Important: You do not have to remove the upper intake manifold in order to remove the lower intake manifold.

1. Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
2. Remove the engine cover. Refer to Engine Cover Replacement in Interior Trim.
3. Drain the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.



4. Remove the retaining nut (1) from the air cleaner outlet .
5. Remove the air cleaner outlet duct (2) from the throttle body assembly.



6. Disconnect the harness connector of the intake air temperature (IAT) sensor .



7. Loosen the air cleaner outlet duct from the mass air flow (MAF) sensor.
8. Remove the air cleaner outlet duct.
9. Remove the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls - 4.3L.
10. Disconnect the accelerator control cable from the throttle shaft and the accelerator control cable bracket. Refer to Accelerator Control Cable Replacement in Engine Controls - 4.3L.
11. Disconnect the cruise control cable, if equipped from the throttle shaft and the accelerator control cable bracket. Refer to Cruise Control Cable Replacement in Cruise Control.



12. Disconnect the PCV valve hose assembly from the intake manifold and the valve rocker arm cover.



13. Disconnect the following electrical connectors:

•	The throttle position (TP) sensor (1)

•	The idle air control (IAC) motor (2)

•	The engine coolant temperature (ECT) gauge sensor (3)

•	The A/C high pressure switch (4), if equipped




14. Disconnect the following electrical connectors:

•	The fuel meter body assembly connector (1)

•	The EVAP canister purge solenoid valve (2)

•	The manifold absolute pressure (MAP) sensor (3)




15. Disconnect the following electrical connectors:

•	The A/C compressor clutch (1), if equipped

•	The EGR valve (2)

•	The engine coolant temperature (ECT) sensor (3)

16. Remove the ground wire (4) from the stud at the water outlet.



17. Remove the radiator inlet hose at the water outlet. Refer to Radiator Inlet Hose Replacement in Engine Cooling.
18. Remove the heater hose from the intake manifold. Refer to Heater Inlet Hose Replacement and Heater Outlet Hose Replacement in Heating, Ventilation and Air Conditioning.
19. Remove the water pump inlet hose from the intake manifold.



20. Disconnect the A/C vacuum hose from the intake manifold.
21. Disconnect the power brake booster vacuum hose from the intake manifold.
22. Remove the power brake booster vacuum hose bracket and nut.



23. Remove the accelerator control cable bracket from the throttle body and the intake manifold.
24. Remove the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement in Engine Controls - 4.3L.
25. Remove the distributor. Refer to Distributor Replacement in Engine Controls - 4.3L.
26. Disconnect the fuel supply and the return pipes at the rear of the intake manifold. Refer to Fuel Hose/Pipes Replacement - Engine Compartment in Engine Controls - 4.3L.
27. Remove the ignition control module (ICM). Refer to Ignition Control Module Replacement in Engine Controls - 4.3L.



28. Remove the spark plug wire harness retainer from the exhaust gas recirculation (EGR) valve inlet pipe.
29. Remove the clamp bolt for the EGR valve inlet pipe.
30. Remove the EGR valve inlet pipe from the intake and the exhaust manifolds.



31. In order to remove the front intake manifold bolt, perform the following:

31.1.

Remove the auxiliary evaporator tube from the A/C compressor, if equipped. Refer to Auxiliary Air Conditioning Evaporator Tube Replacement in Heating, Ventilation and Air Conditioning.

31.2.

Remove the drive belt. Refer to Drive Belt Replacement .

31.3.

Loosen the nut for the power steering pump rear bracket.

31.4.

Remove the bolts and the nut for the power steering pump mounting bracket.

31.5.

Leave the A/C compressor, if equipped, and the power steering pump on the bracket.

31.6.

Slide the power steering pump bracket forward to access the bolt at the front of the intake manifold.




32. Remove the engine coolant temperature (ECT) sensor wire connector (if equipped) from the engine wiring harness bracket.
33. Remove the lower intake manifold bolts.

Important: The intake manifold may be removed as an assembly. Do not remove the specific intake manifold components unless component service is required.

Do not allow dirt or debris to enter the fuel system. Ensure that the ends of the fuel system are properly sealed.
Do not disassemble the Central Sequential Fuel Injection (SFI) unit, unless service is required.
34. Remove the intake manifold assembly.
35. Remove and discard the lower intake manifold gaskets.
36. Clean all sealing surfaces and the intake manifold. Refer to Intake Manifold Cleaning and Inspection in Engine Unit Repair.
37. If the intake manifold requires replacement refer to Intake Manifold Disassemble and Intake Manifold Assemble in Engine Unit Repair.

1. Apply a 4.0 mm (0.157 in) patch of adhesive GM P/N 12346141 or equivalent to the cylinder head side of the lower intake manifold gasket at each end.

Important: The lower intake manifold gasket must be installed while the adhesive is still wet to the touch.

2. Install the lower intake manifold gasket onto the cylinder head.

Use the gasket locator pins in order to properly seat the lower intake manifold gasket on the cylinder head.





Important: The lower intake manifold must be installed and the fasteners tightened while the adhesive is still wet to the touch.

3. Apply a 5 mm (0.197 in) bead of adhesive GM P/N 12346141 or equivalent to the front top of the engine block.
4. Extend the adhesive bead 13 mm (0.50 in) onto each lower intake manifold gasket.



5. Apply a 5 mm (0.197 in) bead of adhesive GM P/N 12346141 or equivalent to the rear top of the engine block.
6. Extend the adhesive bead 13 mm (0.50 in) onto each lower intake manifold gasket.



7. Install the lower intake manifold onto the engine block.
8. If reusing the fasteners, apply threadlock GM P/N 12345382 or equivalent to the threads of the lower intake manifold bolts.
9. Install the lower intake manifold bolts.




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.

10. Tighten the lower intake manifold bolts.

Tighten

1. Tighten the bolts on the first pass in sequence (1-8) to 3 N·m (27 lb in).
2. Tighten the bolts on the second pass in sequence (1-8) to 12 N·m (106 lb in).
3. Tighten the bolts on the final pass in sequence (1-8) to 15 N·m (11 lb ft).



11. Reposition the power steering pump mounting bracket.
12. Install the power steering pump mounting bracket three bolts and the nut.

Tighten
Tighten the power steering pump mounting bracket bolts and the nut and the power steering pump rear bracket nut to 41 N·m (30 lb ft).

13. Install the drive belt. Refer to Drive Belt Replacement .
14. Install the auxiliary evaporator tube to the A/C compressor, if equipped. Refer to Auxiliary Air Conditioning Evaporator Tube Replacement in Heating, Ventilation and Air Conditioning.
15. Install the exhaust gas recirculation (EGR) valve inlet pipe to the intake and the exhaust manifolds. Refer to Exhaust Gas Recirculation Pipe Replacement in Engine Controls - 4.3L.
16. Install the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement in Engine Controls - 4.3L.
17. Install the fuel supply and return pipes to the rear of the intake manifold. Refer to Fuel Hose/Pipes Replacement - Engine Compartment in Engine Controls - 4.3L.




Important: In order to install the distributor for the correct engine timing, position the engine to number one cylinder top dead center.

18. Remove the spark plug for number one cylinder.
19. Rotate the crankshaft until number one cylinder is in the compression stroke.
20. Align the two reference marks on the crankshaft balancer (1) and (4) with the two alignment marks (2) and (3) on the front cover.
21. Install the spark plug. Refer to Spark Plug Replacement in Engine Controls - 4.3L.
22. Install the distributor. Refer to Distributor Replacement in Engine Controls - 4.3L.
23. Install the ICM. Refer to Ignition Control Module Replacement in Engine Controls - 4.3L.



24. Install the accelerator control cable bracket, studs, and nuts to the intake manifold and the throttle body.

Tighten
Tighten the accelerator control cable bracket nuts and studs to 12 N·m (106 lb in).




25. Install the power brake booster vacuum hose bracket to the intake manifold stud.

Tighten
Tighten the bracket nut to 11 N·m (97 lb in).

26. Connect the power brake booster vacuum hose to the intake manifold.
27. Install the A/C vacuum hose to the intake manifold.



28. Install the water pump inlet hose to the intake manifold.
29. Install the heater hoses. Refer to Heater Inlet Hose Replacement and Heater Outlet Hose Replacement in Heating, Ventilation and Air Conditioning.
30. Install the radiator inlet hose to the water outlet. Refer to Radiator Inlet Hose Replacement in Engine Cooling.



31. Connect the following electrical connectors:

•	The throttle position (TP) sensor (1)

•	The idle air control (IAC) motor (2)

•	The engine coolant temperature (ECT) gauge sensor (3)

•	The A/C high pressure switch (4), if equipped




32. Connect the following electrical connectors:

•	The fuel meter body assembly connector (1)

•	The EVAP canister purge solenoid valve (2)

•	The manifold absolute pressure (MAP) sensor (3)




33. Connect the following electrical connectors:

•	The A/C compressor clutch (1), if equipped

•	The EGR valve (2)

•	The engine coolant temperature (ECT) sensor (3)

34. Install the ground wire (4) and the nut to the water outlet stud.

Tighten
Tighten the ground wire nut to 10 N·m (88 lb in).




35. Install the PCV valve hose assembly to the intake manifold and the valve rocker arm cover.
36. Install the cruise control cable, if equipped to the throttle shaft and the accelerator control cable bracket. Refer to Cruise Control Cable Replacement in Cruise Control.
37. Install the accelerator control cable to the throttle shaft and the accelerator control cable bracket. Refer to Accelerator Control Cable Replacement in Engine Controls - 4.3L.
38. Refill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.




Notice: 

•	Handle the MAF sensor carefully.

•	Do not drop the MAF sensor in order to prevent damage to the MAF sensor.

•	Do not damage the screen located on the air inlet end of the MAF.

•	Do not touch the sensing elements.

•	Do not allow solvents and lubricants to come in contact with the sensing elements.

•	Use a small amount of a soap based solution in order to aid in the installation.

39. Install the air cleaner outlet duct to the MAF sensor.



40. Connect the IAT sensor harness connector.



41. Install the air cleaner outlet duct (2) on the throttle body assembly.
42. Tighten the retaining nut (1).

Tighten
Tighten the nut 2 N·m (18 lb in).

43. Install the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls - 4.3L.
44. Connect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
45. Install the engine cover. Refer to Engine Cover Replacement in Interior Trim.