For 1990-2009 cars

### Removal Procedure

1. Partially drain the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
2. Remove the front ignition wire harness at the upper intake manifold and at the spark plugs.
3. Remove the thermostat bypass pipe. Refer to Thermostat Bypass Pipes Replacement in Engine Cooling.
4. Disconnect the positive crankcase ventilation (PCV) vacuum hose.

Notice: Valve rocker arm cover gasket and sealant must be carefully trimmed away from lower intake manifold gasket. Failure to do so will damage the lower intake manifold gasket, causing a severe oil leak.

5. Remove the valve rocker cover bolts.

Important: When removing the valve rocker arm cover, ensure the gasket stays in place attached to the cylinder head.

6. Remove the valve rocker cover.

Bump the end of the valve rocker cover with the palm of your hand or a soft rubber mallet if the cover adheres to the cylinder head.

7. Trim the valve cover gasket and sealant away from the lower intake manifold gasket at the cylinder head to lower intake manifold joints (1).
8. Remove the valve cover gasket.
9. Clean the sealing surface on the cylinder head with degreaser.
10. Clean the valve rocker arm cover. Refer to Valve Rocker Arm Cover Cleaning and Inspection .

### Installation Procedure

Important: All gasket mating surfaces need to be free of oil and foreign material. Use GM P/N 12346139 (Canadian P/N 10953463) or equivalent, to clean surfaces.

Important: Apply sealant GM P/N 12378521 (Canadian P/N 88901148), or equivalent at the cylinder head to lower intake manifold joint.

1. Apply sealant at the cylinder head to lower intake manifold joints (1).
2. Install a new gasket to the valve rocker cover. Ensure that the gasket is properly seated in the groove of the valve rocker arm cover.
3. Install the valve rocker cover.

Notice: Refer to Fastener Notice in the Preface section.

4. Install the valve rocker cover bolts.

Tighten
Tighten the bolts to 10 N·m (89 lb in).

5. Connect the PCV valve vacuum line.
6. Install the thermostat bypass pipe. Refer to Thermostat Bypass Pipes Replacement in Engine Cooling.
7. Install the front ignition wire harness.
8. Fill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.