Unit Repair

TOOL REQUIRED
^ J 38606 Valve Spring Compresssor

NOTE: Perform a compression test before removing the cylinder head from the engine. Note the results of the compression test.

CAUTION: Ensure that the valve train components are kept together when disassembling the cylinder head. Identify the valve train components. The valve train components must be installed in the original location.

DISASSEMBLE
1. Remove the spark plugs.





2. Remove the left cylinder head engine lift hook bolts.
3. Remove the engine lift hook.





4. Remove the fuel line bracket bolts.
5. Remove the fuel line bracket.
6. Remove the engine coolant temperature sensor.

CAUTION: Do not damage the valve guide. Remove any burrs that have formed at the key groove by chamfering the valve stem with an oil stone or a file.





7. Compress the valve springs. Use the Valve Spring Compressor.





8. Remove the valve spring cap keys.
9. Remove the valve spring caps.
10. Remove the valve springs.
11. Remove the valves.
12. Remove the valve stem oil seals.
13. Remove the spring seats.
14. Remove the coolant jacket plugs.

ASSEMBLE

CAUTION: Use oversize valve stem seals if you install oversize valves.

1. Lightly lap the reconditioned valves into the valve seat.
2. Coat the coolant jacket plugs with sealer. Use GM P/N 1050026 or its equivalent.
3. Install the coolant jacket plugs. Tighten the plugs to 19 Nm (14 lb ft).
4. Install the valve stem oil seals.
5. Install the valves.
6. Use the following procedure to measure the valve seat concentricity:
a. Lift the valve off its seat.
b. Apply a dab of Prussian blue to the valve face.
c. Seat and rotate the valve. The Prussian blue traces transferred to the valve seat are an indication of concentricity of the valve seat.
7. Use the following procedure to measure valve runout:
a. Clean all traces of the Prussian blue from the valve face and the valve seat.
b. Apply a dab of Prussian blue to the valve seat.
c. Seat and rotate the valve. The traces of Prussian blue transferred to the valve indicates valve runout.
d. Recondition the valve seat or valve face if needed. Replace the valves if necessary.
8. Install the valve springs.
9. Install the valve spring caps.
10. Compress the valve springs. Use the Valve Spring Compressor.
11. Install the valve spring cap keys. Hold the valves in place with grease, if necessary.
12. Release the valve springs.
13. Make sure valve locks are seated.
14. Install the engine coolant temperature sensor.
15. Install the fuel line bracket.
16. Install the fuel line bracket bolts.

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

17. Install the engine lift hook.
18. Install the left cylinder head engine lift hook bolts.