The lobe lift may be checked without removing the camshaft, simply remove the valve cover and rotate the engine while observing each rocker assembly. There should be a substantial and consistent amount of lift between all rockers. If a camshaft lobe is excessively worn there is usually some rocker arm play and valve noise during engine operation.
If the camshaft is suspected of excessive wear, removal will be necessary for a more thorough examination. Once removed, the camshaft lobes should be examined for wear or pitting. The camshaft journals and bearings should also be inspected for wear and pitting. The journals can be measured using a micrometer and then compared to factory specifications.
Removal & Installation
Before servicing the vehicle, refer to the Precautions Section.
NOTEDisconnecting the negative battery cable on some vehicles may interfere with the functions of the on-board computer systems and may require the computer to undergo a relearning process, once the negative battery cable is reconnected.
NOTEIf working near and/or around the SRS system and components, be sure to properly disable the SRS system. See disarming/arming the SRS system.
- Disconnect the negative battery cable.
Remove the intake manifold.
- Remove the rocker arm assemblies and pushrods.
- Loosen the belt tensioner and remove the serpentine belt.
- Remove the upper fan shroud, radiator hoses, oil cooler lines and the radiator.
- Remove the timing chain.
- Properly discharge the air conditioning, disconnect and remove the condenser.
- Remove the valve lifters.
- Remove the camshaft retainer bolts and the camshaft retainer.
- Install three 4 inch long bolts in the camshaft bolt holes and carefully pull camshaft from bearings.
- Coat camshaft lobes and journals with prelube 1052365 or equivalent.
- Carefully slide camshaft into the block.
- Install the camshaft retainer and retainer bolts. Tighten bolts to 106 inch lbs. (12 Nm).
- Install the timing chain.
- Install new valve lifters to assure durability of the camshaft lobes and lifter rollers.
- Install the air conditioning condenser.
- Install the radiator, oil cooler lines and radiator hoses.
- Install the serpentine drive belt.
- Install the upper fan shroud.
- Install the pushrods and rocker arm assemblies
- Install the intake manifold.
- Connect the negative battery, change the oil and filter, add coolant, and adjust valves.
- Using the GM diagnostic scan tool or aftermarket equivalent reprogram the necessary systems and components. Be sure to follow the scan tool manufacturer-s directions.