How does a Valve Cover Gasket Work?
Valve stem seals prevent oil from contaminating the air/fuel mixture in the engine’s combustion chamber. They also prevent intake and exhaust gases from contaminating the oil in the cylinder head and the rest of the engine.
Valve stem seams are like any other round seal, only much smaller. The inside diameter fits over the valve stem. The outside diameter of the seal fits over the valve guide. Together, they form a tight seal between the crankcase and combustion chamber as the engine’s valves open and close.
How are Valve Stem Seals Made?
Like other circular seals found on a vehicle, valve stem seals often feature small springs that allow them to fit tightly over the parts they are designed to seal. Valve stem seals are mass-produced out of rubber, soft plastic, or nitrile on factory molding machinery.
Though you may not need to remove the cylinder head to complete a valve stem seal replacement, the job often requires special tools like a valve stem seal tool and a valve spring compressor.