Valve Guide: Testing and Inspection

CLEARANCE
1. Check the valve stem to guide clearance using a hole gage and an outside micrometer.
2. Measure the valve guide inside diameter with a hole gage, crossways to the engine, at both the top and 10 mm (0.39 inch) up from the bottom of the guide, measuring gage each time with micrometer. A standard size valve guide is 5.979 mm (0.235 inch).
3. Measure the valve stem diameter with the micrometer and subtract from the greater of two guide measurements to obtain the maximum clearance.
4. If the clearance is greater than 0.12 mm (0.0005 inch) and a new standard diameter valve stem will not bring the clearance within specifications, the cylinder head must be replaced.
5. Valve guide wear at the bottom 10 mm (0.39 inch) of the valve guide is not significant to normal operation.