Tools Required

1. Remove the left secondary camshaft drive chain tensioner. Refer to Secondary Camshaft Drive Chain Tensioner Replacement - Left Side .



2. Remove the intake camshaft sprocket bolt.



3. Remove the 2 chain guide access plugs (3, 4) located in the cylinder head. Note the O-ring seals on the access plugs.
4. Loosen the primary camshaft drive chain guide upper bolts ONLY 2 full turns.



5. Install the J 42042 on to the left cylinder head.
6. Slide the intake camshaft sprocket off of the camshaft and onto the pin of the J 42042 .
7. Secure the intake camshaft sprocket in place using a wire tie.




Important: DO NOT rotate the camshafts more than 10 degrees.

8. Remove the J 42038 .

Allow the camshaft lobes to find a neutral position by rotating each camshaft , if necessary.




9. Alternately loosen the camshaft bearing cap bolts a few turns at a time until all valve spring pressure has been released.
10. Remove the camshaft bearing caps.
11. Lift the left intake camshaft out of the cylinder head.
12. Remove the left secondary camshaft drive chain from the left intake camshaft sprocket.
13. Clean and inspect the camshaft timing drive components. Refer to Camshaft Timing Drive Components Cleaning and Inspection in Engine Mechanical-3.5L Unit Repair.

Important: Make sure the darkened chain links on the left secondary camshaft drive chain are facing inward.

1. Position the left secondary camshaft drive chain to the left intake camshaft sprocket.
2. Place the left intake camshaft (1) in position in the cylinder head.
3. Position the camshaft lobes in a neutral position with the front notch for the camshaft sprocket drive pins near the top of their rotation and the flats machined into the camshaft parallel and facing the cylinder head.



4. Observe the markings on the bearing caps. Each bearing cap is marked in order to identify its location. The markings have the following meanings:

•	The raised feature must always be oriented toward the outboard side of the engine.

•	The "I" indicates the intake camshaft.

•	The "E" indicates the exhaust camshaft.

•	The number indicates the journal position from the front of the engine.

5. Apply a liberal amount of lubricant GM P/N 12345501 or equivalent to the camshaft bearing caps.



6. Install the camshaft bearing cap bolts according to the identification marks.

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.

7. Tighten the camshaft bearing caps.

Tighten

1. Alternately hand tighten the camshaft bearing cap bolts a few turns at a time until all caps are fully seated.
2. Tighten the camshaft bearing cap bolts to 8 N·m (71 lb in).
3. Tighten the camshaft bearing cap bolts an additional 22 degrees using the J 36660-A .




Caution: The camshaft holding tools must be installed on the camshafts to prevent camshaft rotation. When performing service to the valve train and/or timing components, valve spring pressure can cause the camshafts to rotate unexpectedly and can cause personal injury.

Important: There should be no need to rotate the camshaft more then 10 degrees.

8. Using the hex cast into the camshaft, rotate the camshaft so the rear camshaft flat is facing the cylinder head in order to install the J 42038
9. Install the J 42038 to the rear of the camshafts on the left cylinder head.



10. Slide the intake camshaft sprocket off of the J 42042 and onto the camshaft, aligning the drive pin into the camshaft notch.
11. Remove the J 42042 from the left cylinder head.
12. Tighten the primary camshaft drive chain guide upper bolts.

Tighten
Tighten the primary camshaft drive chain guide bolts to 25 N·m (18 lb ft).





Important: Ensure that each chain guide access plug has an O-ring installed.

13. Install the 2 chain guide access plugs (3, 4).

Tighten
Tighten the chain guide access plugs to 5 N·m (44 lb in).




14. Install the intake camshaft sprocket bolt.

Tighten

1. Tighten the camshaft sprocket bolt to 25 N·m (18 lb ft).
2. Use the J 36660-A in order to tighten the camshaft sprocket bolt an additional 45 degrees.
15. Install the left secondary camshaft drive chain tensioner. Refer to Secondary Camshaft Drive Chain Tensioner Replacement - Left Side .