The correct installation and adjustment of the camshaft drive belt is mandatory if the engine is to run properly. When any given piston is on the intake stroke the corresponding intake valve must be open to admit air/fuel mixture into the cylinder. When the same piston is on the compression and power strokes, both valves in that cylinder must be closed. When the piston is on the exhaust stroke, the exhaust valve for that cylinder must be open. If the opening and closing of the valves is not coordinated with the movements of the pistons, the engine will run very poorly, if at all.
The camshaft drive belt also turns the engine auxiliary shaft. The distributor is driven by the engine auxiliary shaft. Since the distributor controls ignition timing, the auxiliary shaft must be coordinated with the camshaft and crankshaft, since both valves in any given cylinder must be closed and the piston in that cylinder near the top of the compression stroke when the spark plug fires.
Due to this complex interrelationship between the camshaft, the crankshaft and the auxiliary shaft, the cogged pulleys on each component must be aligned when the camshaft drive belt is installed.
REMOVAL & INSTALLATION
See Figures 1 and 2
- Set the engine to TDC as described in the troubleshooting section. The crankshaft and camshaft timing marks should align with their respective pointers and the distributor rotor should point to the No. 1 plug tower.
- Disconnect the negative battery cable, then properly drain the engine cooling system.
- Remove the timing belt front cover, as outlined in this section.
- Loosen the belt tensioner adjustment screw, position belt tensioner tool T74P-6254-A or equivalent, on the tension spring roll pin and release the belt tensioner. Tighten the adjustment screw to hold the tensioner in the released position.
- Remove the crankshaft pulley, hub and belt guide. Remove the timing belt. If the belt is to be reused, mark the direction of rotation so it may be reinstalled in the same direction.
- Position the crankshaft sprocket to align with the TDC mark and the camshaft sprocket to align wit the camshaft timing pointer.
- Install the timing belt over the crankshaft sprocket, then counterclockwise over the auxiliary shaft and the camshaft sprockets. Align the belt fore-and-aft so that it is centered on the sprockets.
- Loosen the tensioner adjustment bolt to allow the tensioner to move against the belt. If the spring does not have enough tension to move the roller against the belt, it may be necessary to manually push the roller against the belt and tighten the bolt.
- To make sure the belt does not jump time during rotation in the next step, remove a spark plug from each cylinder.
- Rotate the crankshaft two complete turns in the direction of normal rotation to remove any slack from the belt. Tighten the tensioner adjustment to 29-40 ft. lbs. (40-55 Nm) and pivot bolts to 14-22 ft. lbs. (20-30 Nm). Check the alignment of the timing marks.
- Install the crankshaft belt guide. Install the crankshaft pulley and tighten the retaining bolt.
- Install the timing belt front cover, spark plugs and remaining components.
- Fill the cooling system, then connect the negative battery cable. Start the engine and check for proper operation. Check the coolant level and add if necessary. Check and adjust the ignition timing, if necessary.