Valve Spring Lock: Service and Repair

DISASSEMBLY
1. Remove cylinder head bolts.





2. With cylinder head removed, compress valve springs using Special Tool MD998772A and 6779, or equivalent.
3. Remove valve retaining locks, valve spring retainers and valve spring.





4. Remove valve stem seal/valve spring seat by using Special Tool C-4745 or equivalent.
5. Before removing valves, remove any burrs from valve stem lock grooves to prevent damage to the valve guides. Identify valves to insure installation in original location.

CLEANING

CAUTION: Be careful not to gouge or scratch the aluminum head sealing surface.

Cylinder Head
Remove all gasket material from cylinder head and block.

Valve Assembly
Clean all valve guides, valves and valve spring assemblies thoroughly with suitable cleaning solution before reassembling.

ASSEMBLY
1. Coat valve stems with clean engine oil and insert them in cylinder head.
2. If valves or seats have been reground, check valve tip height. Make sure measurements from cylinder head surface to the top of valve stem.





3. Install valve seal/spring seat assembly over valve guides on all valve stems. Ensure that the garter spring is intact around the top of the rubber seal. Install valve springs, valve retainers.
4. Compress valve springs with a valve spring compressor install locks and release tool.


5. Cylinder head bolts should be carefully examined before reuse. If the threads are necked down, the bolts should be replaced.





NOTE: Necking can be checked by holding a scale or straight edge against the threads. If all the threads do not contact the scale, the bolt should be replaced.

6. Before installing the bolts, the threads should be oiled with clean engine oil.





7. Tighten the cylinder head bolts in the sequence shown in the illustration. Using the 4 step torque turn method, tighten according to the following values.
a. Tighten center fasteners 1 thru 6 to 33 Nm (25 ft. lbs.). Then outer fasteners 7 thru 10 to 27 Nm (20 ft. lbs.).
b. Tighten center fasteners 1 thru 6 to 67 Nm (50 ft. lbs.). Then outer fasteners 7 thru 10 to 27 Nm (20 ft. lbs.).
c. Tighten center fasteners 1 thru 6 to 67 Nm (50 ft. lbs.). Then outer fasteners 7 thru 10 to 27 Nm (20 ft. lbs.).

CAUTION:
1. Always make a tightening angle just 90°. If it is less than 90°, the head bolt will be loosened.
2. If it is more than 90°, remove the head bolt and repeat the procedure from step 1.





d. Turn all fasteners 1 thru 10 90° turn. Do not use a torque wrench for this step.