The correct installation and adjustment of the camshaft drive belt is critical 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. In order to prevent an unanticipated breakdown, and possible engine damage, it is recommended that the camshaft drive belt be replaced every 60,000 miles (97,000 km).
Should the camshaft drive belt jump timing by a tooth or two, the engine could still run; but very poorly. To visually check for correct timing of the crankshaft, auxiliary shaft and the camshaft, follow this procedure:
There is an access plug provided in the cam drive belt cover, so that the camshaft timing can be checked without removing the cover.
- Remove the access plug.
- Turn the crankshaft until the timing marks on the crankshaft indicate TDC.
- Make sure that the timing mark on the camshaft drive sprocket is aligned with the pointer on the inner belt cover. Also, the rotor of the distributor must align with the No. 1 cylinder firing position.
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.
- Loosen the adjustment bolts on the alternator and other belt-driven accessories, and remove the drive belts. To provide clearance for removing the belt outer cover and camshaft belt, remove the fan (if applicable) and pulley from the water pump hub.
- Reposition the fuel vapor tube running to the evaporator canister, if necessary, to provide clearance for cover removal.
- Remove the belt outer cover attaching bolt.
- Remove the belt outer cover.
- Remove the distributor cap from the distributor and position it out of the way.
- Loosen the belt tensioner adjustment and pivot bolts. Lever the tensioner away from the belt and retighten the adjustment bolt to hold it away.
- Remove the crankshaft bolt and pulley. Remove the belt guide behind the pulley.
- Remove the camshaft drive belt.
- Install the new belt over the crankshaft sprocket first, then counterclockwise over the auxiliary shaft sprocket and the camshaft sprocket. Adjust the belt fore and aft so that it is centered on the sprockets.
- Loosen the tensioner adjustment bolt, allowing it to spring back against the belt.
- Rotate the crankshaft two complete turns in the normal rotational direction to remove any belt slack. Turn the crankshaft until the timing check marks are lined up. If the timing has slipped, remove the belt and repeat the procedure.
- Tighten the tensioner adjustment bolt to 14-21 ft. lbs. (18-27 Nm), and the pivot bolt to 28-40 ft. lbs. (36-52 Nm).
- Install the distributor cap.
- Install the belt guide, belt outer cover and crankshaft pulley. Install the water pump pulley and, if applicable, the cooling fan.
- Install the drive belts and accessories and adjust the drive belt tension. Reposition the fuel vapor tube, if necessary.
- Start the engine and check the ignition timing.