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. Refer to Battery Negative Cable Disconnect/Connect Procedure in Service Precautions.
2. Remove the upper intake manifold. Refer to Intake Manifold Replacement (Upper).
3. Remove the left (front) valve rocker arm cover. Refer to Valve Rocker Arm Cover Replacement (Left Front).
4. Remove the right (rear) valve rocker arm cover. Refer to Valve Rocker Arm Cover Replacement (Right Rear).





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. Remove the fuel pipe clip.





9. Disconnect the fuel feed pipe from the fuel injector rail.





10. Disconnect the fuel return pipe from the fuel injector rail.





11. Remove the fuel injector rail. Refer to Fuel Rail Assembly Replacement in Powertrain Management.
12. Remove the power steering pump from the front engine cover and reposition. Refer to Power Steering Pump Replacement in Steering.





13. Disconnect the heater inlet pipe with heater hose from the lower intake manifold and reposition. Refer to Heater Pipe Replacement-Inlet in Heating and Air Conditioning.
14. Disconnect the radiator inlet hose from the engine. Refer to Radiator Hose Replacement-Inlet in Cooling System.





15. Disconnect the thermostat bypass hose from the thermostat bypass pipe and lower intake manifold pipe.





16. Remove the lower intake manifold bolts.
17. Remove the lower intake manifold.
18. Remove the valve rocker arms and the push rods.





19. Remove the lower intake manifold gaskets and seals.
20. Clean the lower intake manifold gasket and seal surfaces on the cylinder heads and the engine block.
21. Clean the gasket and seal surfaces on the lower intake manifold with degreaser.
22. Remove all the loose RTV sealer.





23. If replacing the lower intake manifold remove the Engine Coolant Temperature (ECT) sensor.





24. If replacing the lower intake manifold, remove the water outlet bolts.
25. Remove the water outlet.





26. If replacing the lower intake manifold, remove the thermostat.

Installation Procedure





1. If removed, install the thermostat.





2. If removed, install the water outlet.

Notice: Refer to Fastener Notice in Service Precautions.

3. Install the water outlet bolts.

Tighten
Tighten the water outlet bolts to 25 Nm (18 ft. lbs.).





4. If removed, install the Engine Coolant Temperature (ECT) sensor.

Tighten
Tighten the coolant temperature sensor to 23 Nm (17 ft. lbs.).





5. Install the lower intake manifold gaskets.
6. With gaskets in place apply 8 - 10 mm (0.31 - 0.39 inch) of RTV Sealer, GM P/N 12346141 or equivalent, to the 4 corners of the intake manifold to block joint (1).
7. Connect the 2 small drops with a bead of RTV Sealer that is between 8 - 10 (0.31 - 0.39) wide and 3.0 - 5.0 mm (0.10 - 0.20 inch) thick (2).
8. Install the push rods and the valve rocker arms.





9. Install the lower intake manifold.

Notice: An oil leak may result if the vertical bolts are not tightened before the diagonal bolts.





10. Install NEW lower intake manifold bolts.

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).






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. Refer to Radiator Hose Replacement-Inlet in Cooling System.





13. Install the heater inlet pipe.
14. Install the heater inlet pipe nut.

Tighten
Tighten the heater inlet pipe nut to (25 Nm (18 lb ft).

15. Install the power steering pump to the front engine cover.





16. Install the fuel injector rail. Refer to Fuel Rail Assembly Replacement in Powertrain Management.

16.1. Install the fuel injector O-rings using GM P/N 12345616 or equivalent.
16.2. Install the injector nozzles into the lower intake manifold injector bores.
16.3. Press on the injector rail using the palms of both hands until the injectors are fully seated.
17. Install the fuel injector rail bolts.

Tighten
Tighten the fuel injector rail bolts to 10 Nm (89 lb in).





18. Connect the fuel return pipe to the fuel injector rail.





19. Connect the fuel feed pipe to the fuel injector rail.





20. Install the fuel feed and return pipe retaining clip.
21. Install the fuel feed and return pipe retaining clip bolt.

Tighten
Tighten the fuel pipe clip bolt to 8 Nm (71 lb in).





22. Install and connect the fuel injector and Manifold Air Pressure (MAP) wiring harness.





23. Connect the Engine Coolant Temperature (ECT) wiring harness.
24. Install the right (rear) valve rocker arm cover. Refer to Valve Rocker Arm Cover Replacement (Right Rear).
25. Install the left (front) valve rocker arm cover. Refer to Valve Rocker Arm Cover Replacement (Left Front).
26. Install the upper intake manifold. Refer to Intake Manifold Replacement (Upper).
27. Connect the battery ground (negative) cable. Refer to Battery Negative Cable Disconnect/Connect Procedure in Service Precautions.