* Burning Oil: This is a very common cause. Smoke that's bluish-gray or blueish-white, especially on startup or acceleration, usually indicates burning oil. Possible culprits include:
* Worn Piston Rings: Allow oil to seep into the combustion chamber.
* Valve Stem Seals: Worn seals allow oil to leak past the valves.
* Worn Valve Guides: Similar to valve stem seals, worn guides let oil into the combustion chamber.
* Leaking Crankshaft Seal: Allows oil to leak into the engine.
* Blown Head Gasket: In severe cases, a blown head gasket can allow oil to mix with coolant and enter the combustion chamber.
* Burning Coolant: White smoke, often accompanied by a sweet smell, suggests coolant is burning. This usually points to:
* Blown Head Gasket: A very common cause.
* Cracked Cylinder Head: A crack allows coolant to leak into the combustion chamber.
* Cracked Engine Block: Less common, but possible.
* Burning Fuel: Black smoke, particularly under acceleration, typically indicates a rich fuel mixture. This could be due to:
* Faulty Fuel Injectors: Injecting too much fuel.
* Clogged Air Filter: Restricting air flow, leading to a rich mixture.
* Mass Airflow Sensor (MAF) Problem: An inaccurate MAF sensor can cause the engine to run rich.
* Throttle Position Sensor (TPS) Issue: A malfunctioning TPS can also lead to a rich fuel mixture.
To diagnose the problem:
You need to have a mechanic inspect your car. They can perform a compression test, a leak-down test, and visually inspect the engine for leaks to determine the source of the smoke. Simply observing the color of the smoke and when it appears (startup, acceleration, idle) will give them valuable clues. Ignoring the problem could lead to serious engine damage.
