REMOVAL & INSTALLATION
See Figures 1 and 2
- Disconnect the negative battery cable and drain the cooling system.
- Remove the air intake and the throttle body.
- Disconnect the radiator hoses. Remove the cooling fan and shroud assembly.
- Tag and disconnect the spark plug wires, then position aside.
- Tag and disengage the necessary electrical connectors and vacuum lines, positioning them aside for clearance.
- Remove the rocker arm cover retaining bolts and the rocker cover.
- Remove the timing belt front cover.
- Remove the timing belt.
- Compress the valve springs using valve spring compressor lever T88T-6565-BH, or equivalent, and remove the cam followers (rocker arms).
- Remove the camshaft sprocket retaining bolt. Remove the camshaft sprocket using a suitable puller. Remove the camshaft seal using a seal removal tool.
- Remove the two screws and the camshaft rear retainer.
- Raise and support the vehicle safely using jackstands. Be sure to position the vehicle at a height which will allow access both above and below the engine.
- Remove the right and left engine support bolts and nuts.
- Position a block of wood and a jack under the engine. Raise the engine as high as it will go. Place blocks of wood between the engine mounts and chassis brackets. If the vehicle is supported at a height allowing access above and below the engine, you can leave the jack in position.
- Remove the camshaft slowly and carefully to prevent damage to the lobes, journals or bearings.
- Inspect the lobes and bearings for damage or wear. Replace the camshaft and bearings, as necessary.
- If camshaft bearing replacement is necessary, you will have to rent or buy a bearing removal and installation tool. Essentially the tool is a threaded rod with a pulling plate and nut, along with various size drivers to push the bearings out of or pull the bearings into position.
- Make sure the threaded plug is in the rear of the camshaft. If you are replacing the camshaft, you may have to remove the plug from the old camshaftand install it in the new one.
- Coat the camshaft lobes with multi-purpose grease and lubricate the journals with heavy engine oil before installation. An engine assembly lube can also be used. Carefully slide the camshaft through the bearings.
- Install the camshaft rear retainer and tighten the two screws to 6-9 ft. lbs. (8-12 Nm). Install a new camshaft seal using a suitable seal installer.
- Install the camshaft sprocket and tighten the retaining bolt to 52-70 ft. lbs. (70-95 Nm).
- Install the timing belt.
- Install the timing belt front cover.
- Raise the engine with the jack and block of wood used earlier. Remove the blocks of wood, lower the engine and remove the jack.
- Install the engine support bolts and nuts, then remove the jackstands and carefully lower the vehicle.
- Install the rocker arm cover.
- Engage the electrical connectors and vacuum lines as tagged earlier.
- Connect the spark plug wires as tagged earlier.
- Install the cooling fan and shroud assembly.
- Connect the radiator hoses.
- Install the throttle body and the air intake.
- Connect the negative battery cable, then properly refill the engine cooling system.
- Run the engine and check for leaks.
- On the distributor equipped (VIN A) engine, check the ignition timing.
See Figure 3
If your vehicle is equipped with A/C, you will have to take the car to a service station to have the refrigerant discharged and recovered (using a proper recycling/recovery station) before beginning this procedure.
- Properly discharge and recover the A/C refrigerant using a recovery station.
- Disconnect the negative battery cable for safety.
- Drain the cooling system and relieve the fuel system pressure.
- Remove the radiator. If equipped with air conditioning, remove the condenser.
- Remove the grille.
- Remove the upper and lower intake manifold assembly.
- Remove the rocker arm covers.
- Remove the pushrods and lifters.
Keep track of all valve train components. Any components which are to be reused, such as pushrods or lifters, must be reinstalled in their original locations. If necessary sort or label them during removal to assure installation in their correct positions.
- Remove the timing chain front cover.
- Remove the timing chain and gears.
- Remove the thrust plate. Remove the camshaft, being careful not to damage the bearing surfaces.
- Lubricate the camshaft lobes and journals with heavy engine oil or a suitable engine assembly lube. An engine assembly lube is preferable if some time may pass before the job is completed and the engine is started. Install the camshaft, being careful not to damage the bearing surfaces while sliding it into position.
- Install the camshaft thrust plate with the groove toward the cylinder block. Tighten the bolts to 9-12 ft. lbs. (12-16 Nm).
- Check the camshaft play to determine whether or not the thrust plate must be replaced.
- Install the lifters and pushrods.
When reinstalling a camshaft, make sure the lifters and pushrods are installed in their original locations. If a new camshaft is being installed, new lifters and pushrods should be used.
- Install the timing chain and gears.
- Install the engine front cover.
- Install the rocker arm covers.
- Install the upper and lower intake manifolds.
- Install the grille. If equipped with air conditioning, install the condenser.
- Install the radiator.
- Connect the negative battery cable, then fill and bleed the engine cooling system.
- Run the engine and check for leaks.
Camshaft Lobe Lift
Camshaft lobe lift is the amount (measured in in. or mm) that the camshaft is capable of LIFITING 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. The dial gauge can be used to measure the lift with the camshaft installed, while the micrometer is normally only used once the shaft has been removed from the engine.DIAL GAUGE
See Figure 4
On both the 2.3L and 5.0L engines, lobe lift may be checked with the camshaft installed. In both 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 rocker arm cover for access to the camshaft (2.3L) or pushrods (5.0L).
- On the 5.0L engine, either remove the rocker arms (remember to tag or arrange them for proper installation), or loosen their mounting and reposition them for access to the pushrods. Make sure the pushrod is in the valve tappet socket.
- Install a dial indicator D78P-4201-B or equivalent. so that the actuating point of the indicator is in the pushrod socket (or the indicator ball socket adaptor tool 6565-AB is on the end of the pushrod) and in the same plane as the pushrod movement. On the 2.3L engine, the dial indicator may be 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 (one from each cylinder on the 2.3L engine) 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, especially on the 2.3L (TIMING BELT) engine.
- Turn the crankshaft over until the tappet is on the base circle of the camshaft lobe. At this position on the 5.0L engine, the pushrod will be at its lowest point of travel.
- 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 on the Camshaft 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 tappet operating on the worn lobe(s) must be replaced.
- When you are finished, install the rocker arms (5.0L engine) and check the valve clearance.
- Install the rocker arm cover(s).
See Figures 5 and 6
A micrometer may used to measure camshaft lobe lift, but this is usually only after it has been removed from the engine. Once the rocker arm cover is removed from the 2.3L engine, access may be possible (though a little awkward) to measure the camshaft lobes using a micrometer.
In any case, 2 measurements are necessary for each lobe. Measurement Y or the total LOBE HEIGHT and measurement X or the total LOBE WIDTH. To find the lobe lift, you simply subtract X from Y (subtract the width from the height).
Note each measurement, then make your calculation to determine the lift. Note the final results and repeat the process on the remaining camshaft lobes. Finally, you should compare your results to the specifications charts and decide if a new camshaft is in your future.Camshaft End-Play
On all gasoline V8 engines, prying against the aluminum-nylon camshaft sprocket, with the valve train load on the camshaft, can break or damage the sprocket. Therefore, the rocker arms must be loosened sufficiently to free the camshaft. After checking the camshaft end-play, check the valve clearance. Adjust if required (refer to the procedure in General Information & Maintenance in this repair guide for more details).
- Push the camshaft toward the rear of the engine. Install a dial indicator (Tool D78P-4201-F, -G or equivalent) so that the indicator point is on the camshaft sprocket attaching screw.
- Zero the dial indicator. Position a prybar between the camshaft gear and the block. Pull the camshaft forward and release it. Compare the dial indicator reading with the specifications.
- If end-play is excessive, check the spacer for correct installation before it is removed. If the spacer is correctly installed, replace the thrust plate.
- Remove the dial indicator.