Valve Guide Reaming
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- Measure the valve stem to guide clearance.
- Using a micrometer (1) measure the diameter of the valve stem (a).
- Using a ball style measuring gauge, measure the inner diameter (b) of the valve guide at the specified depth. Refer to Engine Mechanical Specifications (L83)Engine Mechanical Specifications (L86) .
- Subtract the valve stem diameter (a) from the valve guide inner diameter (b) to obtain the valve stem to guide clearance.
- If the clearance measurement between the valve stem and guide is not within specification, the valve and/or the cylinder head must be replaced. Refer to Engine Mechanical Specifications (L83)Engine Mechanical Specifications (L86) .
- Inspect the valve stems for excessive scoring, wear, or warpage.
- A valve stem that has excessive scoring (3 or 4) or wear (4 or 6) must be replaced.
- If a valve guide is worn or has excessive stem-to-guide clearance, the cylinder head should be replaced.
- Measure the valve stem diameter. If the valve stem diameter is not within specification, the valve must be replaced. Refer to Engine Mechanical Specifications (L83)Engine Mechanical Specifications (L86)
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If the valve stem diameter is within specifications, and the stem-to-guide clearance is excessive, the cylinder head must be replaced.
CAUTION:
Excessive valve stem-to-guide clearance may cause a noisy valve train, premature valve stem oil seal wear, component damage, and/or excessive engine oil consumption.
CAUTION:
Insufficient valve stem-to-guide clearance will result in noisy or sticking valves. Valves that are too tight may disturb engine smoothness or lead to component damage.