KIT-GASKET 6V6391 - Caterpillar

All EnginesDuring the operation of any engine, each valve lifter wears to an exact fit with the specific cam it runs against. This relation between a lifter and its cam is very similar to the fit of a bevel gear and pinion set, and the two must be kept together.
For this reason, it is very important to install lifters correctly during engine service work. When the original camshaft and lifters are to be used again, each lifter must be installed in its original location so it runs against the same cam. During engine disassembly, put a mark on each lifter for positive identification of the correct sequence when they are installed again. Never permit the lifters to become mixed and install them in the wrong sequence.
Do not damage contact surfaces when marks are put on lifters.
When a new camshaft is installed, use new lifters. When a lifter has worn to fit the cam of one shaft, do not install it to run against the cam of a new or different camshaft. New lifters can be installed with a used camshaft if necessary.
In addition to correct installation of lifters, they must have good lubrication when the engine is first started. During engine assembly, be sure to put enough engine oil on the lifter assemblies, the cams of the camshaft, and all bearing surfaces to give the necessary lubrication. This will prevent damage to friction surfaces at the time the engine is started, before oil can flow through the system.
These rules, when carefully followed, will extend the service life of camshafts and valve lifters for maximum engine performance.