Valve Guide Reaming
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Using a dial indicator, measure the valve stem-to-guide clearance. Position the tip of the dial indicator at the top of the valve guide.
Valve stem-to-guide clearance may also be obtained by using a micrometer to measure the valve stem diameter and a ball type measuring gage to measure the guide bore.
- A valve stem (1) and guide (2), with excessive clearance, must be replaced or the cylinder head replaced. Refer to Engine Mechanical Specifications (RPO LY5 VIN J) or Engine Mechanical Specifications (RPO LC9 VIN 3) or Engine Mechanical Specifications (RPO LY2 VIN C) or Engine Mechanical Specifications (RPO LH6 VIN M) or Engine Mechanical Specifications (RPO LMG VIN 0) or Engine Mechanical Specifications (RPO LY6 VIN K) or Engine Mechanical Specifications (RPO L76 VIN Y) or Engine Mechanical Specifications (RPO L92 VIN 8) .
- 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. A valve stem with a diameter less than 7.95 mm (0.313 in) must be replaced.
If the valve stem diameter is within specifications, and the stem-to-guide clearance is excessive, the cylinder head must be replaced.
NOTE:
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.
NOTE:
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.