48. Cylinder Head Assemble

- Tools Required
- J8062 Valve Spring Compressor
- J42078 Valve Stem Oil Seal Installer





1. Clean the cylinder head valve spring shim area.

Important: When reusing the valves and related components, install the parts to their original location.

2. Install the valves (10 and 12) into the proper port.
3. Install the valve spring shim (6).

Important: The valve stem oil seal alignment and position on the valve guide is critical. An improperly installed valve stem oil seal may lead to excessive oil consumption, increased vehicle emissions, or component damage.





4. Install the valve stem oil seal (5) onto the guide (7).
4.1. Lubricate the valve guide (7) and valve stem (5) oil seal with clean engine oil.
4.2. Install the valve stem oil seal onto the valve stem. Push the seal down until the seal contacts the valve guide.
4.3. Use the J42078 in order to install the valve stem oil seal.
Push or lightly tap the tool until the tool bottoms against the valve spring shim (6).





5. Measure the valve stem oil seal for the properly installed height.
There should be a 18.1 - 19.1 mm (0.712 - 0.752 inch) gap between the top edge of the oil seal body and the valve spring shim surface.





6. Install the valve spring (4).
7. Install the valve spring cap (3).





8. Compress the valve spring (4) using the J8062.
9. Install the valve stem keys (2).
9.1. Use grease to hold the keys (2) in place and remove the J8062.
9.2. Make sure the keys (2) seat properly in the groove of the valve stem (10 and 12).
9.3. Tap the end to the valve stem (10 and 12) with a plastic faced hammer to seat the keys (if necessary).





10. Measure the valve spring installed height using a ruler.
Measure from the base of the valve spring to the top of the valve spring.
- If the installed height exceeds 46.25 mm (1.82 inch), install a valve spring shim of approximately 0.5 mm (0.02 inch) thick.
- Do not shim the valve spring to obtain less than the specified height.
Do not assemble the components without a spring shim on the cylinder head.
11. Install the remaining valves (10 and 12), springs (4) and other components.





12. Install sealant GM P/N 12346004 or equivalent to the threads of the coolant sensor.

Notice: Refer to Fastener Notice in Service Precautions.

13. Install the coolant sensor into the left cylinder head (if required).
- Tighten the coolant sensor to 20 Nm (15 ft. lbs.).





14. Install the coolant plug to the right cylinder head.
- Tighten the coolant plug to 20 Nm (15 ft. lbs.).
15. Install sealant GM P/N 12345382 or equivalent to the cylinder head core plug holes.
16. Install NEW cylinder head core plugs (if required).





17. Apply threadlock GM P/N 12345382, or equivalent, to the sides of the cylinder head expansion plugs (1).
18. Install the expansion plugs into the cylinder head. A properly installed plug should be slightly below flush with the face of the head.