Tools Required

Important: 

•	Any time the camshaft housing to the cylinder head bolts are loosened or removed, the camshaft housing to the cylinder head gasket must be replaced.

•	During disassembly, ensure that the valve lifters are kept together and identified so that they can be reinstalled in the original locations.

•	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.

1. Disconnect the negative battery cable.
2. Remove the ignition coil and the module assembly electrical connections.
3. Remove the ignition coil and the module assembly to the camshaft housing bolts.



4. Remove the assembly by pulling straight up.
5. Remove the camshaft position sensor connector.



6. Remove the power steering pump and position aside.

Do not disconnect the power steering lines.

7. Remove the vacuum line from the fuel pressure regulator and the fuel injector harness connector.
8. Remove the fuel line retaining clamp from the bracket on top of the intake camshaft housing.



9. Remove the fuel rail to the camshaft housing retaining bolts.
10. Remove the fuel rail from the cylinder head as follows:

•	Cover the injector openings in the cylinder head.

•	Cover the injector nozzles.

•	Leave the fuel lines attached and the position fuel rail aside (on top of the master cylinder).

11. Disconnect, but do not remove from the vehicle, the timing chain housing at the intake camshaft housing. Refer to Timing Chain Housing Replacement .



12. Remove the camshaft housing cover to the camshaft housing retaining bolts.




Important: 

•	Use the reverse of the tightening procedure when loosening the camshaft housing to the cylinder head retaining bolts.

•	Leave the two bolts loosely in place in order to hold the camshaft housing while separating the camshaft cover from the housing.

13. Remove the camshaft housing to the cylinder head retaining bolts i the sequence shown.

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

14. Push the cover off the housing by threading four of the housing to head retaining bolts into the tapped holes in the camshaft housing cover.
15. Remove the two loosely installed camshaft housing to head bolts.
16. Remove the cover and discard the gaskets.
17. Loosely reinstall one camshaft housing to cylinder head bolt in order to retain the housing during the camshaft and lifter removal.
18. Note the position of the chain sprocket dowel pin for reassembly.

Remove the camshaft being careful not to damage the camshaft or the journals.

Important: The valve lifters are not serviceable. Replace faulty valve lifters.

Coat the valve lifter with the Camshaft and Lifter Prelube GM P/N 12345501 or the equivalent. If the new lifters are installed, add the Engine Oil Supplement GM P/N 1052367, or the equivalent, to the engine oil.
19. Remove the valve lifters as follows:

•	Keep the lifters in order to reinstall the lifters to the original locations.

•	In order to minimize the lifter bleed down, perform the following procedure:

-	Store the lifters upside down, opposite of the installed position, on a level surface.

-	Store the lifters submerged in clean engine oil.





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

20. Remove the camshaft housing and the gasket.

Important: Do not attempt to repair the camshaft, replace if damaged.

If a new camshaft is installed, all of the valve lifters actuated by the camshaft must also be replaced.
21. Inspect the following camshaft components for damage:

•	The sprocket

•	The keyway and the threads

•	The camshaft position sensor reluctor

22. Inspect the camshaft bearing surfaces and the camshaft lobes for the following damage:

•

Wear

•

Galling

•

Gouges

•	Overheating or discoloration

Important: 

•	If a new camshaft has been installed, add the Engine Oil Supplement GM P/N 1052367 or the equivalent to the engine oil.

•	Coat the entire camshaft with the Camshaft and Lifter Prelube GM P/N 12345501 or the equivalent.

23. Measure the bearing journals diameter with a micrometer.

If out of specification, replace the camshaft.

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

Sealer is unnecessary.

2. Loosely install on camshaft housing to the cylinder head bolt in order to hold the housing in place.

Important: Used lifters must be returned to the original position in the camshaft housing. If the camshaft is being replaced, the lifters actuated by the camshaft must also be replaced.

3. Install the lifters into the lifter bores.
4. Install the camshaft in the same position as when removed.

The timing chain sprocket dowel pin should be straight up and line up with the centerline of the lifter bores.

5. Install the new camshaft housing to the green colored camshaft housing cover seals and into the cover.

Sealant is unnecessary.

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



8. Install the camshaft housing cover to the camshaft housing.




Important: The top intake camshaft housing bolts are tightened to a different specification than the other camshaft housing bolts.

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.

9. Using the J 36660-A

Tighten

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

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

10. Rotate the bolts the amount of degrees specified in sequence.
11. Install the timing chain housing and the timing chain. Refer to Timing Chain Housing Replacement .
12. Uncover the fuel injectors and install the new injector O-ring seals.

Lubricate the O-ring seals with engine oil.




13. Uncover the injector openings in the cylinder head and install the fuel rail onto the cylinder head.
14. Install the fuel rail to the camshaft housing bolts.

Tighten
Tighten the camshaft housing bolts to 26 N·m (19 lb ft).

15. Install the fuel line retaining clamp and the retainer to the bracket on top of the camshaft housing.
16. Install the vacuum line to the fuel pressure regulator.
17. Install the fuel injector harness connector.
18. Install the camshaft position sensor connector.




Important: When reinstalling the power steering pump, apply a 3 mm bead of GM P/N 12346286 sealer or the equivalent to the joint at the end of the camshaft housing halves before the installation of the power steering pump and the pump face seal.

19. Install the power steering pump assembly.
20. Reinstall any spark plug boot connector assembly that has stuck to a spark plug back onto the ignition coil and module assembly.
21. Locate the ignition coil and the module assembly over the spark plugs and push straight down.
22. Clean any loose lubricant that is present on the ignition coil and the module assembly to the camshaft housing bolts.
23. Apply pipe sealant GM P/N 1052080 or the equivalent onto the ignition coil and the module cover assembly to the camshaft housing bolts.

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

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.

24. If new lifters have been installed or the lifters bled down while the engine was disassembled, excessive lifter noise may be experienced. This is a normal condition and no engine damage is occurring. Use the following procedure to purge air from the lifters:

24.1.

Start the engine and allow the engine to warm up at idle for 5 minutes.

24.2.

Increase the engine speed to 2,000 RPM until the lifter noise is gone.

24.3.

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

25. Install the electrical connector to the ignition coil and the module assembly.

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.

26. Connect the negative battery cable.

Tighten
Tighten the bolt to 16 N·m (12 lb ft).