Diesel Engine Faults
(1) Starter motor won’t crank the engine.
(2) Starter motor cranks the engine but it won’t start.
(3) Engine starts but it won’t run smoothly (Engine misses)
(4) Engine overheating.
(5) Knocking sound in the engine.
(6) Loss of engine power.
(7) Abnormal engine oil pressure.
(8) Excessive engine oil consumption.
(9) Excessive engine vibration.
(10) Excessive fuel consumption
(11) Dense smoke at the engine exhaust
(1) Starter motor won’t
crank the engine.
Possible Causes :
1. Engine jammed.
2. Transmission not in neutral position.
3. Seat belts not fastened.
4. Battery
discharged, terminals loose or corroded.
5. Damaged or disconnected battery cables.
6. Starter motor defective or pinion jammed in fly
wheel.
7. Starter switch defective or circuit open.
(2) Starter motor cranks the engine but it won’t start.
Possible Causes :
1. Incorrect starting procedure.
2. Heater plugs defective.
3. Battery
discharged.
4. Engine oil too thick.
5.
Fuel system defects :
(A) No or insufficient
fuel in the tank.
(B) Contaminated or poor quality fuel.
(B) Contaminated or poor quality fuel.
(C)
fuel line leaking, blocked or with air bubbles.
(D) Fuel tank breather
blocked.
(E) fuel filters
blocked or fuel feed pump inoperative.
(F) Fuel injector pump
defective or timing incorrect.
(G) Injectors blocked
or fuel spray unsatisfactory.
(H) Fuel inlet pipes
to injectors leaking.
6.
Insufficient cylinder compression :
(A) Piston rings,
cylinders worn out.
(B) Compression leaks
between cylinder head and block due to damaged or improperly tightened gasket
(C) Improper
valves or valve operation :
(a) Valve timing incorrect
(b) Insufficient valve clearance
(c) Valves, valve seats worn, burnt or damaged.
(d) Valves stuck open, bent push rod or broken
spring.
3. Incorrect
starting procedure.
4. Heater plugs
defective.
5. Battery
discharged.
6. Engine oil too
thick.
(3) Engine starts but it won’t run smoothly (Engine misses)
Possible Causes :
1.
Fuel system defects :
(A) No or insufficient fuel in the tank.
(B) Contaminated or
poor quality fuel.
(C) fuel line leaking,
blocked or with air bubbles.
(D) Fuel tank breather
blocked.
(E) fuel filters
blocked or fuel feed pump defective.
(F) Fuel injector pump
defective or timing incorrect.
(G) Injectors blocked
or fuel spray unsatisfactory.
(H) Fuel inlet pipes
to injectors leaking.
2.
Insufficient cylinder compression.:
(A) Piston rings,
cylinders worn out.
(B) Compression leaks
between cylinder head and block due to damaged or improperly tightened gasket.
(C) Improper valve operation.
(C) Improper valve operation.
(a) Valve timing incorrect.
(b) Insufficient valve clearance.
(b) Insufficient valve clearance.
(c) Valves leaking
(worn, burnt or damaged).
(d) Valves stuck open,
bent push rod or broken spring.
3. Engine overheated.
4. Restricted exhaust.
(4) Engine overheating.
Possible Causes :
1.
Cooling system defects :
(A) Insufficient or no
coolant.
(B) Leakage of coolant
to outside through radiator, radiator pressure cap, expansion tank, radiator
hose, hose connections, water pump seals, drain plug etc.
(C) Leakage of coolant
through cracked or warped cylinder head, cylinder block or damaged cylinder
head gasket.
(D) Fan drive belt
loose or slipping with oil.
(E) Fan blades
warped causing poor air flow.
(F) Fan drive clutch
or motor defective.
(G) Radiator cooling
and coolant flow restricted due to corrosion.
(H) Thermostat stuck
or improperly installed.
(I) Defective water
pump which does not circulate enough water.
2. Temperature gauge or indicator
defective.
3. Exhaust system obstructed (High exhaust back
pressure.)
4. Improperly operating emission
controls.
5. Injector pump timing retarded or valve
timing incorrect.
6. Engine oil level low or oil filters blocked.
7. Oil pump worn out or oil pressure relief
valve leaky.
8. Main
or big end bearings worn out.
9. Piston rings or bearings too tight causing
excessive engine friction.
10. Brakes dragging or clutch slipping.
11. Overloading of the engine.
12. Continuous driving in low gears.
13. Hot climate conditions or high altitude
operation,
(5) Knocking sound in the engine.
Possible Causes :
1.
Combustion knocks :
(A) Improper
quality of fuel.
(B) Fuel injector pump
defective (Timing advanced)
(C) Incorrect valve
timing.
(D) Injector pressure
reduced.
(E) Engine overheating.
(F) Excessive carbon
deposits in cylinders.
2.
Mechanical knocks :
(A) Valve clearance
excessive.
(B) Broken, worn or
seized piston rings.
(C) Incorrect bearing
clearances.
(D) Excessive
crankshaft end play.
(E) Damaged main or
connecting rod bearing
(F)
Flywheel, pressure plate loose
(6) Loss of engine power
Possible Causes :
1. Fuel
system defects :
(A)
No or insufficient fuel in the tank.
(B) Contaminated or poor quality
fuel.
(C) fuel line leaking, blocked or
with air bubbles.
(D) Fuel tank breather blocked.
(E) fuel filters blocked or fuel feed
pump defective.
(F) Fuel injector pump defective or
timing incorrect.
(G) Injectors blocked or fuel spray
unsatisfactory.
(H) Fuel inlet pipes to injectors
leaking.
2.
Insufficient cylinder compression :
(A) Piston rings,
cylinders worn out.
(B) Compression leaks
between cylinder head and block due to damaged or improperly tightened gasket
(C) Improper
valves or valve operation :
(a) Valve timing incorrect.
(b) Insufficient valve clearance.
(c) Valves, valve seats worn, burnt or damaged.
(d) Valves stuck open, bent push rod or broken
spring.
3. Fouled air cleaner
4. Exhaust pipe or silencer blocked.
5. Engine overheated.
6. Excessive carbon deposits in combustion
chambers.
7. Defective torque converter (Auto gear box)
8. Use of thick engine oil.
9. Excessive rolling resistance due to smaller diameter
tires, dragging brakes or wheel misalignment.
(7) Abnormal engine oil pressure.
Possible Causes :
1. Low engine oil pressure :
(A) Engine oil level
insufficient or no oil.
(B)
Excessively thin or hot engine oil.
(C) Oil diluted or
forming.
(D) Oil filter
contaminated.
(E)Oil pressure
indicator defective.
(F) Oil pressure gauge pipe line
clogged.
(G)
Oil circulation obstructed trough pipes, oil gallery, oil pump or oil filter.
(H) Oil leaks through
broken or cracked pipe lines, pipe connections, oil gallery or oil seals.
(I) Oil pressure
relief valve leaky (Weak springs).
(J) Excessive bearing
clearances.
(K) Damaged main
or connecting rod bearings.
(L) Wrong grade
of oil for weather condition.
(M) Oil pump is
worn out.
1. High engine oil pressure :
(A) Oil pressure relief valve stuck.
(B) Excessively strong relief valve spring.
(B) Excessively strong relief valve spring.
(C) Oil line is
clogged.
(D)
Excessively thick engine oil.
(8) Excessive engine oil consumption.
Possible Causes :
1. Engine oil leaking
2. Cylinders or piston
sleeves worn out
3. Piston oil rings worn or stuck to the ring
grove
4. Valve guide oil seals worn out
5. Cylinder head gasket damaged or not tight
enough.
(9) Excessive engine vibration.
Possible Causes :
1. Engine idle speed too low.
2. Defective vibration damper.
3. Unbalanced or loose fly wheel.
4. Excessive crankshaft end play.
5. Loose or broken engine mounts.
6. Engine missing (Injectors blocked, injector pump
defective, valves defective)
7. Power output of each cylinder differs
(Injectors blocked, injector pump defective)
(10) Excessive fuel consumption
Possible Causes :
1.
Insufficient cylinder compression :
(A) Piston rings,
cylinders worn out.
(B) Compression leaks
between cylinder head and block due to damaged or improperly tightened gasket
(C) Improper
valves or valve operation :
(a) Valve timing incorrect
(b) Insufficient valve clearance
(c) Valves, valve seats worn, burnt or damaged.
(d) Valves stuck open, bent push rod or broken
spring.
2. High speed driving or continuous driving in
low gears.
3. Clogged air cleaner or exhaust pipe.
4. Engine friction high (Tight bearings and
piston rings)
5. Fuel leaks (Through fuel tank, fuel line or
connections)
6. Injector pump defective (Timing too
advanced, high idle speed, calibration out)
7. Fuel injectors defective (Injector opening
pressure low, nozzles clogged, spray unsatisfactory)
8. Clutch slipping or brakes dragging.
9. Excessive rolling resistance due to,
(A) Incorrect wheel alignment.
(B) Under inflated tires.
(C) Under size rims.
9. Excessive rolling resistance due to,
(A) Incorrect wheel alignment.
(B) Under inflated tires.
(C) Under size rims.
(11) Dense smoke at the engine exhaust
Possible Causes :
1. Engine overloaded
2. Air filter blocked
3. Piston rings, cylinders worn out
4. Fuel injector pump defective (worn or
calibration, phasing out)
5. Fuel injectors defective (Fouled, needles worn,
pressure adjustments out)
6. High pressure fuel line to injectors loose.