51. Intake Camshaft and Valve Lifter Installation

Important:
^ Do not turn the camshafts or start the engine for approximately 30 minutes after replacing the valve lifters and camshafts.
^ Allow approximately 30 minutes for the valves to settle in place. Operating the valves before this time may cause valve or piston damage.
^ The valves may make a tapping/ticking sound after replacement if air is trapped in the valve lifter. Run the engine at 2000 RPM until the air is purged from the lifter.
^ If the tapping/ticking does not stop, locate the defective lifter with a stethoscope and replace. Or, remove the cylinder head cover with the engine stopped and push the lifter down by hand with a force less than 20 kg (44 lbs.) when the camshaft is on the base circle. If clearance exists between the camshaft and the lifter, the lifter is faulty and should be replaced.

1. Pour engine oil into the oil feed hole in the valve lifter bore in order to flush any debris from the gallery and to prelube the bore.
2. Apply engine oil to the valve lifter and install the lifter to the cylinder head in the same bore from which it was removed.
3. Line up the crankshaft keyway with the timing mark on the engine block.
4. Rotate the crankshaft 90 degrees clockwise in order to prevent interference between the valves and the pistons.
5. Apply engine oil to the camshaft journals and lobes.





6. Install the camshaft aligning the guide pins (1) with the notches (3) on the cylinder head. The exhaust camshaft rear end is slotted to mate with the camshaft position sensor.





7. Install the dowel pins (1) to the cylinder head.
8. Apply a bead of GM P/N 12345997 or equivalent to the exhaust camshaft end housing (2).





Important: Cylinder head and camshaft damage may result if the bearing caps are incorrectly installed.

9. Install the camshaft bearing caps. The caps are marked intake or exhaust (1), position away from the timing chain (2), and direction toward the timing chain (3).





Notice: Refer to Fastener Notice in Service Precautions.

10. Tighten the camshaft bearing caps.
Tighten the camshaft bearing caps in 3 progressive steps in the sequence shown to 11 Nm (97 inch lbs.).