Timing Belt: Service and Repair

***UPDATED BY TSB 1118851097Z, 10/87

NOTE: If the timing belt has to be loosened when performing a repair, do not reuse the belt, it must be replaced.
Reusing and retensioning the drive belt could cause the internal fibers to be over-stretched, and significantly weakened. This could greatly increase the likelyhood of a premature belt failure, and subsequent engine damage.


1. Disconnect battery ground cable, then drain cooling system.
2. Disconnect upper radiator hose, then remove fan shroud.
3. Remove accessory drive belts, then the fan and clutch assembly.
4. Remove crankshaft pulley and vibration damper retaining bolts, then the pulley and damper.
5. Disconnect heater hose from thermostat housing.
6. Remove timing belt cover-to-crankcase attaching bolts, then the cover.
7. Remove valve cover.

Fig. 1 TDC aligning pin installed:

8. Rotate engine until No. 1 cylinder is at TDC compression stroke, then install TDC aligning pin, Fig. 1.

Fig. 5 Camshaft positioning tool installation:

9. Install suitable camshaft positioning tool onto cylinder head, Fig. 5. Flat side of nut or cam position tool should be facing down.
10. Loosen camshaft sprocket bolt.
11. If old belt will be reinstalled/installed, mark direction of engine rotation on belt.
12. Loosen belt tensioner attaching bolts, then remove timing belt.
13. If using new belt or belt with less than 10,000 miles, insert .098 inch feeler gauge between camshaft positioning tool, Fig. 5, and right corner of cylinder head.

Fig. 6 Injection pump aligning pin installation:

14. Install injection pump aligning pin through injection pump sprocket, Fig. 6.

Fig. 7 Timing belt installation:

15. Rotate camshaft sprocket clockwise against aligning pin, then install timing belt. Starting at crankshaft sprocket, route belt around intermediate shaft sprocket, injection pump sprocket, camshaft sprocket and tension roller, Fig. 7. Ensure V side of belt is correctly positioned in pulley V.
16. Hand tighten belt tensioner until all slack is removed from timing belt.
17. Remove injection pump aligning pin.
18. Torque belt tensioner to 35 ft.lbs. for belts with less than 10,000 miles, or 24 ft.lbs. for belts greater than 10,000 miles.
19. torque belt tensioner attaching bolts to 17 ft.lbs.
20. Torque camshaft sprocket bolt to 44 ft.lbs.
21. Reverse steps 1 through 9 complete installation. Torque crankshaft pulley and vibration damper retaining bolts to specification.
22. Adjust injection pump timing.