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Observing the colour of exhaust smoke of your diesel engine
is on of simplest ways to tell how your engine is performing,
and it can indicate serious conditions that may exist before
damage can occur. A diesel engine's exhaust should be clear
with the possible exception of sudden acceleration or extra
loading or, idling or running under low loads for prolonged
periods. Any other smoke or smoke condition is a sure sign
of problems. The colour of the smoke is a useful guide to
help determine the source of the trouble.
The following chart is a guide to smoke colour and a list
of possible causes
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BLACK SMOKE |
Restricted
air flow (dirty / obstructed air filter; plugged exhaust;
restrictions in exhaust system; defective turbo / supercharger);
Overload; Improper injection (poor atomization, injector dribble,
late injection) |
BLUE
SMOKE
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Worn
or stuck piston rings; worn valve guides and stems; high crankcase
pressure; worn / supercharger oil seals. |
| WHITE
SMOKE |
Misfiring
cylinders; water in fuel; air in fuel; water in cylinders
(blown head gasket, cracked head or liner); lack of compression. |
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Major sudden failures are
rare and are often the result of an underlying problem that
has been left unchecked. Components that do fail suddenly
are often easily rectified.
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Engine
will not turn when attempting to start
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Battery
terminals corroded, and or poor connections, faulty battery
or discharged - Faulty connection/s in starter circuit - Faulty
starter solenoid - Faulty starter motor. Bad or corroded cable
connections |
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Engine
turns, but will not start
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Fuel
tank empty - Battery condition (see above) - Air filter clogged
- Poor cylinder compression - Ignition system damp or wiring
fault - Faulty spark plugs - Choke incorrectly adjusted or
worn - Fuel line fault, or fuel pump |
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Noisy starter
motor
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Starter
motor mounting bolts loose - Internal damage to starter motor
- Flywheel teeth damaged |
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Engine
starts, but then cuts out
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Ignition
system wiring fault - Tappet settings incorrect - Uneven cylinder
compression - Fuel line or fuel pump faulty - Idle speed incorrect
adjustment - Choke mechanism faulty or incorrectly adjusted
- Blocked carburettor jets - Vacuum leak inlet manifold or
carburettor hoses |
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Uneven
engine idle speed
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Incorrect
setting for idle speed - Air filter blocked - Fuel system
air-locked - Incorrect tappet adjustment - Faulty spark plugs
- Vacuum leaks, as above - Carburettor jets blocked - Low
or uneven cylinder compression. |
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Engine
misfires
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Distributor
cap faulty - Faulty fuel lines, pump, Incorrect tappet adjustment
- Cylinder compression low or uneven - Vacuum leaks as above
- Fuel filter clogged - Fuel tank vent blocked - Faulty HT
leads |
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Engine
stalls
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As
above |
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Engine
runs on after switching off
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High
carbon build up in engine - High engine operating temperature
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Oil pressure
warnings
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Low
oil level - Incorrect oil grade - Oil pressure sender unit
faulty - Worn engine bearings - Faulty oil pump - Excessively
high engine temperature - Oil relief valve defective - Oil
filter clogged. |
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The links below give more
information on ingintion and engine starting problems.
Battery polarity and coil
connections.
Reversing the battery polarity
and correct coil connections. Generally done when an alternator
is fitted in place of the dynamo. Incorrect coil polarity
can cause poor hot engine performance and stalling. I know
this is a car link and I thank MGCars for the information
but it is totally valid for us.
http://www.formatc.org/mgb/articles/ignition.htm
http://www.diyfixit.com/motor/faultfinding/enginestart/enginestart4.htm
http://library.thinkquest.org/C006011/english/sites/ottomotor.
http://www.keveney.com/otto.html
http://library.thinkquest.org/C006011/english/sites/mehrzylinder
http://library.thinkquest.org/C006011/english/sites/diesel.
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