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 or engine performance may be seriously affected. For the correct injector wiring harness connector-to-fuel injector connection procedure, refer to Fuel Injector Replacement .

1. Remove the upper intake manifold. Refer to Upper Intake Manifold Replacement .
2. Remove the right (rear) and left (front) valve rocker arm covers. Refer to Valve Rocker Arm Cover Replacement - Right Side and Valve Rocker Arm Cover Replacement - Left Side .



3. Disconnect the engine coolant temperature (ECT) sensor electrical connector.



4. Remove the fuel injector rail with lines and position aside. Refer to Fuel Injection Fuel Rail Assembly Replacement .
5. Remove the power steering pump from the front engine cover and reposition. Refer to Power Steering Pump Replacement .



6. Disconnect the heater inlet pipe with heater hose from the lower intake manifold and reposition.



7. Remove the lower intake manifold bolts and DISCARD the bolts.
8. Remove the lower intake manifold.



9. Remove rocker arms and push rods. Refer to Valve Rocker Arm and Push Rod Replacement .
10. Remove the lower intake manifold gaskets and seals.



11. If replacing the lower intake manifold remove the ECT sensor.



12. If replacing the lower intake manifold remove the water outlet bolts.
13. Remove the water outlet.



14. If replacing the lower intake manifold remove 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.




1. Install the intake manifold gasket.



2. Install the pushrods.

2.1.	Install the pushrods in their original location.

2.2.	Coat the ends of the pushrods with prelube GM P/N  1052356, or the equivalent.

2.3.	Intake pushrods are 144 mm (5.75 in).

2.4.	Exhaust pushrods are 152.5 mm (6.0 in).

2.5.	Ensure that the pushrods seat in the lifter.

Notice: Refer to Fastener Notice in the Preface section.

3. Install the rocker arm bolts.

Tighten
Tighten the bolts to 14 N·m (124 lb in) +30 degrees.





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.

4. With gaskets in place apply a small drop 8-10 mm (0.31-0.39 in) of RTV sealer GM P/N 12346141 (Canadian P/N 89022195) 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 in) wide and 3.0-5.0 mm (0.12-0.20 in) thick (2).
6. Install the lower intake manifold.




Important: All lower intake manifold bolts need to be cleaned and free of any foreign material, only new bolts are to be used.

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.

7. Install NEW lower intake manifold bolts.

Tighten

1. Tighten the lower intake manifold bolts in sequence to 7 N·m (62 lb in) on the first pass.
2. Tighten the lower intake manifold bolts (1, 2, 3, 4) in sequence to 13 N·m (115 lb in) on the final pass.
3. Tighten the lower intake manifold bolts (5, 6, 7, 8) in sequence to 25 N·m (18 lb ft) on the final pass.
8. Install the thermostat housing. Refer to Engine Coolant Thermostat Housing Replacement .
9. Install the radiator hose to the thermostat housing.



10. Install the heater inlet pipe to the thermostat housing.




Important: Do not press on the fuel pressure regulator valve when installing the fuel injector rail assembly.

11. Install the fuel injector rail assembly.

11.1.

Install the fuel injector O-rings using GM P/N 12345616, (Canadian P/N 993182) or equivalent.

11.2.

Install the injector nozzles into the lower intake manifold injector bores.

11.3.

Press on the injector rail using the palms of both hands until the injectors are fully seated.

12. Install the fuel injector rail bolts.

Tighten
Tighten the fuel injector rail bolts to 10 N·m (89 lb in).




13. Install the fuel feed and return pipe retaining clip.
14. Install the fuel feed and return pipe retaining clip bolt.

Tighten
Tighten the fuel feed and return pipe retaining clip bolt to 8 N·m (71 lb in).




15. Install the upper intake manifold. Refer to Upper Intake Manifold Replacement .
16. Install the valve rocker covers. Refer to Valve Rocker Arm Cover Replacement - Left Side and Valve Rocker Arm Cover Replacement - Right Side .