Valve Guide: Service Precautions

Valve Stem-to-Valve Guide Clearance Specifications
In the case of valve stem-to-valve guide clearance, the service clearance is intended as an aid to diagnose engine noise only and does not constitute a failure or indicate need for service. However, when overhauling or reconditioning a cylinder head, the service clearance should be regarded as having a practical working value and used as an aid when installing the valve guide and/or valve to ensure extended service life.

Component Removal
When compressing valve spring (6513) to remove push rods, rocker arms or other components, make sure piston in individual cylinder is below top dead center (TDC) to avoid contact between valve and piston.

Valve Train Reassembly
After replacement of a push rod, rocker arm or hydraulic valve tappet (6500) the engine should not be cranked or rotated until valve tappets have an opportunity to leak down to their normal operating position. The leak-down rate can be accelerated by using a valve tappet bleed-down wrench on rocker arm and applying pressure in a direction to collapse valve tappet.