic system

Battery

• RC: reverse capacity is the number of minute a battery can delivery 25A @ 27C and maintain cell voltage above 1.75V
• AH: ampere hour is the number of amperes a battery can delivery @ 27C for 20 hours and maintain cell voltage above 1.7V
• CCA: cold cranking ampere is the number of amperes a battery can delivery @ -18C for 30s and maintain cell voltage above 1.2V
• CA: cranking ampere is the number of amperes a battery can delievery @ 0C for 30s and maintain cell voltage above 1.2V
• specific gravity is the measurement of the density of a fluid or solid compared to that of water
  • fully charge battery has a specific gravity of 1.265 - 1.280 @ 27C
  • specific gravity of water is 1.000
• battery with a built-in hydrometer or ball and tube hydrometer
  • the sight class is clear: replace the battery, do NOT testing, charge or boosting
  • the sight class has a green dot: above 75% charged (greater 1.225), specific gravity is around 1.225 or higher
  • the sight class is black: below 75% charge (less than 1.225)
• battery load test
  • remove surface charge by drawing 300A for 15s; then turn carbon pile off wait 15s cool down
  • draw half of CCA or 3 times of AH for 15s
  • check final voltage must be greater than 9.6V
• do not boost battery if suspect frozen battery or has low electrolyte
• boosting connection
  • • discharged battery
  • • booster battery
  • • booster battery
  • engine ground of discharge battery 18” from the discharge battery
• parallel connected battery
  • CCA & RC is multiplied
• series connected battery
  • voltage is increased by the voltage of each battery in the group
• slow charge is the best method of charging, allow battery charge to 100%
  • charge 1% of CCA or 7% of AH

sensors

• Thermistors
  • PTC: positive temp coefficient, temp increase, resistance increase
  • NTC: negative temp coefficient, temp increase, resistance decrease
  • wired in service with ECM: 1 lead is 5V ref, other is ground
• Pressure sensor
  • 3 wire: 1 ref, 1 ground, bridge voltage wire to ecm
• TPS: potentionmeter
  • 3 wire, 1 ref, 1 ground, signal wire to ecm

SAE fault code

• CAN 2.0 (Control Area Network) SAE J1939 250 kbps
• MID message indentifier - the component - tells which system it is coming from, e.i engine 128, ABS 136, etc.
• SID system id - the sub system affected, (Injector 6, TPS, pressure sensor, etc.) - 3 digits
• PID parameter id - type of data in term of reading - engine oil pressure, coolant temp, etc. - 3 digits
• FMI failure mode id - type of failure - too much voltage, not enough voltage - 2 digits
• pressure sensor - high voltage
  • ref wire can be shorted to signal wire back to ecm, thus high voltage code
• temp sensor - low voltage
  • ref wire can be shorted to ground, thus 0V is seen bw ref and ground wire
• temp sensor - high voltage
  • ref wire to the sensor is broken, thus 5V is seen bw ref and ground wire
• Data link connectors:
  • 6 pin : J1587, J1708
  • 9 pin: J1939
  • key switch to be OFF when connecting data link port

CAN (Controller Area Network) bus J1939

• CAN use a bus topology
• at two far end of the main bus (backbone) needs terminating resistors - 120ohm
  • usually a deutsh termination plug which has a builtin 120ohm resister, encapsulated in epoxy to keep it watertight
  • terminating resistors use to terminated the signal preventing it reflecting back which can interfere with the next data signal
• along the backbone, there are different devices stubbed (branched) out
• when there is no data being broad cast: voltage between high-ground and low-ground are ~2.5V
• CAN low : green 2.5V - 1.5V
• CAN high : yellow 2.5 - 3.5V
• shield J1939-11 cable has non-insulated drain wire connected to battery ground
  • drain wire prevent internal signals from radiating out and,
  • block outside electromagnetic inference from corrupting the signal

troubleshooting CAN bus system

1. verify termination resistors
   • resistance between hi and lo on a node should be around 60ohm which is parallel combination of two 120ohm terminating resistors
   • if it shows 40ohm, the bus can have 3 terminating resistors which is not desirable
   • if it shows 120ohm, it is missing a termination resistor
   • to figure out which side of the harness missing, disconnect the backbone before the testing node
     • measure resistance between hi & lo on the suspected node
       • if it show more than 120ohm, usually will show kohm, then problem on this side of the backbone
       • if it show 120ohm, then this side of the backbone has a terminating resistor
   • notes: some end node can have a built-in terminating resistor that is software seletable
     • this means that it will show no resistance if the bus is not power
2. hi & lo connect backward
   • voltage between hi & ground is always greater than voltage between lo & ground (or hi voltage > lo voltage in short)
   • if it is shown the opposite, there is at least one hi & lo was wired backward a connection point
   • unplug each node, and verify for voltage of hi & lo, until it shown a hi voltage is greater than a lo voltage
3. CAN signal missing (opened wire)
   • tested each node for hi and lo voltage
   • if one CAN signal has ~0 voltage, there is an open
4. CAN signal shorted to ground
   • whether hi or lo shorted to ground, it is shown low voltage reading on both hi & lo as hi and lo signal are connected by termination resistors
   • disconnecting termination resistors at both far end of the backbone will help to located whether it is hi or lo signal is shorted to ground
   • disconnect all devices, then connect one at the time while verifying hi or lo voltage
     • if one node is connected, hi or lo voltage change to less than 2.5V, that branch has the short
     • now, check resistance between ‘hi & ground’ and ‘lo & ground’ on the node
       • internal resistance between hi and lo on the node usually is high in kohm range

four point testing procedure

• live side: voltage is measured from the source positive to load positive

SRS supplemental restraint system

• a shorting bar shorts across both terminals at an air bag connect upon unplugged to prevent accidental deployment of the air bag
• it provides a low resistance path to the other terminal back to ground
• if the air bag has been deployed, the clockspring assembly need to be checked and replace if needed
• straightening the wheels & taping the top cover to the bottom housing before removing the clockspring
• to center the clockspring
  • turn counter-clockwise until snug
  • turn clock-wise 4.5 turns
  • align the arrows on the top cover and the bottom housing
  • tape the top cover with the bottom housing

Steering system

• input shaft -> intergal steering gear -> sector shaft -> pitman arm -> drag link -> upper steering arm -> lower steering arm -> tie rod
• drag link
  • threaded ends must be completely inserted into drag link lube
  • air hammer with flat punch strikes on pitman arm while prying drag link away from the joint
• king pin, bushings, and thrust bearing
  • king pin horizontal movement while rocking the top of tire in and out
    • replace bushing if it shows more than 0.015” play
  • king pin vertical movement while prying knuckle downward
    • replace shims and thrust bearings if it shows more than 0.012” play
• grease seals should be installed that the lip is pointing toward center of the knuckle
• tie rod end play
  • axial (up and down)
  • radial (side by side)
  • it should be less than 0.060”
  • need to reset toe
• flushing steering gear
  • empty the reservoir, disconnect steering gear hoses, and turn steering full left and full right
• filling the steering system
  • fill reservoir nearly full. Do not steer. Start engine 10s, check and refill. Repeat 3 times
  • No not steer, check & refill with engine run 2 minutes
  • auto bleeding
    • steering full left and right several times while engine is running
  • manual bleeding
    • steering full left and right several times while engine is idling
    • stop at the straight ahead position to loosen the bleed screw
• hydraulic test
  • preparation
    • install pressure gauge, flowmeter, and load valve between pump output and steering gear
    • put engine in idle
    • close load valve (less than 5 seconds)
    • bring hydraulic oil to operating temperature 66C-71C
  • performance testing
    • close the load valve, check pump pressure, should be 1900psi - 2275psi
      • higher: replace relief valve
      • lower: check relief valve first, then look at replacing or rebuilding pump
    • check flow rate at idle/1500rpm upon closing the load valve and releasing it
      • compare to minimum & maximum flow rate
  • internal leakage
    • install a unhardended steel spacer
    • steer until the axle stop contacts the spacer
    • 20lbs force on the steering wheel while recording internal flow rate of the gear (should less than 1gpm)
  • poppet setting test
    • turn steering wheel full left or right position, holding steering wheel with 20lbs of force
    • pressure should drop 200-400psi less than the relief pressure when the steering 1/8” closes to the axle pad

Air conditioning

• Celsius to Fahrenheit C = (F - 32) * 5 / 9
• heat quantity (BTU, J) tells how much energy a substance contains
• latent heat - the energy is absorbed or released when changes of state occur
  • 1 pound of water requires the latent heat of evaporation (970 BTU) to change to water vapour
  • 1 pound of water vapour requires the latent of condensation (970 BTU) to change to water
  • R-134a requires 90 BTU for its state change @ 5F
• the higher the pressure that surround the substance, the higher the temperature at which the substance changes state and vice versa
• saturated conditions means that there is only pure R-134a liquid and pure R-134a vapour present in the closed container
• superheat
  • evaporator
  • Line - Gauge = Superheat
  • suction side
  • vapour
  • blue gauge
  • low side (super heat)
  • bigger line
• subcooling:
  • condenser
  • Gauge - Line = Subcooling
  • liquid
  • red gauge, red hose
  • high side (subcooling)
  • small size gauge
• before turning unit on, crack open the line at the gauge set to purge all the moisture out
• NC - thermostatic switch: [32F, 38F]
  • <= 32F (freeze point) compressor not run; >= 38F compressor run
  • sensing caplillary tube @ evap core, if it’s warm, sw is closed, clutch is engaged
  • use to trigger evap defrost, also protect compressor running low psi @ suction side
• NO - low pressure switch: [24 psi, 34psi]
  • <=24psi (~32F @ evap) compressor not run; >=34psi compressor run
  • sense pressure @ accumulator or dryer, if pressure is 24psi, sw is closed, clutch is engaged
  • protect compressor running @ low psi @ suction side
    • lack of refrigerant
    • block txv or orifice
    • ambient temperature is cold, which can cause psi drop, thus turning ac system
• NC - high pressure switch [350psi, 250psi]

  • =350 psi contacts open, and close when pressure drop below 250psi

  • sense pressure @ accumulator or dryer
  • set lowser than pressure relief, thus preventing refrigerant relief to atmosphere
• binary switch = hi + lo pressure switch
  • located at dryer
• trinity switch = hi + lo + shutter fan
  • low pressure NO sw: [24psi, 34psi]
  • high pressure NC sw: [350psi, 250psi]
  • shutter fan: 35~80 psi turn on engine fan for certain seconds depending on road speed
• air conctrol system
  • intergated: control how much coolant flow to heater core, air always flow through heater core and evap core
  • manual: control how much air flow through theater core and evap core, coolant always flow to heater core @ maximum flow
  • common terms: floor outlet, panel outlet, defroster outlet, refresh air intake, cab recirculation
• troubleshoot
  • overall check all interity of the wiring
  • check clutch is engaged, then check fuse if need
  • use a fuse jumper override the low pressure switch, if ac start working
    • faulty low pressure switch
    • low refrigerant
    • refrigerant is too cold, or ambient temperature is too cold
  • check air duct temperature, and observe the HVAC cycles
• leak test
  • use nitrogen to pressurize the ac system, then use soap test, maximum 250 psi
  • do not use compressed air or refrigerant charged with red dye
• the effect of moisture in ac system
  • air is not condensed, causing spike in pressure
  • air + refrigerant + oil = sludge which can freeze at the orifice, thus blocking refrigerant

Lubrication system

• viscosity of oil is the measure of oil’s resistance to flow
  • low viscosity means easy to flow
  • high viscosity means hard to flow
• viscosity index refers to the rate that oil will change viscosity as the temperature changes
  • oil with high viscosity index would experiences small change in viscosity
• oil function: reduce wear, absorb heat, clean, sealant
• if engine oil contains silicon, check air filter seals and air intake connections for leaks
• detergents help prevent deposits from forming on internal engine parts
• dispersants keep deposits suspended in the oil
• oxidation inhibitors prevent oil from absorbing excess oxygen, which may build of of sludge
• oil classification
  • si - the standard - spark ignion engines
  • ci - the commercial - diesel engines
• take sample oil by mid-stream approach; oil should be hot, and wear particles are still in suspension
• oil analysis show high in silicon (dirt) : air induction system, air filter
• check oil level after engine has been stop for several minutes.
• high oil level: oil foaming may occur; heat can build up since the oil film quality is reduce because of foaming
• low oil leve: heat can build up because lack of oil film at the bearing surfaces, metal to metal contact may occur

Oil pressure

• pressure is high when the oil is cold, new, high viscosity
• pressure decreases when the oil is hot, contaminated, and diluted.
• oil pressure history can provide clues as to the stat of the internal bearing clearance
• low oil pressure
  • internal engine parts’ clearance is significant; noise may confirm the increased clearances
  • a faulty pressure regulating valve can cause low oil pressure
  • engine size during operation can happened if oil pressure is low
• high oil pressure
  • high oil viscosity
  • incorrect oil pump, pressure regulating valve spring, or oil sending unit
  • pressure relief valve not opening & pressure regulating valve is stuck closed
• install mechanical pressure gauge at the main oil gallery to verify dash gauge
• computer can reduce engine speed based on signal from the oil pressure sensor

Oil filter

• full flow oil filter - 25-60microns; shunt type allow unfiltered oil pass
• bypass oild filter - 10 microns; cleaning oil device, not supply oil to system
• oil cooler: oil to air, oil to cooler, bypass oil when it’s cold
• acid sulphuric in oil can indicate engine blow by
• air, water vapour, and oil mixer can create sludge. Crankcase vent system is used to remove these contaminant
• oil need to warm enough to transfer water vapour to crankcase vent system.
• crankcase ventilation systems
  • draft tube: a modified road draft system which has an outlet tube, and an inlet filter on the valve cover
  • pcv - positive crankcase ventilation - vent water vapour back to the intake
    • vent back to a pleated depth type filter
    • or use centrifuggal action to separate oil from vapour
• if crankcase vent system fail, following symtoms will be seen
  • excess crankcase pressure
  • crank shaft seal, turbo seal leakage
  • increase oil consumption

Oil cooler service

• an internal leaks in the cooler could allow oil to pass into the cooling system as pressure in lubrication system is higher than cooling system
• some oil cooler can use a termostat to regulate oil flow opening.
• pressure test oil cooler, immerse the cooler in the warm water, and watch for air bubbles
  • one opening is blocked off, the other is connected to an adjuster air regulator
• high oil temperature
  • oil dilution with diesel
  • metal to metal contact
  • incorrect oil viscosity
  • when the oil inlet and outlet temperature are very similar, it can be a plugged coolant line or coolant core

Notes

• DD Series 60: EUI
• DD 15, DD 16, common rail infection system