For 1990-2009 cars

### Removal Procedure

Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

1. Disconnect the negative battery cable.
2. Remove the Valve Rocker Arm Cover. Refer to Valve Rocker Arm Cover Replacement in Engine Mechanical.
3. Remove the timing belt. Refer to Timing Belt Replacement in Engine Mechanical.
4. Remove the camshaft. Refer to Camshaft Replacement in Engine Mechanical.

Important:

• | Never disassemble the Hydraulic Valve Lash (HVL) adjuster.

• | Do not apply force to the body of the adjuster or the oil in the high pressure chamber.

• | Submerge the removed adjusters in clean engine oil until reinstallation. If the adjusters are left in the air, place with the adjuster bodies facing down. Do not place on the side or with the adjuster bodies facing up.

5. Remove the six Hydraulic Valve Lash (HVL) Adjusters (1) from the cylinder head.

### Installation Procedure

1. Pour engine oil through the camshaft journal holes (2).
2. Inspect that the engine oil comes out from the oil holes in the HVL adjuster bores.
3. Apply engine oil around the HVL adjuster.
4. Install the HVL adjuster (1) to the cylinder head.
5. Apply engine oil to the camshaft journal and around all of the cams.
6. Install the camshaft into the cylinder head so that the camshaft timing gear pin hole (1) in the camshaft is at the lower position.
7. Apply engine oil to the sliding surface of each housing against the camshaft journal.
8. Apply GM P/N 12346240 or equivalent, to the mating surface of the No. 1 and No. 3 housings (1) which will mate with the cylinder head.

Important: The camshaft housing No. 1 retains the camshaft in the proper position as to the thrust direction. Install the housing No. 1 to the journal No. 1 first. Do not tighten fully.

9. Install the camshaft housing No.1 (1) to the camshaft and the cylinder head with the arrow on the camshaft housing (2) facing the timing belt side.

Important: Apply a light amount of engine oil to the housing bolts before securing the camshaft housings to the camshaft journals.

10. Install the two remaining camshaft housings (2, 3) to the journals of the camshaft.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

11. Secure the camshaft housings with the housing bolts.

Tighten
Tighten the bolts a little at a time and evenly among the bolts. Repeat the tightening process three or four times until they are tightened to 11 N·m (97 lb in).

12. Apply engine oil to the camshaft oil seal lip.
13. Press-fit the camshaft oil seal until the oil seal surface becomes flush with the housing surface.
14. Install the camshaft. Refer to Camshaft Replacement in Engine Mechanical.
15. Install the timing belt. Refer to Timing Belt Replacement in Engine Mechanical.
16. Install the Valve Rocker Arm Cover. Refer to Valve Rocker Arm Cover Replacement in Engine Mechanical.