Valve Stem Seal Catalogs

What is Valve Stem Seal?
The purpose of the valve stem seal is to prevent the oil from the cylinder head entering the combustion chamber. It plays a critical role in controlling valve lubrication as well as oil consumption. If valve stem seal fail, this will cause the engine to suck oil down the guides and into the cylinders. 

Reasons of fail Valve Stem Seals
1. Worn
2. Cracked
3. Missing
4. Improperly installed