The exhaust of a serviceable engine is almost colorless. A barely perceptible light white smoke comes out of the exhaust pipe, the intensity of which increases when you sharply press the gas pedal.
In frosty weather, a serviceable car leaves rather thick clouds of white steam behind it (not to be confused with smoke!), indicating complete combustion of the fuel.
Inhaling exhaust gases for a long time is more expensive for yourself. We turn off the engine. But it's not the end yet. It is worth examining the inner surface of the oil filler cap. The presence on it of traces of a foamed emulsion of a dirty yellow color is a very alarming symptom, indicating leakage of antifreeze into the oil. After removing the cap of the expansion tank or radiator, inspect the antifreeze. Warning: To avoid injury, do this with a cold engine! An oil film on the surface of the antifreeze, just like foamed motor oil, are harbingers of an urgent engine repair.
That, perhaps, is all. We have thoroughly examined "patient", walking literally from the tip of the nose to the tail. And during the inspection they used not expensive equipment that was inaccessible to most motorists, but what was given to us by nature: sight, hearing, smell and, of course, the mysterious "gray matter".
Oily annular belt 6-8 mm wide on the outer surface of the car exhaust pipe ("mourning headband") due to increased oil consumption. Engine overhaul is inevitable.
Black smoke
Sign of incomplete combustion of fuel. The feed system prepares a very rich mixture and needs to be adjusted.
Blue smoke (purple) shade
Sign of increased oil consumption. The engine requires replacement of valve stem seals or repair of the cylinder-piston group.
Thick white smoke
A symptom of a burnt cylinder head gasket. Coolant enters the combustion chamber.
Exhaust-smelling smoke from a removed crankcase ventilation pipe (breather) engine.
A sign of a breakthrough of exhaust gases into the oil sump due to increased clearances in the cylinder-piston group.