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Intake Manifold Replacement - Lower

Intake Manifold Replacement - Lower

Removal Procedure
1. Remove the upper intake manifold.
2. Remove the engine left side valve rocker arm cover.
3. Remove the engine right side valve rocker arm cover.





4. Disconnect the wiring harness from the Engine Coolant Temperature (ECT) sensor.






Important: Use masking tape or another appropriate method in order to identify each fuel injector wiring harness connector cylinder number.

5. Disconnect and remove the fuel injector, Manifold Air Pressure (MAP) and ECT wiring harness.
6. Remove the fuel feed and return pipe from the fuel injector rail.





7. Remove the fuel feed and return pipe retaining clip bolt.
8. Remove the fuel feed and return pipe retaining clip.





9. Remove the fuel injector rail bolts.
10. Remove the fuel injector rail with the fuel injectors.

Important: Do NOT disconnect the power steering pipes or hoses from the power steering pump.

11. Remove the power steering pump from the front engine cover and reposition.
12. Disconnect the heater inlet pipe with heater hose from the lower intake manifold and reposition.
13. Disconnect the inlet radiator hose from the engine.





14. Disconnect the thermostat bypass hose from the lower intake manifold pipe.





15. Remove the lower intake manifold bolts.





16. Remove the lower intake manifold.
17. Loosen the valve rocker arms and remove the push rods.
18. Remove the lower intake manifold gaskets and seals.
19. Clean the lower intake manifold gasket and seal surfaces on the cylinder heads and the engine block.
20. Clean and inspect the lower intake manifold.
21. If you are replacing the lower intake manifold, perform the following steps:
^ Remove the ECT sensor.
^ Remove the thermostat.

Installation Procedure
1. If you are replacing the lower intake manifold, perform the following steps.
^ Install the ECT sensor.
^ Install the thermostat.






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 surfaces.

2. Install the lower intake manifold gaskets.
3. Install the push rods and tighten the valve rocker arms.
4. With the gaskets in place apply a small drop 8-10 mm (0.31-0.39 inch) of RTV sealer GM P/N 12346286 (Canadian P/N 10953472) or equivalent to the 4 corners of the intake manifold to block joint (1).
5. Connect the 2 small drops with a bead of RTV sealer that is between 8-10 mm (0.31-0.39 inch) wide and 3.0-5.0 mm (0.12-0.20 inch) thick (2).
6. Install the lower intake manifold.
7. Apply sealer GM P/N 12345382, (Canadian P/N 10953489) or the equivalent to the lower intake manifold bolt threads.






Notice: Refer to Fastener Notice in Service Precautions.

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.

Important: All lower intake manifold bolts need to be cleaned, free of any foreign material, and reused only if new bolts are unavailable. Use GM P/N 12345382 (Canadian P/N 10953489) or equivalent and apply to the old intake manifold bolt threads.

Important: Manufacturer recommends the center bolts be fully torqued before the diagonal bolts to assure proper seal ability.

Important: Lower intake manifold bolts in location 6 and 7 should be torqued to specification using a crows foot type tool.

8. Install the lower intake manifold bolts.
1. Tighten the lower intake manifold bolts in sequence to 7 Nm (62 inch lbs.) on the first pass.
2. Tighten the lower intake manifold bolts (1, 2, 3, 4) in sequence to 13 Nm (115 inch lbs.) on the final pass.
3. Tighten the lower intake manifold bolts (5, 6, 7, 8) in sequence to 25 Nm (18 ft. lbs.) on the final pass.





9. Connect the thermostat bypass hose to the lower intake manifold pipe.
10. Connect the inlet radiator hose to the engine.
11. Connect the heater inlet pipe to the lower intake manifold.
12. Install the power steering pump to the front engine cover.





13. Install the fuel injector rail.
14. Connect the fuel feed and return pipe to the fuel injector rail.





15. Install the fuel feed and return pipe retaining clip.
16. Install the fuel feed and return pipe retaining clip bolt.
Tighten the fuel feed and return pipe retaining clip bolt to 8 Nm (71 inch lbs.).






Important: The fuel injector wiring harness connectors must be connected to their respective fuel injectors. Failure to connect the fuel injector connectors to their respective fuel injectors may result in excessive exhaust emissions and poor engine performance.

17. Install and connect the fuel injector, MAP and ECT wiring harness.





18. Install the wiring harness to the ECT sensor.
19. Install the engine right side valve rocker arm cover.
20. Install the engine left side valve rocker arm cover.
21. Install the upper intake manifold.