Valve Guide Reaming
WARNING: This page is about a different car, the 2003 GMC Envoy XL and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
- 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.
- 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.
- Measure the valve stem-to-guide clearance using a dial indicator. 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 components replaced.
Refer to ENGINE MECHANICAL SPECIFICATIONS .
- 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.
- A valve guide that is worn and has excessive stem-to-guide clearance should be reamed and valves with oversize stems installed.
- 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 valve guide must be reamed oversize and a valve with oversize stem installed.
- Ream the valve guide using the J 37378-1.
- Clean the guide bore of all metal shavings and debris.
- Install the valve (2), with oversize stem, into the cylinder head (1).
- Inspect the valve for the proper fit.
Move the valve back and forth in the guide. The valve should move freely with no resistance or drag.