Tools Required

Important: If you loosen or remove the bolts which secure the camshaft housing to the cylinder head, replace the gasket between the camshaft housing and the cylinder head. During disassembly, keep the valve lifters together and identified, so that you can reinstall the lifters in the original locations.

1. Before disassembling the valve mechanism, make a compression test and note the results. Refer to Engine Compression Test .

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.

2. Disconnect the negative battery cable.
3. Disconnect the ignition coil and the module assembly electrical connection.



4. Remove the ignition coil bolts. Remove the bolts securing the module assembly to the camshaft housing.
5. Remove the assembly by pulling straight up.
6. The connector assembly may be stuck to the spark plugs. Use J 36011 by first twisting then pulling upward on the connector assembly.
7. Disconnect the electrical connection from the oil pressure switch.
8. Disconnect the timing chain housing at the exhaust camshaft housing, but do NOT remove the parts from the vehicle. Refer to Timing Chain Housing Replacement .



9. Remove the exhaust camshaft cover and the gasket.



10. Remove the bolts which secure the exhaust camshaft housing to the cylinder head.



11. Use the reverse of the tightening procedure when loosening the retaining bolts which secure the camshaft housing to the cylinder head.
12. Leave 2 bolts loosely in place in order to hold the camshaft housing while you separate the camshaft cover from the housing.
13. Push the cover off the housing by threading 4 retaining bolts, which secure the housing to the head, into the tapped holes in the camshaft cover.

Important: Tighten the bolts evenly in order to prevent the cover from binding on the dowel pins.

14. Remove the 2 loosely-installed bolts which secure the camshaft housing to the head.



15. Remove the cover.
16. Discard the gaskets.
17. Loosely reinstall 1 bolt in order to retain the camshaft housing to the cylinder head during removal of the camshaft and the lifter.



18. Notice the position of the chain sprocket dowel pin for reassembly. Remove the camshaft carefully in order to prevent damage to the camshaft or the journals.



19. Remove the valve lifters.

Keep the lifters in order so that you can reinstall the lifter in the original location.

Important: 

•	Replace any faulty lifters.

•	If you install new lifters, add the Engine Oil Supplement GM P/N 1052367 or the equivalent to the engine oil.

20. In order to minimize lifter bleed down, use the following procedure:

•	Store lifters upside down on a level surface (place the camshaft contact surface down).

•	Store the lifters submerged in clean engine oil.

Important: Ensure that the camshaft housing alignment dowel pins are in the cylinder head prior to installing the housing.




21. Remove the camshaft housing gasket.

1. Install the camshaft housing to the cylinder head with a new gasket.

Sealer is unnecessary.

2. Loosely install 1 bolt, which secures the camshaft housing to the cylinder head, in order to hold the housing in place.




Important: 

•	Return used lifters to their original position in the camshaft housing.

•	If you replace the camshaft, replace the lifters also.

3. Install the lifters into the lifter bores.

Notice: The camshaft lobes and the journals must be adequately lubricated or serious engine damage will occur upon start up.

4. Lube the camshaft lobes and the journals with the Camshaft and Lifter Prelube GM P/N 12345501 or the equivalent.



5. Install the camshaft in the same position as removed.



6. Set the timing chain sprocket dowel pin straight up, and align the pin with the centerline of the lifter bores.



7. Install the new seals between the camshaft housing and the orange camshaft housing cover.

Sealer is unnecessary.

8. Remove the bolt holding the housing in place.
9. Apply pipe sealant GM P/N 1052080 or the equivalent to the camshaft housing and to the threads of the cover retaining bolt.



10. Install the cover to the camshaft housing.

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. Use the J 36660-A in order to install the bolts.

Tighten

•	Tighten the bolts which secure the camshaft housing to the cylinder head to 15 N·m (11 lb ft) + 90 degrees.

•	Tighten the bolts which secure the camshaft housing cover to the camshaft housing to 15 N·m (11 lb ft) + 30 degrees.

12. Install the timing chain housing to the camshaft housing and the timing chain. Refer to Timing Chain Housing Replacement .
13. Install the exhaust camshaft housing cover and the new gasket.
14. Connect the electrical connection to the oil pressure switch.
15. If any spark plug boot connector assembly is stuck to a spark plug, reinstall the connector onto the ignition coil and the module assembly.



16. Locate the ignition coil and the module assembly over the spark plugs.
17. Push straight down.
18. Clean any lubricant from the ignition coil and the bolts which secure the module assembly to the camshaft housing.
19. Apply pipe sealant GM P/N 1052080 or the equivalent onto the ignition coil and onto the bolts which secure the module assembly to the camshaft housing.

Tighten
Tighten the bolts to 15 N·m (11 lb ft) + 30 degrees.

20. Connect the electrical connector to the ignition coil and to the module assembly.
21. Connect the negative battery cable.

Important: Do not compress the lifter plungers using a vise or other tool. This will cause more air to enter the lifter assembly and will take more time to bleed out once the lifters are installed.

22. If you have installed new lifter or if the lifters bled down while the engine was disassembled, you may experience excessive lifter noise. This is a normal condition and no engine damage is occurring. Use the following procedure in order to purge the air from the lifters:

22.1.

Start the engine and warm the engine at the idle for 5 minutes.

22.2.

Increase the engine speed to 2000 RPM until the lifter noise is gone.

22.3.

Return the engine to idle for an additional 5 minutes or perform a road test.

23. Start the engine. Inspect for leaks.