* Worn piston rings: This is a common cause. Worn rings allow combustion gases to escape into the crankcase, pressurizing it and forcing oil out through the breather.
* Worn valve guides or seals: Leaking valves can also allow combustion gases to enter the crankcase.
* Blown head gasket: A serious issue where combustion pressure escapes into the cooling system or crankcase. This is often accompanied by other symptoms like overheating, loss of coolant, or milky oil.
* PCV valve problems: The Positive Crankcase Ventilation (PCV) valve helps regulate crankcase pressure. A malfunctioning PCV valve can lead to excessive pressure and oil leaks.
* Excessive crankcase pressure: This could stem from any of the above issues, or even a clogged breather system.
Ignoring this problem can lead to catastrophic engine damage. The burning oil contaminates other engine components, reducing lubrication and potentially causing a seizure.
What to do:
1. Stop driving the car immediately. Continued operation will worsen the problem.
2. Inspect the oil. Is it milky (indicating coolant mixing with oil)? Is the level significantly low?
3. Consult a qualified mechanic. They can properly diagnose the underlying cause of the smoke and recommend the necessary repairs. This is not a DIY project for most unless they have significant engine repair experience.
Smoking from the valve cover breather is a clear sign of internal engine problems, and professional attention is crucial to prevent extensive and costly repairs later. Don't try to "smoke it out" – that's just a dangerous misunderstanding of the problem.
