Timing Chain: Service and Repair

REMOVAL
1. Disconnect battery negative cable.
2. Drain cooling system.
3. Remove timing chain cover.





4. Rotate crankshaft to align timing marks (Fig. 81) to #1 TDC.
5. Remove camshaft sprocket attaching bolt and remove timing chain with crankshaft and camshaft sprockets.





6. Slip crankshaft sprocket onto crankshaft and compress tensioner shoe by placing a large screwdriver between crankshaft sprocket and tensioner shoe (Fig. 80). Compress shoe until hole in shoe lines up with hole in bracket. Slide a suitable pin into the holes (Fig. 80) and remove screwdriver.
7. If tensioner assembly is to be replaced, remove the three tensioner to block bolts and remove tensioner assembly.

INSPECTION-MEASURING TIMING CHAIN STRETCH

NOTE: Timing chain tensioner must be removed for this operation.

1. Place a scale next to the timing chain so that any movement of the chain can be measured.
2. Place a torque wrench and socket over camshaft sprocket attaching bolt. Apply torque in the direction of crankshaft rotation to take up slack; 41 Nm (30 ft. lbs.) torque with cylinder head installed or 20 Nm (15 ft. lbs.) torque with cylinder head removed. With torque applied to the camshaft sprocket bolt, crankshaft should not be permitted to move. It may be necessary to block the crankshaft to prevent rotation.





3. Hold a scale with dimensional reading even with the edge of a chain link. With cylinder heads installed, apply 14 Nm (30 ft. lbs.) torque in the reverse direction. With the cylinder heads removed, apply 20 Nm (15 ft. lbs.) torque in the reverse direction. Note the amount of chain movement (Fig. 82).
4. Install a new timing chain, if its movement exceeds 3.175 mm (1/8 inch).

INSTALLATION
1. If tensioner assembly is being replaced, install tensioner and mounting bolts. Torque bolts to 24 Nm (210 in. lbs.).
2. Place both camshaft sprocket and crankshaft sprocket on the bench with timing marks on an exact imaginary center line through both camshaft and crankshaft bores.
3. Place timing chain around both sprockets.
4. Lift sprockets and chain (keep sprockets tight against the chain in position as described).





5. Slide both sprockets evenly over their respective shafts and verify alignment of timing marks (Fig. 83) with a straight-edge if necessary.
6. Install the camshaft bolt. Tighten the bolt to 68 Nm (50 ft. lbs.) torque.
7. Remove tensioner pin. Again, verify alignment of timing marks.
8. Install timing cover.
9. Fill cooling system.
10. Connect battery negative cable.
11. Start engine and check for oil and coolant leaks.