- Clean the camshaft in solvent and allow it to dry.
- Inspect the camshaft for obvious signs of wear: scores, nicks, or pits on the journals or lobes. Light scuffs or nicks can be removed with oil stone.
- Using a micrometer, measure the diameter of the journals and compare to specifications. Replace the camshaft if any journals are not within specification.
- Measure the camshaft lobes at the major (A-A) and minor (B-B) diameters, using a micrometer. The difference in readings is the lobe height. Compare your measurements with the lobe height specifications. Replace the camshaft if any lobe heights are not within specification.
Inspect the camshaft and lifters/followers as described earlier in this section.Camshaft & Followers
Inspect the camshaft(s) and followers as described earlier in this section.Camshaft End Play
Remove the roller followers, as follows:
- Remove the valve cover(s).
- Position the piston of the cylinder being serviced at the bottom of the stroke and camshaft lobe at base circle.
Position the Valve Spring Compressor under the and on top of the valve spring retainer on the intake side.
Position the Valve Spring Compressor under the camshaft and on top of the valve spring retainer on the exhaust side.
- Remove the roller followers from the intake and exhaust sides.
- Compress the Valve Spring Compressor.
- Remove the roller followers. Repeat to remove all necessary roller followers.
- Use Special Tool Dial Indicator with Bracketry 100-002 (TOOL-4201-C) or equivalent to measure camshaft end play.
- Position the camshaft to the rear of the cylinder head.
- Zero the Dial Indicator with Bracketry.
- Move the camshaft to the front of the cylinder head. Note and record the camshaft end play. Proper specification range is 0.00098-0.00299 in. (0.025-0.076mm).
- If camshaft end play exceeds specifications, install a new camshaft and recheck end play.
If camshaft end play exceeds specifications after camshaft installation, install a new cylinder head.
Inspect camshaft lobes and the roller follower for pitting or damage in the active area. Minor pitting is acceptable outside the active area.
Removal & Installation
- Before servicing the vehicle, refer to the Precautions section.
- Remove the engine from the vehicle and mount it on a suitable workstand.
Remove or disconnect the following:
NOTEIf the rocker arms are to be reused, label them as they are removed so they can be reinstalled in their original locations.
Accessory drive belt and tensioner
- Install the camshafts and camshaft cap assemblies in their original positions.
- Tighten the camshaft cap assembly bolts in sequence as follows:
Install or connect the following:
Secondary chain tensioners
- Remove the engine from the workstand and install in the vehicle.
- Start the engine and check for leaks.
- Disconnect the negative battery cable.
- Properly relieve the fuel system pressure.
- Drain the cooling system and crankcase.
- Remove the engine from the vehicle and position in a suitable holding fixture.
- Remove the intake manifold.
- Remove the rocker arm covers, rocker arms, pushrods, and lifters.
- Remove the oil pan.
- Remove the front cover and timing chain.
- Remove the thrust plate. Remove the camshaft through the front of the engine, being careful not to damage bearing surfaces.
- Lightly oil all attaching bolts and studs threads before installation. Lubricate the cam lobes, thrust plate and bearing surfaces with suitable heavy engine oil.
- Install the camshaft being careful not to damage bearing surfaces while sliding into position. Install the thrust plate and tighten the bolts to 6-10 ft. lbs. (8-14 Nm).
- Install the front cover and timing chain.
- Install the oil pan.
- Install the lifters.
- Install the upper and lower intake manifolds.
- Install the engine assembly.
- Fill the cooling system and crankcase to the proper level and connect the negative battery cable.
- Start the engine. Check and adjust the ignition timing and engine idle speed as necessary. Check for leaks.
- Disconnect the negative battery cable and drain the cooling system. Relieve the fuel system pressure as described in Section 5.
- Remove the right and left valve covers.
- Remove the timing chain front cover. Remove the timing chains.
- Rotate the crankshaft counterclockwise 45 degrees from TDC to make sure all pistons are below the top of the engine block deck face.
- Install a valve spring compressor tool, under the camshaft and on top of the valve spring retainer.
- Compress the valve spring far enough to remove the roller follower. Repeat Steps 5 and 6 until all roller followers are removed.
- Remove the bolts retaining the camshaft cap cluster assemblies to the cylinder heads. Tap upward on the camshaft caps at points near the upper bearing halves and gradually lift the camshaft clusters from the cylinder heads.
- Remove the camshafts straight upward to avoid bearing damage.
- Apply heavy engine oil to the camshaft journals and lobes. Position the camshafts on the cylinder heads.
- Install and seat the camshaft cap cluster assemblies. Hand start the bolts.
- Tighten the camshaft cluster retaining bolts in sequence to 6.0-8.8 ft. lbs. (8-12 Nm).
- Loosen the camshaft cap cluster retaining bolts approximately 2 turns or until the heads of the bolts are free. Retighten all bolts, in sequence, to 6.0-8.8 ft. lbs. (8-12 Nm).
Check camshaft endplay as follows:
- Install a suitable dial indicator on the front of the engine. Position it so the indicator foot is resting on the camshaft sprocket bolt or the front of the camshaft.
- Push the camshaft toward the rear of the engine and zero the dial indicator.
- Pull the camshaft forward and release it. Compare the dial indicator reading with specification.
- If endplay is too tight, check for binding or foreign material in the camshaft thrust bearing. If endplay is excessive, check for worn camshaft thrust plate and replace the cylinder head, as required.
- Remove the dial indicator.
- If necessary, install the cam positioning tools, on the flats of the camshafts and install the spacers and camshaft sprockets. Install the bolts and washers and tighten to 81-95 ft. lbs. (110-130 Nm).
- Install a valve spring compressor, under the camshaft and on top of the valve spring retainer.
- Compress the valve spring far enough to install the roller followers.
- Repeat Steps 15 and 16 until all roller followers are installed.
- Rotate the crankshaft clockwise 45 degrees to position the crankshaft at TDC.
- Install the timing chains and install the timing chain front cover. Install the valve covers.