Unit Repair

DISASSEMBLE

CAUTION: Perform a compression test and note the results before removing the cylinder head(s) from the engine and before disassembling the valve mechanism. Keep the valve train components together and properly identified while disassembling the cylinder head.





1. Remove the spark plugs.





2. Use the Valve Spring Compressor in Order to compress the valve springs.

CAUTION: Avoid damaging the valve guide. If the valve stem has mushroomed or is burred in the key slot area, remove the burrs by chamfering the valve stem with an oil stone. Do not remove the valve from the guide with a hammer and punch.





3. Remove the valve locks.
4. Remove the valve caps.
5. Remove the valve stem oil seal.
6. Remove the valve springs.
7. Remove the valve spring shims, if equipped.
8. Remove the valves.





9. Remove the water jacket plugs.

ASSEMBLE
1. Lightly lap the reconditioned valves into the valve seat.
2. Install the cooling jacket plugs. Coat the jacket plugs with a GM P/N1050026 sealer or equivalent.

NOTE: Push the valve stem seals down as far as possible. Use an oversized valve stem if an oversized valve has been installed.

3. Install the valves
4. Measure the amount of valve runout. Do this by using the following method.
a. Lift the valve off of the valve seat
b. Apply a dab of Prussian blue to the valve face
c. Seat the valve
d. Carefully rotate the valve
e. Clean all traces of Prussian blue from the valve surfaces
f. Apply a dab of Prussian blue to the valve seat
g. Repeat the runout check
5. Recondition the valve sea/face or replace the valves if the Prussian blue is transferred to the valve.
6. Install the intake valve stem oil seals.
7. Install the spring shim, if required.
8. Install the valve stem O-ring.
9. Install the valve springs.
10. Install the valve caps.
11. Use Valve Spring Compressor in order to compress the valve springs.
12. Install the valve locks. Hold the valve locks in place with grease if necessary.
13. Release the valve springs.
14. Check to ensure that the valve locks are fully seated.

CAUTION: In order to avoid damage, install the spark plugs after the cylinder head has been installed on the engine.





15. Install the right cylinder head engine lift hook and bolts. Tighten the bolts to 50 Nm (37 ft. lbs.).