Intake Manifold Replacement Upper

1. Carefully disconnect the throttle body air inlet duct.
2. Drain the engine coolant from the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
3. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement .
4. Disconnect the right spark plug wires. Refer to Spark Plug Wire Harness Replacement in Engine Electrical.
5. Disconnect the evaporative emissions canister purge solenoid valve wiring harness connector. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement in Engine Controls - 3.8L.
6. Relieve the fuel pressure. Refer to Fuel Pressure Relief in Engine Controls - 3.8L.
7. Remove the fuel rail. Refer to Fuel Injection Fuel Rail Assembly Replacement in Engine Controls - 3.8L.
8. Remove the brake booster hose from the vacuum source manifold in the upper intake manifold. Refer to Vacuum Brake Booster Hose Replacement in Hydraulic Brakes.



9. Remove the EGR valve wiring harness heat shield nut and bolt and the EGR shield from the upper intake manifold.



10. Remove the throttle body support bracket bolts and the support bracket.



11. Disconnect the MAP sensor electrical connector. Refer to Manifold Absolute Pressure Sensor Replacement in Engine Controls - 3.8L.
12. Remove the upper intake manifold bolts and stud.
13. Clean the upper intake manifold bolt threads.
14. Remove the upper intake manifold.



15. Remove the upper-to-lower intake manifold carrier gasket from the upper intake manifold.
16. If the upper intake manifold is being replaced, remove the throttle body. Refer to Throttle Body Assembly Replacement in Engine Controls - 3.8L.



17. If the upper intake manifold is being replaced, remove the vacuum source manifold.

1. If the upper intake manifold is being replaced, install the vacuum source manifold.
2. If the upper intake manifold is being replaced, install the throttle body. Refer to Throttle Body Assembly Replacement in Engine Controls - 3.8L.



3. Install the upper-to-lower intake manifold carrier gasket to the upper intake manifold.



4. Carefully place the upper intake manifold onto the lower intake manifold. Make sure that the alignment pins in the upper intake manifold align with the holes in the lower intake manifold.
5. Install the upper intake manifold.
6. Apply thread lock compound GM P/N 12345382 or equivalent, to the bolt threads before assembly.




Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

7. Install the upper intake manifold bolts (1-10).

Tighten
Tighten the upper intake manifold bolts in sequence to 10 N·m (89 lb in).

8. Connect the MAP sensor electrical connector. Refer to Manifold Absolute Pressure Sensor Replacement in Engine Controls - 3.8L.



9. Install the throttle body support bracket.
10. Install the throttle body support bracket bolts.

Tighten
Tighten the throttle body support bracket bolts to 10 N·m (89 lb in).




11. Install the EGR shield and the EGR valve wiring harness heat shield nut and bolt to the upper intake manifold.

Tighten
Tighten the EGR valve wiring harness heat shield nut and bolt to 10 N·m (89 lb in).

12. Install the brake booster hose to the vacuum source manifold in the upper intake manifold. Refer to Vacuum Brake Booster Hose Replacement in Hydraulic Brakes.
13. Install the fuel rail. Refer to Fuel Injection Fuel Rail Assembly Replacement in Engine Controls - 3.8L.
14. Connect the evaporative emissions canister purge solenoid valve wiring harness connector. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement in Engine Controls - 3.8L.
15. Install the right (rear) spark plug wires. Refer to Spark Plug Wire Harness Replacement in Engine Electrical.
16. Install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement .
17. Refill the cooling system with engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
18. Carefully install the throttle body air inlet duct.
19. Inspect for the proper fluid levels.
20. Inspect for fluid or vacuum leaks.

Intake Manifold Replacement Lower

Notice: The two bolts which fasten the lower intake manifold to the cylinder head are accessible only after the upper intake is removed. The bolts are located in the right front and left rear corners of the lower intake manifold. Remove the upper intake manifold to service the lower intake.

1. Remove the upper intake manifold. Refer to Intake Manifold Replacement .
2. Remove the generator braces. Refer to Generator Brace Replacement in Engine Electrical.
3. Remove the generator. Refer to Generator Replacement in Engine Electrical.
4. Remove the drive belt tensioner with mounting bracket and the heater water bypass inlet pipe. Refer to Drive Belt Tensioner Replacement .
5. Remove the EGR tube from the lower intake manifold.



6. Remove the radiator inlet hose from the water outlet housing. Refer to Radiator Inlet Hose Replacement in Engine Cooling.



7. Remove the engine coolant temperature (ECT) sensor wiring harness connector.



8. Remove the generator bracket bolts.
9. Remove the generator bracket.
10. Remove the evaporative emissions (EVAP) canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement in Engine Controls - 3.8L.



11. Remove the twelve lower intake manifold bolts.
12. Remove the lower intake manifold.



13. Remove the lower intake manifold seals.



14. Remove the lower intake manifold gaskets.



15. If replacing the lower intake manifold, remove the water outlet housing bolts, water outlet housing, gasket and thermostat.



16. If replacing the lower intake manifold, remove the engine coolant temperature (ECT) sensor.
17. Inspect the flatness of inlet flanges.
18. Clean the engine block.
19. Clean the cylinder block, heads, and the intake manifold sealing surface with a suitable solvent.
20. Clean the intake manifold bolts and bolt holes of adhesive compound.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

1. If removed, install the engine coolant temperature (ECT) sensor. Refer to Engine Coolant Temperature Sensor Replacement in Engine Controls.



2. If removed, install the thermostat, gasket and water outlet housing.
3. Install the water outlet housing bolts.

Tighten
Tighten the water outlet housing bolts to 27 N·m (20 lb ft).




4. Install the lower intake manifold gaskets.



5. Apply sealer GM P/N 12345336 or equivalent to the ends of the intake manifold seals.
6. Install the lower intake manifold seals.



7. Install the lower intake manifold.



8. Install the lower intake manifold bolts (1-12). Apply thread lock compound GM P/N 12345382 or equivalent to the two hidden bolts and ensure they are installed.

Tighten
Tighten the lower intake manifold bolts in sequence to 15 N·m (11 lb ft).




9. Install the generator bracket.
10. Install the generator bracket bolts.

Tighten
Tighten the generator bracket bolts to 50 N·m (37 lb ft).

11. Install the evaporative emissions (EVAP) canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement in Engine Controls - 3.8L.



12. Install the engine coolant temperature (ECT) sensor wiring harness connector.



13. Install the radiator inlet hose to the water outlet housing. Refer to Radiator Inlet Hose Replacement in Engine Cooling.
14. Install the drive belt tensioner mounting bracket and the water heater bypass inlet pipe. Refer to Drive Belt Tensioner Replacement .
15. Install the EGR tube to the lower intake manifold.

Tighten
Tighten the EGR tube bolt to 29 N·m (21 lb ft).

16. Install the generator. Refer to Generator Replacement in Engine Electrical.
17. Install the generator braces. Refer to Generator Brace Replacement in Engine Electrical.
18. Install the upper intake manifold. Refer to Intake Manifold Replacement .