Engines trouble shooting by the color of smoke

Generally a diagnosis as to what’s wrong with a diesel engine can be identified by the colour of smoke coming from the exhaust pipe. There are three basic colours - ‘Black’, ‘White’ and ‘Blue’.

Black Smoke
This is due to an air to fuel ratio imbalance, either the fuel system is delivering too much fuel or there’s not enough clean air (oxygen) for complete combustion, a few things to look for are:-
A. Faulty injectors
B. Faulty injector pump
C. Dirty or blocked air cleaner
D. Turbocharger faulty
E. Problems within the cylinder head or inlet valves not seating due to a build up of carbon
F. Over fuelling
G. High altitude operation

White Smoke
This is normally caused by the fuel being injected and not burning correctly. The smoke will ‘Sting’
your eyes. This problem can be caused by any of the following:-
A. Injection pump timing incorrect
B. Fuel starvation to the injection pump
C. Low engine compression
D. Water in the fuel
E. Water entering the combustion chamber
F. Faulty head gaskets and cracked cylinder liners & heads are a common cause of water entering the cylinder.

Blue Smoke
Blue smoke will be emitted when the engine is burning oil, this can sometimes be accompanied by oil coming out of the end of the exhaust pipe, common problems are:-
A. Worn cylinder liners or piston rings
B. Piston rings sticking
C. Faulty valves stem seals
D. Engine over full with engine oil
E. Dilution of the engine oil with fuel
F. Wrong ‘Grade’ of oil, I.E. Too thin
G. Too good a quality of oil in an old ‘Classic’ engine, I.E. Using semi synthetic or fully synthetic oil.
E. The engine not being ‘Worked’ hard enough, all diesel engines need hard work otherwise the cylinder bores can become ‘Glazed’.
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