Lower Intake Manifold Replacement
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. Disconnect the battery ground (negative) cable.
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) wiring harness.
6. Disconnect and remove the fuel injector and manifold air pressure (MAP) wiring harness.
7. Remove the fuel pipe clip bolt.
8. Disconnect the fuel feed pipe from the fuel injector rail.
9. Disconnect the fuel return pipe from the fuel injector rail.
10. Remove the fuel pipe clip.
11. Remove the fuel injector rail.
12. Disconnect the power steering pump from the front engine cover and reposition aside.
13. Disconnect the heater inlet pipe with heater hose from the lower intake manifold and reposition.
14. Disconnect the radiator inlet hose from the engine.
15. Disconnect the thermostat bypass hose from the thermostat bypass pipe and lower intake manifold pipe.
16. Remove the engine coolant temperature (ECT) sensor.
17. Remove the water outlet.
18. Remove the thermostat.
19. Remove the lower intake manifold bolts.
20. Remove the lower intake manifold.
21. Remove the valve rocker arms and pushrods.
22. Remove the lower intake manifold gaskets and seals.
23. Clean the lower intake manifold gasket and seal surfaces on the cylinder heads and the engine block.
24. Clean the gasket and seal surfaces on the lower intake manifold with degreaser.
25. Remove all the loose RTV sealer.
Installation Procedure
1. Install the lower intake manifold gaskets.
2. Install the valve rocker arms and pushrods.
Note: Refer to TSB# 03-06-01-010B (10/24/2003) for updated information about a new intake manifold gasket and installation procedure.
3. Apply sealer GM P/N 12345739 or the equivalent at the engine block-to-lower intake manifold mating surface. Ensure that the bead meets the following conditions:
- 2.0 - 3.0 mm (0.08 - 0.12 inch) wide
- 3.0 - 5.0 mm (0.12 - 0.20 inch) thick
4. Apply sealer GM P/N 12345382 or the equivalent to the lower intake manifold bolt threads.
Notice: Refer to Fastener Notice in Service Precautions.
5. Install the lower intake manifold.
The torque specification is a 2-step process; tighten the vertical lower intake manifold bolts (the four middle ones) to 7 Nm (62 lb in). Tighten the diagonal lower intake manifold bolts (two on each end) to 7 Nm (62 lb in).Tighten the vertical lower intake manifold bolts (the four middle ones) to 13 Nm (115 lb in). Tighten the diagonal lower intake manifold bolts (two on each end) to 25 Nm (18 lb ft).
6. Install the heater inlet pipe.
7. Install the heater inlet pipe nut.
- Tighten the heater inlet pipe nut to 25 Nm (18 lb ft).
8. Install the thermostat.
9. Install the water outlet bolts.
10. Install the engine coolant temperature (ECT) sensor.
- Tighten the engine coolant temperature (ECT) sensor to 23 Nm (17 lb ft).
11. Connect the thermostat bypass hose to the thermostat bypass pipe and lower intake manifold pipe.
12. Connect the radiator inlet hose to the engine.
13. Connect the heater inlet pipe and heater hose to the lower intake manifold.
14. Install the power steering pump to the front engine cover.
15. Install the fuel injector rail.
16. Connect the fuel return pipe to the fuel injector rail.
17. Connect the fuel feed pipe to the fuel injector rail.
18. Install the fuel pipe clip.
19. Install the fuel pipe clip bolt.
- Tighten the fuel pipe clip bolt to 8 Nm (71 lb in).
20. Connect the fuel injector and manifold air pressure (MAP) wiring harness.
21. Connect the engine coolant temperature (ECT) wiring harness.
22. Install the right valve rocker arm cover.
23. Install the left valve rocker arm cover.
24. Install the upper intake manifold.
25. Connect the battery ground (negative) cable.