The smoke from a diesel engine indicates that something is wrong. This should be taken as an indication that there is a problem that will shorten the life of your engine. A diesel engine in good condition should not produce smoke of any color.
BLACK SMOKE: It is the most common, it is an imbalance, this means that there is too much fuel and not enough oxygen to burn the fuel supplied. The black smoke is full of diesel particles that could be burned as fuel. Either way you look at it, if a truck with diesel engine emits black smoke it means that diesel performance is not giving the required mileage per gallon; and this is something that every company, truck driver or owner look for.
The most common causes for a truck producing black smoke are: defective injectors, injector pump, a damaged air filter (this is the reason why enough oxygen to work normally is not sent), having a damaged EGR valve (it can cause obstruction in all valves), the turbocharger is not working well. Some of these are easy to fix, so a truck driver does not have to worry a lot about this.
WHITE SMOKE: It means that the fuel being injected into the combustion chamber does not burn properly. The most common causes that produce white smoke may vary from something as simple as the low compression engine or presence of water in the fuel creating bad synchronization that fuel arrives safely to the pump and operating properly.
BLUE SMOKE: It means that the oil engine is burning. This is a mechanical problem and it is a bigger problem if we talk about economics. The engine oil should not meddle in areas where it can burn; if an owner of a truck has this problem means that there could be a faulty injector pump, allowing the oil mixed with diesel. The use of cylinders and piston rings, allow the oil to seep out where it should not or probably you have a very simple problem like putting too much oil in the engine.
Any problem you can contact your mechanic and avoid to stay lying on the road or if you wish you can call me to check your engine at: 909-591-1979.