Will a Clogged PCV Valve Cause an Oil Leak?

A clogged PCV valve can cause engine problems.

The positive crankcase ventilation valve (PCV) is used to reduce the amount of emissions that a vehicle releases into the atmosphere. When the PCV valve becomes clogged, the engine can develop a number of problems, including an oil leak.

PCV Valve Operation

During combustion, some amount of engine exhaust escapes around the piston rings instead of exiting through the exhaust valve. When the exhaust pressure inside the engine reaches a certain point, the PCV valve opens and returns the exhaust into the combustion chamber. Without a PCV system, the exhaust would be vented into the atmosphere without passing through the exhaust.

Clogged PCV Valve

When a PCV valve stops working, pressure builds up inside the valve cover. This pressure can cause a number of problems for the engine, including an oil leak, particularly at the valve pan gasket. Clogged PCV valves may make an engine run poorly, decrease gas mileage and increase vehicle emissions.

PCV Valve Replacement

Replacing a PCV valve on most vehicles does not require tools, though pliers can make the job easier. The valve simply slips out of its housing, and the hose attached to the valve is then slipped off. The new valve is then inserted into the housing and the hose reattached. If needed, engine oil can be used to lightly lubricate the valve to ease insertion.

References

• AA1 Car: Library, Positive Crankcase Ventilation (PCV)
• Trust My Mechanic: Valve Cover Gasket