Some of the engine problems can be guessed directly from the color of the smoke from the exhaust pipes. Here’s how to “read” its colors.
WHITE SMOKE
You should notice this during winter power-ups or after a long period of not using the boat. Usually the white color is given by the evaporation of moisture or water deposited in the drain pipes. To be more “catastrophic,” it could also indicate water in the cylinders due to dirty fuel, or even a stuck piston. In this case, carefully check the engine temperature. Pay attention to cleaning the filters, including the air filter.
GRAY SMOKE
It is usually noticed when the engine has not been used for a long time and the whole power circuit might be dirty. The fuel and injectors should be checked. Since this is usually an intermediate condition between black and white smoke, the advice is to have the powerplant carefully serviced.
BLACK SMOKE
If the smoke occurs only at the first ignition after a long time of inactivity, there should be no problem; it is usually combustion of charcoal present in the fuel. If, on the other hand, the black smoke is frequent and persists even while sailing then the problems may be more serious. Indicates a state of engine deterioration, investigate the fuel system, clean the injectors and check the filters, including the air filter.
BLUE SMOKE
Indicates above-normal oil combustion. This obviously also results in lower lubricant pressure in the circuit and obviously a decrease in the level. To burn, oil slips inside the combustion chamber of the pistons, and this results in decreased engine output and clogged valves, given by the residue of the burned oil. Blue smoke is one of the main signs of engine wear, the overhaul to be done should be thorough.
