Valve Stem Seals for American Diesel Engines
OEM replacement valve stem seals for Cummins, Caterpillar, Detroit, Mack, CaseIH and John Deere engines
Valve stem seals are mostly metering seals. Positive stem seals are designed to leak or meter oil past the seal at a precisely metered rate. This is necessary for controlled lubrication to limit wear and scuffing of the valve stem and guide and reduce oil entering the combustion chamber. Earlier engines didn’t use valve stem seals but are now required by virtually all diesel engine manufacturers to comply with emission control laws.
Common types in use are Metal Clad, Top Hat and Oil Shields. The Metal Clad and Top Hat are positive (attach directly to the valve guide). Umbrella or Oil Shields attach to the valve stem or rotocoil. The Metal Clad mostly utilizes a silicon or viton wiper with a garter spring. The Top Hat (Viton seal) is widely used in late model diesels. It incorporates a valve spring seat in the seal carrier body and attaches to the guide for positive location.
Normally stem seals are provided in the VRS gasket or may be procured separately.