Examination
1. Determine the gap between the valve stem guide bushing and the stem (pic. 4.19a). If the value obtained is greater than the allowable value, replace the sleeve or valve (go both parts).
Pic. 4.19a. Checking the valve stem guide
Target value: inlet valve 0.02-0.05mm, exhaust valve 0.05-0.09mm.
Acceptable value: inlet valve - 0.10 mm, exhaust valve - 0.15 mm.
Replacement
2. Remove the guide sleeve in the opposite direction from the cylinder block.
3. Drill a hole for a new bushing in the cylinder head.
Repair size of the hole in the cylinder head:
- 0.05mm: 11.5-11.07mm.
- 0.25mm: 11.25-11.27mm.
- 0.50mm: 11.50-11.52mm.
Attention! The new valve guide must not be the same size as the previous one.
4. Press in the guide bush until the protrusion is: 14 mm for SOHC engines, 19 mm for DOHC engines (pic. 4.19b).
Pic. 4.19b. Correct fitting of the valve guide
Attention! Press in the guide sleeve from the top side of the cylinder block. The guide bushings for intake and exhaust valves have different lengths: for intake valves - 45.5 mm, for exhaust valves - 50.5 mm.
5. After installing the valve guide, install the new valve and check for free sliding.