GM 90537666
Camshaft

The first step for exhaust camshaft and lifter replacement demands removal of the camshaft cover followed by the upper Timing Chain Guide. The camshaft sprocket holding tool (J 43655) should be installed next before removing both intake and exhaust camshaft sprocket bolts to discard them permanently. After moving the camshaft sprockets forward make bearing cap position marks to preserve original placement order. You should remove bearing caps and exhaust camshaft elements while moving the bolts one turn at a time until the camshaft loses its tension spring before proceeding with the hydraulic element lash adjusters and camshaft roller followers removal. When installing the valve tips should be lubricated before putting on the hydraulic element lash adjusters followed by camshaft roller followers to check that the alignment notches match with the camshaft sprocket. Place the exhaust camshaft and camshaft bearing caps on the engine block while tightening the bearing cap bolts three times until they reach seat position before final tightening to 10 nm (89 inch lbs.). After placing camshaft sprockets on camshafts apply finger tightness to new camshaft sprocket bolts and take away the camshaft sprocket holding tool (J 43655). The process ends with securing the upper Timing Chain Guide to 10 nm (89 inch lbs.) while the camshaft cover and camshaft sprocket bolts are finalized by a torque of 85 nm (63 ft. Lbs.) with an extra 30 degrees of rotation.

Begin exhaust camshaft and lash adjuster replacement operation by removing the exhaust camshaft position actuator. Detach each bearing cap bolt by turning it one revolution while marking the bearing caps for later use in proper reinstallation. The necessary steps start with bearing cap bolt extraction followed by bearing cap removal and exhaust camshaft extraction from the system. Separate all components of roller followers and hydraulic adjusters for reinstallation and afterward take out camshaft roller followers, hydraulic adjusters. Place the hydraulic element adjusters inside their bores in the Cylinder Head while applying gm pn 12345501 (Canadian PN 992704) or equivalent lubricant to both adjusters and valve tips. Used roller followers need to maintain their original position on the camshaft during installation. When the camshaft requires replacement it means you need to replace the associated roller followers which operate with it. Working with the same lubricating material transfer the roller followers onto the kale stem tip and lash adjuster. After lubricating the exhaust camshaft you should install it while tightening all bolts on the bearing caps by hand. To complete the repair stage you should first hand-tighten all bearing cap bolts before expanding the torque to 10 nm (89 inch lbs.) through alternating bolt movements of 3 turns. Reinstall the exhaust camshaft position actuator afterward.

Discard them afterward.

Lubricate the valve tips and install the hydraulic element lash adjusters and camshaft roller followers, ensuring the alignment notches are aligned with the camshaft sprocket.

Begin by removing the camshaft cover and the upper timing chain guide.