* Burning Oil: This is a very common cause of smoke. Blue or bluish-grey smoke usually points to burning oil. The sources could be:
* Worn Piston Rings: Allow oil to seep into the combustion chamber.
* Worn Valve Stem Seals: Allow oil to leak past the valve stems.
* Leaking Valve Cover Gasket: Allows oil to leak onto hot engine parts, causing it to burn off.
* A cracked or damaged PCV valve: The positive crankcase ventilation (PCV) valve prevents excessive crankcase pressure buildup. A malfunction can lead to oil being drawn into the intake manifold and burned.
* Burning Coolant: White or whitish-grey smoke often indicates a coolant leak into the combustion chamber. This could be due to:
* A blown head gasket: This is a serious problem requiring significant repair.
* Cracked cylinder head: A crack in the cylinder head can allow coolant to mix with the combustion gases.
* Cracked engine block: Less common, but a serious issue.
* Burning Fuel: Black smoke typically signifies that the engine is running rich (too much fuel). Possible causes include:
* Faulty fuel injectors: Injecting too much fuel.
* Malfunctioning mass airflow sensor (MAF sensor): Providing incorrect air/fuel mixture readings to the engine computer.
* Problems with the oxygen sensor (O2 sensor): The O2 sensor helps regulate the air/fuel mixture.
* Clogged air filter: Restricting airflow.
* Other: Other less common causes include:
* Transmission fluid leak: Although less likely, a transmission fluid leak onto hot engine components could produce smoke.
* Electrical fire: Though rare, an electrical short could cause smoke.
To diagnose the problem accurately:
You need a professional mechanic to inspect your engine. They can perform a compression test, leak-down test, and visual inspection to pinpoint the source of the smoke. Simply observing the color of the smoke provides clues, but it's not definitive. Ignoring the problem could lead to significant engine damage.
