Intake Manifold Replacement - Lower

Intake Manifold Replacement - Lower
Removal Procedure

Important: This engine uses a sequential multiport fuel injection system. Injector wiring harness connectors must be connected to their appropriate fuel injector or exhaust emissions and engine performance may be seriously affected.

1. Remove the coolant crossover pipe.
2. Remove the upper intake manifold.
3. Remove the left valve rocker arm cover.
4. Remove the right valve rocker arm cover.
5. Disconnect the engine coolant temperature (ECT) electrical connector.
6. Disconnect the fuel feed line from the fuel rail.





7. Disconnect the fuel injector inline connector (2).





8. Remove the fuel injector harness connector bracket bolt from the intake manifold.
9. Disconnect the camshaft position (CMP) sensor electrical connector.
10. Remove the fuel injector rail bolts.
11. Remove the fuel rail.





12. Remove the lower intake manifold bolts.
13. Remove the lower intake manifold.





14. Loosen the valve rocker arm bolts.

15. Important: Place the valve train components in a rack in order to ensure that the components are installed in the same location from which they where removed.

Remove the valve rocker arms.
16. Remove the push rods.
^ The intake push rods measure 147.51 mm (5.81 inch).
^ The exhaust push rods measure 154.87 mm (6.1 inch).





17. Remove the lower intake manifold gaskets and seals.
18. Clean the lower intake manifold gasket and seal surfaces on the cylinder heads and the engine block.
19. Clean the gasket and seal surfaces on the lower intake manifold with degreaser.
20. Remove all the loose room temperature vulcanizing sealer (RTV) (1).

Installation Procedure

Important: All gasket mating surfaces need to be free of oil and foreign material. Use GM P/N 12346139 (Canadian P/N 10953463) or equivalent, to clean the surfaces.





1. Important: RTV sealer is NOT to be placed under the lower intake manifold gaskets.

Install the lower intake manifold gaskets and seals.





2. Coat the ends of the push rods using prelube GM P/N 12345501 (Canadian P/N 992704) or equivalent.

3. Important: The intake valve push rods measure 146.0 mm (5.75 inch) and the exhaust valve push rods measure 152.5 mm (6.0 inch).

Install the push rods in their original location.
4. Coat the rocker arm friction surfaces using prelube GM P/N 12345501 (Canadian P/N 992704) or equivalent.

5. Important: Shims (P/N 88894006) may be required under the valve rocker arm pedestals if reconditioning has been performed on the cylinder head or its components.

Install the valve rocker arms in their original positions.

Notice: Refer to Fastener Notice.

6. Install the valve rocker arm bolts.
Tighten the bolts to 34 Nm (25 ft. lbs.).





7. With the NEW gaskets and seals in place, apply a small drop, 8 - 10 mm (0.031 - 0.39 inch) of RTV sealer GM P/N 12378521 (Canadian P/N 88901148) or equivalent to the 4 corners of the intake manifold to engine block joints (1).
8. Install the lower intake manifold.





9. Notice: Maximum gasket performance is achieved when using new fasteners, which contain a thread-locking patch. If the fasteners are not replaced, a thread locking chemical must be applied to the fastener threads. Failure to replace the fasteners or apply a thread-locking chemical MAY reduce gasket sealing capability.

Notice: Failure to tighten vertical bolts before the diagonal bolts may cause an oil leak.

Apply sealer GM P/N 12345382 (Canadian P/N 10953489) or equivalent to the lower intake manifold bolt threads.
10. Install the lower intake manifold bolts.
11. Tighten the lower intake manifold bolts in the sequence shown.
1. Tighten the bolts (1, 2, 3, 4) in sequence to 16 Nm (12 ft. lbs.).
2. Tighten the bolts (5, 6, 7, 8) in sequence to 25 Nm (18 ft. lbs.).





12. Inspect the fuel rail, fuel injectors and fuel injector O-rings for damage and replace as necessary.
13. Lubricate the fuel injector O-rings using GM P/N 12345616 (Canadian P/N 993182).
14. Install the injector nozzles into the lower intake manifold injector bores.
15. Press on the injector rail using the palms of both hands until the injector are fully seated.
16. Install the fuel injector rail bolts.
Tighten the bolts to 10 Nm (89 inch lbs.).
17. Connect the CMP sensor electrical connector.
18. Position the fuel injector harness connector bracket to the intake manifold.
19. Install the fuel injector harness connector bracket bolt.
Tighten the bolt to 8 Nm (71 inch lbs.).





20. Connect the fuel injector inline connector (2).
21. Connect the fuel feed line to the fuel rail.
22. Connect the ECT electrical connector.
23. Install the right valve rocker arm cover.
24. Install the left valve rocker arm cover.
25. Install the upper intake manifold.
26. Install the coolant crossover pipe.