Timing Belt: Service and Repair

Replace timing belt every 60,000 miles or every five years to prevent cylinder head, valve train or piston damage.
Removal
1. Remove lefthand front and side undercover.
2. Disconnect and remove cruise control pump and link assembly.
3. Remove alternator assembly.
4. Raise and support engine assembly to take weight off engine mounts.

Fig. 42 Timing Belt Removal. DOHC:

Fig. 35 Removing Engine Support Bracket. SOHC:

5. Remove timing belt in order shown in Fig. 42, noting the following:
a. Remove crankshaft pulley using end yoke holder tool No. MB990767 and crankshaft pulley holder tool No. MB998754, or equivalent.
b. Remove engine mount bracket in sequence shown in Fig. 35, lubricating reamer bolt indicated by arrow then remove bolt slowly. Reamer bolt is sometimes heat seized on engine support bracket.
c. Align timing marks prior to timing belt removal.
d. Mark rotation direction on timing belt for installation if belt is to be reused.
e. Loosen timing belt tensioner center bolt.
f. Remove timing belt.

INSTALLATION

1. Reset auto tensioner by placing auto tensioner level in a soft jawed vise.

Fig. 43 Aligning Set Holes. DOHC:

2. Push rod inward until set hole marked A is aligned with set hole marked B, Fig. 43.
3. Insert a .055 inch diameter wire into set holes.
4. Remove tensioner from vise then install tensioner onto engine.

Fig. 44 Aligning Timing Marks. DOHC:

5. Align timing marks for camshaft sprockets on the rear bank, Fig. 44.

Fig. 45 Rear Camshaft Alignment Position. DOHC:

Fig. 46 Positioning Camshaft Sprockets. DOHC:

6. Align timing marks for camshaft sprockets on the front bank, as follows:
a. Install the crankshaft pulley. Shift timing mark on crankshaft sprocket by three teeth to lower piston in No. 1 cylinder slightly from top dead center. Turning camshaft sprocket with piston in No. 1 cylinder located at TDC may cause valves to interfere with piston.
b. Make sure that timing marks on camshaft sprockets for intake and exhaust valves are not within range marked A, Fig. 45. If timing mark is within range marked A, turn camshaft sprocket to move timing mark to area closest to range marked A. In range marked A, the cam lobe on the camshaft lifts the valve through the rocker arm and the camshaft sprocket is apt to rotate by reaction force of the valve spring.
c. Turn camshaft sprocket to locate timing mark as shown in Fig. 46. If the intake and exhaust valves of the same cylinder lift simultaneously, interference with each other may result. Therefore, turn the intake camshaft sprocket and the exhaust camshaft sprocket alternately.
d. Turn camshaft sprocket clockwise to align the timing marks. If camshaft sprocket has been turned excessively, turn sprocket counterclockwise to align timing marks.
e. Align timing mark of the crankshaft sprocket. Shift timing mark of crankshaft sprocket one tooth in counterclockwise direction to install timing belt.

Fig. 47 Timing Belt Installation. DOHC:

7. Using paper clips to hold timing belt in place, install timing belt in order shown in Fig. 47, ensuring not to allow belt to slack.
8. Turn tensioner pulley so that its pin holes are located above the center bolt. Press tensioner pulley against timing belt and temporarily tighten center bolt.
9. Ensure timing marks on all sprockets are aligned properly then remove clips.
10. Adjust timing belt by rotating crankshaft 1/4 turn counterclockwise, then rotate it clockwise until timing marks are aligned.

Fig. 48 Tightening Tensioner Pulley Bolt. DOHC:

11. Loosen tensioner pulley center bolt. Using tensioner pulley socket wrench tool No. MB998767, or equivalent, apply 7.2 ft lbs of torque to the timing belt and tighten tensioner pulley center bolt to specification, Fig. 48.
12. Remove set pin from auto tensioner and ensure the set pin can be easily removed.
13. Rotate crankshaft two times and leave it for five minutes or more. Ensure again that the set pin can be easily removed from and installed to the auto tensioner.

Fig. 49 Tightening Tensioner Pulley Bolt. DOHC:

14. Ensure tensioner rod protrusion is within 0.149 - 0.177 inch, Fig. 49 If rod is out of specification repeat steps 5 through 9.
15. Ensure timing marks are aligned on all sprockets.

Fig. 50 Installing Lower Timing Belt Cover. DOHC:

16. Install lower timing belt cover bolts as shown in Fig. 50.

Fig. 51 Installing Engine Support Bracket. DOHC:

17. Install engine support bracket bolts in sequence shown in Fig. 51.
18. Reverse remaining removal procedure to install.