Broken rings, rings not installed on pistons correct, No valve seals
Bad are worn valve guides.
If an engine is running rich, it is receiving and burning too much fuel and that will yield black smoke. If an engine is somehow burning oil, that will yield white smoke.
Smoke can come from several things. White smoke when first starting on a cold day is normal. Black smoke indicates the wrong fuel/air mixture. Blue smoke indicates that the engine is burning oil.
Blue smoke is burning oil.
Year/make/model would help with a more specific answer, but in general... black smoke is a sign of a excessively rich fuel condition, blue burning oil, white burning coolant.
If it blows blue smoke when starting up, that is usually the valve guides need replacing. If it constantly blows blue smoke, you are looking at piston rings. Either way oil is getting into the combustion chamber. If it's valve guides, you need to have the heads looked at, if it is rings, the bottom of the engine needs to come out.
Blue smoke, burning oil. (tired) White smoke, burning coolant. (bad head gasket) Black smoke, excess gasoline (flooding).
If black smoke is coming out of the exhaust of a 1986 Ford Ranger, it is likely burning oil. It's possible that a seal is leaking in the engine.
blue smoke comes out the tail pipe when your engine is burning oil caused by a worn engine.
Usually the engine is burning coolant.
ENGINE SMOKE Check Related link below
The black smoke that a diesel engine blows out is fuel that is unburned. The black smoke can be caused from over-fueling, poor fuel quality, or dirty or worn fuel injectors.
because the fan belt is burning