Removal from the Cylinder Head
1. Remove each valve from the head using a valve spring compressor. The compressor must act on the top cup to allow removal of the valve collets.
Valve removal
2. Once the collets are released, remove the following items:
- valve spring retainer
- valve spring
- valve spring base
- valve stem oil seal
- valve (de-burr before removal)
1. Valve stem seal
Note: Ensure inlet and exhaust valve components do not become mixed.
1. Collets; 2. Valve spring retainer; 3. Valve spring; 4. Valve spring base; S. Valve stem oil seal; 6. Valve
Installation
1. Lubricate the valve stems with a 50150 solution of engine oil and molybdenum disulphide grease.
2. Install the valve into the valve guide and refit the spring base to the valve spring recess in the head.
3. Fit the valve stem seal over the valve stem and, using a suitable tool, press down fully until the seal is correctly seated over the valve guide.
Note:
- During fitment of the valve stem seal, two distinctly different degrees of resistance will be noted when the seal is correctly fitted.
- Firsdy, press the seal down the valve stem until the lower side of the seal comes into contact with the valve guide. Greater resistance is felt at this contact point and further gentle pressure is then required to locate the seal over the top end of the valve guide.
- On application of this pressure, the seal can be felt to positively locate over the top face of the valve guide. Once correctly positioned, the seal cannot be pushed down any further.
Caution: Incorrect fitment of the valve stem oil seals could lead to high oil consumption and blue smoke emissions from the exhaust system. Do not use excessive force in fitting the seal as this may break the seal ring.
4. Install the valve spring over the valve stem. Ensure the close wound, colour coded ends of the springs are fitted downwards (towards the piston).
5. Fit the valve spring retainer.
6. Compress the valve spring ensuring that the spring is compressed squarely to prevent damage to the valve stem and cylinder head.
7. Fit the valve collets ensuring correct collet location in the spring retainer and valve as the spring compressor is released.
Caution: Always check for correct location of the valve collets during and after assembly. If not fitted correctly, the collets may become dislodged when the engine is running allowing the valves to contact the pistons. Any such valve to piston contact will cause severe engine damage.
Valve to Valve Guide Clearance
If the valve guides are worn beyond the service limit given below, the cylinder head must be replaced.
Valve Stem to Guide Clearance
- Inlet: 0.010 - 0.040 mm
- Service limit: 0.078 mm
- Exhaust: 0.030 - 0.060 mm
- Service limit: 0.098 mm
Valve Guides
If a valve guide is found to be worn beyond the service limit, the complete cylinder head must be renewed.
Valve Face Inspection
Remove any carbon build-up from the valve head area. Examine the valve seat face, checking in particular for signs of cracking or pitting.