Given the fact that this is a highly professionalized position, and it entails the use of some special tools and apparatus, the procedure known as a valve job, which refers to the servicing of the valves, valve seats, and valve guides should only be done by a master mechanic. A home mechanic should detach the heads and undertake preliminary scrubbing and checking before taking them to a dealer's service station or automotive machine for servicing. Carrying out the inspection enables the checker to get an insight on the state of the
Cylinder Head and the valvetrain components, know the work that needs to be done, and the new components to be expected from an automotive machine shop. The Power train or the dealer service department or automotive machine shop will then remove valves and springs, recondition or replace valves, or valve seats, recondition or replace valve guides, check and replace valve springs, spring retainers or valve stem locks and replace the valve seal with a new one, assemble the valve components, and verify the correct installed height of the spring. Further, the surface of cylinder head gasket will be ground if warped is the case. After the valve job which is done by a professional the cylinder head will be as good as new. On the return, it is necessary to wash again the cylinder head before putting it on the engine in order to remove metal debris and abrasive grit remained either after the valve service or cylinder head resurfacing, and to blow through all oil holes and ducts, if possible with compressed air.