Timing Chain, Sprockets, Front Cover and Seal

Removal & Installation

To Remove:

NOTE: Timing chain replacement requires the engine to be removed. Remove the engine prior to replacing the timing chains. Timing the engine can be performed in-vehicle when the chains are not being replaced.

NOTE: You must retime the camshafts when either camshaft timing is disturbed.

1. Remove the intake manifold.
2. Remove the valve covers.
3. Remove the fuel supply manifold.
4. Remove the engine front cover.
5. Remove the thermostat housing.
6. Remove all roller followers.
7. Remove the left-hand camshaft chain tensioner.
8. Install the camshaft sprocket holding tool (303-564) and the adapter for tool 303-564 (303-578) to hold the camshaft sprocket.
9. Loosen but do not remove the left hand camshaft sprocket retaining bolt.
10. Remove the camshaft sprocket holding tool and bolt.
11. Loosen the jackshaft sprocket bolt while preventing the crankshaft from turning.

    Remove the jackshaft sprocket-4.0L Engine

12. Remove the primary chain tensioner.
13. Remove the primary chain and sprocket.
14. Remove the camshaft drive cassette by removing the chain guide bolts, removing the sprockets, then lifting the chain and guiding up and out of the cylinder head.
15. Be sure that all gasket mating surfaces and the engine are clean and free of debris.

To Install:

1. Install the chain guide through the cylinder head.
2. Install the chain.
3. Install the new chain guide bolts.
   • Torque the upper bolt to 9 ft. lbs (12 Nm).
   • Torque the lower bolt to 14 ft-lb (19 Nm).

   Timing chain & guides

   NOTE: The camshaft chain sprockets must be orientated correctly.

4. Install the lower chain sprocket.
5. Install the camshaft sprocket.
6. Install the camshaft sprocket bolt. Do not tighten at this time.
7. Install the primary chain and gear.
8. Install the primary drive chain tensioner.
   • Torque bolts to 80 in. lbs (9 Nm).
9. Tighten the jackshaft sprocket bolt in two steps while preventing the crankshaft from turning:
   • Step 1: Torque to 33 ft-lb (45 Nm).
   • Step 2: Tighten the bolts an additional 90°.
10. Install the engine front cover.
11. Time the engine.