could have bad o rings
If white smoke is coming out of the exhaust when the engine is warmed up , it sounds like engine coolant is getting into an engine cylinder
A blown head gasket can make one smoke or the engine is shot.
the engine is running
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.
The smoke you see may be moisture/steam. The heater core is probably leaking engine coolant. If the "smoke" has a sweet smell to it, it's engine coolant. More info about the vehicle such as model and year would help.
black smoke or blue smoke. has it affected the running of the car. sounds to me like you need new valve guide seals these seals prevent oil from the tappets running down the valve stems and into the combustion chamber
This engine could have burnt rings in it. There also could be an old leak which is running down on the manifold which would cause the engine to smoke.
Moisture in the exhaust, or a cold running engine.
White smoke = Coolant leak, head gasket is the likely culprit. Blue smoke = Engine burning oil. Black smoke = Engine running too rich, wasting fuel.
its probably burning oil, if the smoke is white. if the smoke is black, it means its running rich. if the smoke is white, you have serious internal engine problems
If it stops after a minute or two, it was condensation. If it continues the whole time the engine is running, it's smoke.
Assuming this is a gasoline engine, it is running rich from excess gasoline.