Timing Chain: Service and Repair

REMOVAL
1. Remove timing chain cover and gasket using extreme caution to avoid damaging oil pan gasket.
2. Align camshaft and crankshaft centerline. Remove camshaft sprocket attaching bolt and remove timing chain and camshaft sprockets.





3. Use puller 6444 and jaws 6820 to remove crankshaft sprocket (Fig. 79).

INSPECTION-MEASURING TIMING CHAIN STRETCH
1. Place a scale next to the timing chain so that any movement of the chain may 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 a 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. 80).
4. Install a new timing chain, if its movement exceeds 3.175 mm (1/8 inch).

INSTALLATION





1. Line up key in crankshaft with keyway in sprocket, press on crankshaft timing sprocket, use tools C-3688, C-3718 and MB-990799, seat sprocket against crankshaft shoulder (Fig. 81).
2. Turn crankshaft to line up the timing mark with the crankshaft and camshaft centerline.
3. Put chain on camshaft sprocket.





4. Align timing marks and install chain and camshaft sprocket onto crankshaft sprocket. Check to see that timing marks are on the centerline of the crankshaft and camshaft centerline (Fig. 82).
5. Install the camshaft bolt. Tighten the bolt to 61 Nm (45 ft. lbs.) torque.
6. Check camshaft end play. The end play should be 0.051 - 0.152 mm (0.002 - 0.006 inch) with a new thrust plate and up to 0.254 mm (0.010 inch) with a used thrust plate. If not within these limits install a new thrust plate.
7. Install timing chain cover.