REMOVAL & INSTALLATION
See Figures 1 through 10
- Disconnect the negative battery cable.
- Remove the valve cover.
- Remove the camshaft timing belt and sprockets.
Mark the camshaft journal caps to the cylinder head for installation. Do not mix the caps between the two camshafts or from another cylinder head.
- Loosen all of the camshaft journal cap bolts in pairs and in sequence one turn at a time starting at the rear cap. This will allow the camshaft to raise up from the cylinder head evenly.
Remove the camshaft journal thrust caps last.
- Remove all of the camshaft journal caps making sure that they are marked so that they can be reassembled to their original positions.
- Remove the intake and exhaust camshafts and the camshaft front seals from the cylinder head.
- Inspect the camshafts and cylinder head for wear.
If the valve lifters (tappets) are to be reused, mark their locations to ensure that they will be installed into their correct positions.
- If required, remove the valve lifters from the cylinder head.
- Inspect the valve lifters for wear.
Before installing the camshafts, the crankshaft must be positioned so that No. 1 cylinder is at TDC on its compression stroke.
- If removed, lubricate the valve lifters with engine assembly lubricant and install into the lifter bores that they were removed from.
- If the valve lifters are new, soak the lifters in a container of clean engine oil or manually pump up the lifters before installation.
- Lubricate the camshafts with engine assembly lubricant and place the camshafts into the cylinder head.
The intake and exhaust camshafts are marked for identification, also the intake camshaft has an extra cam lobe for the Camshaft Position (CMP) sensor.
- Loosely install the camshaft journal caps and retaining bolts into their original positions.
- Install the camshaft journal thrust caps and retaining bolts last. Apply a bead of silicone sealant to the sealing surfaces of the camshaft journal thrust caps.
- Tighten all of the camshaft journal caps in several steps pulling the camshaft down evenly following the proper sequence.
- Once the camshaft journal caps are fully seated, tighten the retaining bolts to 13-15 ft. lbs. (17-21 Nm).
- Install new camshaft front seals using the an appropriate camshaft seal replacer.
- Reinstall the camshaft sprockets and the camshaft timing belt.
Reinstall the valve cover as follows:
- Clean the gasket sealing surfaces.
- Inspect the valve cover gasket and O-rings, replace as required.
- Reinstall the valve cover retaining bolts and tighten in a standard sequence starting from the center and working towards the outside of the valve cover to 53-71 inch lbs. (6-8 Nm).
- Reinstall the upper camshaft timing belt cover and tighten the retaining bolts to 27-44 inch lbs. (3-5 Nm).
- Reinstall the power steering hose retaining bracket and the power steering hose.
- Reinstall the ignition wires.
- Reinstall the crankcase ventilation tube to the valve cover.
- Reinstall the engine air intake resonators.
- Reconnect the negative battery cable.
- Run the engine and check for leaks and proper operation.
See Figures 11, 12 and 13
- Disconnect the negative battery cable.
Remove both valve covers as follows:
- Remove the ignition wires and spark plugs.
- Remove the ignition coil from the right valve cover.
- Remove the crankcase ventilation tubes from both valve covers.
- Remove the wiring harness and bracket to the fuel injectors and move aside.
- Remove the retaining nuts and engine wiring from both valve covers and move aside.
- Loosen the valve cover retaining bolts and studs, in sequence.
- Remove both valve covers from the engine.
- Remove the engine front cover.
- Remove the timing chains.
- Remove the camshaft journal thrust caps.
- Loosen the camshaft journal cap bolts in sequence, in several passes, to allow the camshaft to raise off of the cylinder head evenly.
- Remove the camshaft journal caps with the retaining bolts installed.
- Remove the camshafts from the cylinder head. If necessary, remove the rocker arms, marking their position so they can be reinstalled in their original locations.
- Repeat the procedure for both cylinder heads.
- Inspect the camshafts and bearing journals for wear or damage.
- Rotate the crankshaft so that the key-way is at the 11 o'clock position for installation of the camshafts.
- Reinstall the rocker arms, if removed.
- Lubricate the camshafts with engine assembly lubricant.
- Reinstall the camshafts into their correct positions into each cylinder head with the timing marks on the camshaft sprockets aligned.
- Loosely install the camshaft journal caps and retaining bolts into their correct positions.
Do not install the camshaft journal thrust caps until the rocker arms and timing chains have been installed and the camshaft journal caps are secured into position.
- Reinstall the rocker arms.
- Reinstall the timing chains.
- Tighten the camshaft journal cap bolts, in the opposite order of the removal sequence, to 71-106 inch lbs. (8-12 Nm). Reinstall the thrust caps and tighten the retaining bolts to 71-106 inch lbs. (8-12 Nm).
- Reinstall the engine front cover.
Reinstall both valve covers as follows:
- Clean the valve cover gasket sealing surfaces.
- Reinstall new valve cover gaskets onto the valve covers.
- For each valve cover, place a bead of silicone sealant at the two places on the valve cover sealing surfaces where the engine front cover and the cylinder heads make contact and at two places on the rear of the cylinder head where the camshaft seal retainer contacts the cylinder head.
- Reinstall the valve cover retaining bolts and studs and tighten in sequence to 71-106 inch lbs. (8-12 Nm).
The valve covers must be installed and properly tightened within six minutes of applying the silicone sealant.
- Reconnect the negative battery cable.
- Run the engine and check for leaks and proper engine operation.
Camshaft Lobe Lift
Camshaft lobe lift is the amount (measured in inches or millimeters) that the camshaft is capable of LIFTING the valve train components in order to open the valves. The lobe lift is a measure of how much taller the "egg shaped'' portion of the camshaft lobe is above the base or circular portion of the shaft lobe. Lift is directly proportional to how far the valves can open and a worn camshaft (with poor lobe lift) cannot fully open the valves. The lobe lift therefore can be directly responsible for proper or poor engine performance.
Lobe lift can be measured in 2 ways, depending on what tools are available and whether or not the camshaft has been removed from the engine. A dial gauge can be used to measure the lift with the camshaft installed, while a micrometer is normally only used once the shaft has been removed from the engine.DIAL GAUGE METHOD
Lobe lift may be checked with the camshaft installed. In all cases, a dial gauge is positioned somewhere on the valve train (pushrod, lifter, or camshaft itself) and the camshaft is then turned to measure the lift.
Check the lift of each lobe in consecutive order and make a note of the reading.
- Remove the valve cover for access to the camshaft.
- Install a dial indicator so that the actuating point of the indicator is directly placed on the camshaft.
A remote starter can be used to turn the engine over during the next steps. If a remote starter is not available, remove the spark plugs in order to relieve engine compression, and turn the engine over using a large wrench or socket on the crankshaft damper bolt. BE SURE to only turn the engine in the normal direction of rotation.
- Turn the crankshaft over until the tappet is on the base circle of the camshaft lobe.
- Zero the dial indicator. Continue to rotate the crankshaft slowly until the pushrod (or camshaft lobe) is in the fully raised position.
- Compare the total lift recorded on the dial indicator with the elevation specification shown in the Engine Specification chart.
To check the accuracy of the original indicator reading, continue to rotate the crankshaft until the indicator reads zero. If the lift on any lobe is below specified wear limits listed, the camshaft and the valve tappets must be replaced.
- Install the valve cover(s).
See Figure 14
A micrometer may used to measure camshaft lobe lift, but this is usually only after it has been removed from the engine. Once the valve cover is removed from the, access may be possible (though a l