REMOVAL & INSTALLATION
See Figure 1
The cylinder heads must be removed from the engine to remove the camshafts.
- Remove the timing belt.
- Drain the coolant by removing drain plug on the cylinder block.
- Remove the intake manifold assembly.
- Remove the cylinder head from the engine.
- With cylinder head mounted on a suitable workbench, remove the rocker shafts with rocker arms. Bolts should be loosened in 2-3 steps.
- Remove the hydraulic lash adjusters and guide.
Hold hydraulic lash adjusters with wire so they will not drop from the guide.
- Remove the camshaft front oil seal and slide camshaft out of the cylinder head.
- Install camshaft, locate plate, cylinder head rear cover and front oil seal. Set camshaft knock pin at 12 o'clock position.
- Install the cylinder head(s).
- Install valve adjuster guide assembly. Assemble the hydraulic adjusters in their original position. After installing them in the correct location remove the wire holding them in the guide.
Install the rocker shafts in correct position with the rocker arms. Tighten bolts in 2 -3 stages to 13-16 ft. lbs. Before tightening, be sure to set camshaft lobe at the position where lobe is not lifted or the valve closed. You can set each cylinder one at a time or follow the procedure below (timing belt must be installed in the correct position):
- Set No. 1 piston at TDC on its compression stroke and tighten rocker shaft bolts for No. 2, No. 4 and No. 6 cylinders.
- Set No. 4 piston at TDC on its compression stroke and tighten rocker shaft bolts for No. 1, No. 3 and No. 5 cylinders.
- Torque specification for the rocker shaft retaining bolts is 13-16 ft. lbs.
- Install the intake manifold and collector assembly.
- Install rear timing belt cover and camshaft sprocket. The left and right camshaft sprockets are different parts. Install the correct sprocket in the correct position.
- Install the timing belt.
See Figures 2 through 15
The upper timing chains must be removed to allow for camshaft removal. Refer to the Timing Chain procedure in this section.
- Remove the valve cover. If removing the rear camshaft, the intake manifold collector must be removed.
- Remove the upper timing chain cover(s) on the front of the cylinder head(s).
- Set the engine to TDC on the number one cylinder on the compression stroke.
- Mark the timing chain and sprockets for proper alignment during installations.
- Remove the timing chain tensioners and upper chain guides.
- Using a back-up wrench on the camshafts, remove the camshaft sprocket bolts and the sprockets.
- Loosen the camshaft brackets in numerical order as shown in the illustration. Be sure not to mix up the camshaft brackets.
- Lift the camshaft(s) from the cylinder heads.
- The rocker arms and hydraulic lash adjusters can be removed after the camshafts are removed.
Do not lay the lifters on their sides; there is a chance of air entering them. Keep them upright, or store them in clean engine oil. Be sure to keep them in the order they were removed from the cylinder heads.
- Using engine assembly lubricant, lightly coat the bearing surfaces of each of the camshafts.
- Install the camshaft brackets. Tighten the brackets in numerical order as shown in the illustrations.
- Using a back-up wrench on the camshafts, install the camshaft sprocket bolts and the sprockets. Dip the sprocket bolts in fresh engine oil and torque the bolts to 80-87 ft.lbs. (108-118 Nm.).
- Install the timing chain tensioners and upper chain guides.
- Install the upper timing chain cover(s) on the front of the cylinder head(s).
- Install the valve cover(s). If the camshafts on the rear cylinder head were removed, install the intake manifold collector.
See Figures 16 through 20
The front and rear timing chain cover and timing chains must be removed to allow for camshaft removal. Refer to the Timing Chain procedure in this section.
- Remove the rear timing chain case bolts.
- Remove the rear timing chain case from the engine block.
- Loosen the intake and exhaust camshaft brackets, in several steps as shown in the illustrations. Be sure to mark the positions of the camshaft brackets prior to removal.
- Remove the camshafts from the cylinder heads.
- Remove the bucket-type cam followers from the cylinder heads. Be sure not to mix up the shims. Use egg cartons or other means to keep the followers and shims in the proper order. All camshaft components should always be installed in their original locations.
- Using engine assembly lubricant, lightly coat the followers with engine oil and install them into the cylinder heads.
- Using engine assembly lubricant, lightly coat the bearing surfaces and the cam lobes.
- Install the camshafts to the cylinder heads. Position the dowel pins as shown in the illustration.
- Tighten the camshaft brackets in three stages:
- Clean the mating surfaces of the rear timing chain cover and the cylinder block.
- Install new O-rings to the cylinder block.
- Apply a bead of liquid gasket to the mating surface of the timing chain case.
- Mount the rear timing chain case to the engine block. Torque the bolts to 8.7-10.1 ft.lbs. (11.8-13.7 Nm.) in numerical order as shown in the illustration.
- Install the timing chain.
See Figures 21 through 26
- Visually check the camshaft for scratches, seizures and/or wear; if necessary, replace the camshaft.
Refer to the Engine Specifications Chart for measurements and specifications.
- To check the camshaft runout, position camshaft in a set of "V" blocks.
- Mount a dial indicator so it contacts the camshaft at a 90° angle to the bearing surfaces.
- Rotate the camshaft to measure the cam bearing journal runout.
- To check the camshaft lobe height, use a micrometer to check cam (lobe) height, making sure the anvil and the spindle of the micrometer are positioned directly on the heel and tip of the cam lobe.
- To check the camshaft journals, measure them with a micrometer.
- Install the camshaft brackets and torque them to the specified torque.
- Using an internal micrometer, measure the cylinder head camshaft bearing journals.
- If the measurements are less than the limits listed, the camshaft will have to be replaced, since the camshafts in all of the engines covered in this guide run directly on the cylinder head surface; no actual bearings or bushings are used, so no oversize bearings or bushings are available.
To check the camshaft end play, perform the following procedures:
- Install the camshaft into the cylinder head.
- Using a dial micrometer, mount it at a 90° angle to the end of the camshaft. Move the camshaft in and out, then, measure the end play. Refer to the Engine Specifications Chart.
- If the end play is out of range, install another locate plate to bring the tolerance within specifications.
See Figures 27 through 28
- Visually inspect the contact and sliding areas of the follower. Replace as necessary.
- Using a micrometer, measure the diameter of the follower.
- Using an internal micrometer, measure the follower bore in the cylinder head. Refer to the Engine Specifications Chart for specifications.