Timing Belt Tensioner: Service and Repair

This article has been revised according to the information included in bulletin No: 47-61-34.

NOTE: GM does not provide a timing mark diagram for belt installation without using the special tool(s) listed below.

TIMING BELT AND TENSIONER REPLACEMENT

(figure 1) Timing Marks:

(Figure 2) Crankshaft Reference Marks:

(figure 3) Tensioner Assembly:

(figure 4) Tensioner Tool Fabricated From Paper Clip:

SPECIAL TOOLS REQUIRED (or equivalents)
- J-38613-A, Camshaft timing clamps.

REMOVE OR DISCONNECT
1. Negative battery cable.
2. Air cleaner assembly.
3. Drain engine coolant.
4. Accelerator and cruise control cables from throttle-body.
5. Fuel rail cover.
6. Relieve fuel pressure.
7. Fuel lines from fuel rail and remove fuel mounting bracket.
8. Heater hose and bracket from lower intake manifold.
9. Positive Crankcase Ventilation (PCV) valve and vacuum line from throttle body.
10. Electrical connector from Exhaust Gas Recirculation (EGR).
11. EGR valve and reposition.
12. Electrical connections from canister purge solenoid and Manifold Absolute Pressure (MAP) sensor.
13. Vacuum lines from upper intake manifold tee.
14. Wiring loom bracket for rear spark plug wires.
15. Power brake vacuum hose and remove upper intake manifold.
16. Coolant recovery tank.
17. Serpentine belt and tensioner.
18. Power steering lines from pump and reposition for pump removal.
19. Powertrain Control Module (PCM) electrical connectors.
20. Reposition PCM.
21. Spark plug wires from spark plugs.
22. Wiring harness cover at right strut tower.
23. Fuel line bracket.
24. Timing belt covers.
25. Breather hose from rear camshaft cover and crankcase vent from breather manifold.
26. Camshaft carrier covers.
27. Side plate bolts from actuator.
28. Rotate actuator assembly from the tensioner pulley socket and out of the mounting base.
29. Timing belt tensioner pulley.
30. Position actuator in vertical position in vise (rod tip down) and clamp actuator body in vise lightly, (figure 3).

NOTES:
^ Allow oil to drain to boot end for at least 5 minutes prior to refilling.
^ The actuator assembly uses a tapered bushing between the actuator and mounting base. Do not lose or damage the bushing when removing the actuator assembly.

31. Straighten out a standard paper clip (0.032 inch diameter, no serrations) to a minimum straight length of 47 mm (1.85 inches). Form a double loop in the remaining end of the paper clip, (figure 4).
32. Rubber end plug from the rear of the actuator assembly. The assembly is filled with oil and removal of the plug may allow oil to escape. DO NOT REMOVE VENT LUG.
33. Push the paper clip through the center of the vent plug and into the pilot hole.
34. Insert a small screwdriver into the screw slot inside the actuator, behind the rubber end plug.
35. Retract actuator plunger by rotating screw in a clockwise direction, until it is fully retracted. Push on paper clip and slowly rotate screw counterclockwise until paper clip engages.
36. Timing belt by carefully sliding it off the pulleys.

NOTES:
^ Remove timing marks from camshaft and intermediate shaft sprockets.
^ Do NOT bend, kink, twist, or pry on a new or used belt as damage may occur. "Kinking" is folding belt so that the diameter at any point is less than 60 mm (2.36 inch).

37. Rotate crankshaft so the # 1 cylinder is at TDC (top dead center). Mark the timing indicator with white paint (or equivalent) on the crankshaft balancer and front cover.
38. Position camshafts so the flat spots are "up" for installation of J-38613-A.
39. Install J-38613-A on both camshaft carriers.

INSTALL OR CONNECT
1. Timing belt in a counterclockwise direction around the sprockets. Make sure timing belt teeth are fully engaged with all sprockets.
2. Timing belt tensioner pulley and tighten tensioner pulley bolt to 50 Nm (37 lb ft).
3. If actuator oil has been lost, fill the actuator with SAE 5W-30 Mobil 1 (or equivalent) synthetic engine oil through the end hole. Fill to bottom of plug hole ONLY when actuator is fully retracted and pin is installed.
4. Rubber end plug to rear of the actuator assembly. Push until flush and snapped into place. Make sure the end plug has sealed against the case.
5. Actuator bushing into side plate.
Inspect: Bushings and appropriate holes to make sure they are clean. DO NOT lubricate.
6. Timing belt actuator and actuator side plate and tighten side plate bolt to 27 Nm (20 lb ft).

NOTE: Rotate pulley assembly into belt a maximum of 15 Nm to allow engagement of the actuator shaft into the pulley arm socket.

7. Pull the lock pin and discard. Retorque pulley assembly 15 Nm counterclockwise to seat pulley into belt.
Tighten: Both right hand (rear bank) camshaft sprocket bolts to 130 Nm (96 lb ft).
8. Remove J-38613-A from right hand (rear bank) camshaft carrier.
9. Rotate crankshaft 360 degrees clockwise while looking at front of engine and align crankshaft reference marks.
Inspect: Make sure both right hand (rear bank) camshaft flats are down.
Tighten: Both left hand (front bank) camshaft sprocket bolts to 130 Nm (96 lb ft).
10. Remove J-38613-A from left hand (front bank) camshaft carrier.
11. Rotate crankshaft 720 degrees clockwise while looking at front of engine to seat timing belt and verify correct timing.
Inspect: Make sure both camshaft flat spots are up on one bank and down on the opposing bank.
12. Camshaft carrier covers and bolts and tighten to 11 Nm (97 lb In).
13. Breather hose from rear camshaft cover and crankcase vent from breather manifold.
14. Timing belt covers and bolts and tighten to 10 Nm (89 lb in).
15. Fuel line bracket and bolt and tighten to 7 Nm (62 lb In).
16. Wiring harness cover at right strut tower.
17. Spark plug wires.
18. PCM electrical connectors.
19. Power steering lines to pump.
20. Serpentine belt.
21. Serpentine belt tensioner and tighten bolt to 45 Nm (33 lb ft).
22. Coolant recovery tank.
23. Upper intake manifold, bolts, and nuts and tighten bolts and nuts to 27 Nm (22 lb ft).
24. Power brake vacuum hose.
25. Wiring loom bracket for rear spark plug wires.
26. Vacuum lines to upper intake manifold tee.
27. Electrical connections to canister purge solenoid and MAP sensor.
28. EGR valve and bolts, tighten to 25 Nm (18 lb ft).
29. Electrical connectors from EGR.
30. PCV valve and vacuum line to throttle body.
31. Heater hose and bracket to lower intake manifold.
32. Fuel mounting bracket and bolt.
33. Fuel lines to fuel rail and install fuel rail cover.
34. Accelerator and cruise control cables to throttle-body.
35. Air cleaner assembly.
36. Refill cooling system and power steering systems.
37. Negative battery cable.