GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 1999 🢒 S/T Isuzu - 2WD 🢒 Engine 🢒 Engine Mechanical - 4.3L 🢒 Intake Manifold Replacement

Intake Manifold Replacement Upper

Removal Procedure
  1. Remove the air cleaner outlet duct from the throttle body. Refer to Air Cleaner Outlet Duct Replacement In Engine Controls.
  2. Remove the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls.

    3. Object Number: 229041 Size: SH
  3. Disconnect the following electrical connectors:
    4. • The A/C pressure switch, if equipped
    • The throttle position (TP) sensor
    • The idle air control (IAC) motor
    • The fuel meter body assembly connector
    • The manifold absolute pressure (MAP) sensor
    • The EVAP canister purge solenoid valve
  4. Remove the EVAP canister purge solenoid valve. Refer to EVAP Canister Purge Solenoid Valve Replacement in Engine Controls.

    5. Object Number: 346148 Size: SH
  5. Disconnect the vacuum hose from the intake manifold, if equipped with A/C.
  6. Remove the vacuum brake booster hose.

    7. Object Number: 172995 Size: SH
  7. Remove the PCV valve hose assembly from the intake manifold and the valve rocker arm cover.

    8. Object Number: 398027 Size: SH
  8. Disconnect the accelerator control cable from the throttle shaft and the accelerator cable bracket. Refer to Accelerator Control Cable Replacement in Engine Controls.
  9. Disconnect the cruise control cable, if equipped from the throttle shaft and the accelerator cable bracket. Refer to Cruise Control Cable Replacement in Cruise Control.
  10. Remove the accelerator cable bracket from the throttle body and the intake manifold.

    11. Object Number: 339439 Size: SH
  11. Remove the accelerator and cruise control cable bracket from the throttle body.

    12. Leave the accelerator and cruise control cables and the engine wiring harness on the bracket.


    Object Number: 339442 Size: SH
  12. Remove the bracket for the engine wiring harness from the intake stud.
  13. Remove the fuel lines from the fuel meter body assembly. Refer to Fuel Hose/Pipes Replacement - Engine Compartment in Engine Controls.

    14. Object Number: 334513 Size: SH
  14. Remove the upper intake manifold. Refer to Intake Manifold Disassemble .
  15. Clean all sealing surfaces. Refer to Intake Manifold Clean and Inspect .

Installation Procedure

    Object Number: 334513 Size: SH
  1. Install the upper intake manifold. Refer to Intake Manifold Assemble .
  2. Install the fuel lines to the fuel meter body assembly. Refer to Fuel Hose/Pipes Replacement - Engine Compartment in Engine Controls.

    3. Object Number: 339442 Size: SH
  3. Install the bracket for the engine wiring harness on the lower intake manifold stud.

    4. 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.

  4. Install the engine wiring harness bracket nut.

    5. Tighten
    Tighten the engine wiring harness bracket nut to 12 N·m (106 lb in).


    Object Number: 339439 Size: SH
  5. Install the accelerator and cruise control cable bracket to the throttle body.
  6. Install the accelerator and cruise control cable bracket nuts.

    7. Tighten
    Tighten the accelerator and cruise control cable bracket nuts to 9 N·m (80 lb in).


    Object Number: 398027 Size: SH
  7. Install the accelerator control cable bracket to the throttle body and the intake manifold.

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

  8. Install the cruise control cable, if equipped to the throttle shaft and the bracket. Refer to Cruise Control Cable Replacement in Cruise Controls.
  9. Install the accelerator control cable to the throttle shaft and the bracket. Refer to Accelerator Control Cable Replacement in Engine Controls.
  10. Install the EVAP canister purge solenoid valve. Refer to EVAP Canister Purge Solenoid Valve Replacement in Engine Controls.

    11. Object Number: 172995 Size: SH
  11. Connect the PCV valve hose assembly to the intake manifold and the valve rocker arm cover.

    12. Object Number: 346148 Size: SH
  12. Connect the vacuum hose to the intake manifold, if equipped with A/C.
  13. Install the vacuum brake booster hose to the intake manifold.

    14. Object Number: 229041 Size: SH
  14. Connect the following electrical connectors:
    15. • The A/C pressure switch, if equipped
    • The throttle position (TP) sensor
    • The idle air control (IAC) motor
    • The fuel meter body assembly connector
    • The manifold absolute pressure (MAP) sensor
    • The EVAP canister purge solenoid valve
  15. Install the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls.
  16. Install the air cleaner outlet duct to the throttle body assembly. Refer to Air Cleaner Outlet Duct Replacement in Engine Controls.

Intake Manifold Replacement Lower

Removal Procedure
  1. Disconnect the battery negative cable. Refer to Battery Replacement in Engine Electrical.
  2. Remove the air cleaner outlet duct from the throttle body. Refer to Air Cleaner Outlet Duct Replacement in Engine Controls.
  3. Remove the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls.

    4. Object Number: 1386 Size: SH
  4. Drain the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  5. Remove the radiator inlet hose at the water outlet.
  6. Remove the heater hose from the intake manifold.
  7. Remove the water pump inlet hose form the intake manifold.

    8. Object Number: 398027 Size: SH
  8. Disconnect the accelerator control cable from the throttle shaft and the accelerator cable bracket. Refer to Accelerator Control Cable Replacement in Engine Controls.
  9. Disconnect the cruise control cable, if equipped from the throttle shaft and the accelerator cable bracket. Refer to Cruise Control Cable Replacement in Cruise Control.
  10. Remove the accelerator cable bracket from the throttle body and the intake manifold.

    11. Object Number: 339439 Size: SH
  11. Remove the accelerator and the cruise control cable bracket from the throttle bracket.

    12. Leave the accelerator and cruise control cables and the wiring harness on the bracket.


    Object Number: 229077 Size: SH
  12. Remove the following electrical connectors:
    13. • The fuel meter body assembly
    • The EVAP canister purge solenoid valve
    • The idle air control (IAC) motor
    • The throttle position (TP) sensor
    • The A/C compressor high pressure switch, if equipped
    • The A/C clutch switch, if equipped
    • The exhaust gas recirculation (EGR) valve
    • The engine coolant temperature (ECT) sensor
    • The ignition coil
    • The ignition control module (ICM)
  13. Remove the engine wiring harness from the retainers.
  14. Move the engine wiring harness aside.
  15. Remove the distributor. Refer to Distributor Replacement in Engine Electrical.

    16. Object Number: 172982 Size: SH
  16. Remove the exhaust gas recirculation (EGR) valve inlet pipe from the intake and exhaust manifold.
  17. Disconnect the fuel supply and return pipes at the rear of the intake manifold. Refer to Fuel Hose/Pipes Replacement - Engine Compartment in Engine Controls.

    18. Object Number: 346148 Size: SH
  18. Disconnect the vacuum hose from the intake manifold, if equipped with A/C.
  19. Disconnect the vacuum brake booster hose

    20. Object Number: 172995 Size: SH
  20. Disconnect the PCV hose assembly from the intake manifold and the valve rocker arm cover.
  21. Remove the EVAP canister purge solenoid valve. Refer to EVAP Canister Purge Solenoid Valve Replacement in Engine Controls.

    22. Object Number: 340090 Size: SH

    Important: Do not discharge the refrigerant.

  22. Perform the following in order to remove the left front bolt for the intake manifold:
    23. 22.1. Remove the drive belt. Refer to Drive Belt Replacement .
    22.2. Loosen the nut for the power steering pump rear bracket at the side of the engine.
    22.3. Remove the secondary air injection (AIR) reactor pipe bracket nut from the power steering pump rear bracket front stud, if equipped.
    22.4. Remove the nut for the power steering pump rear bracket at the front of the engine.
    22.5. Remove the bolts and the nut for the power steering pump mounting bracket.
    22.6. Leave the A/C compressor, if equipped, and the power steering pump on the power steering pump mounting bracket.
    22.7. Slide the power steering pump bracket forward to access the bolt at the front of the intake manifold.

    Object Number: 31510 Size: SH
  23. Remove the lower intake manifold. Refer to Intake Manifold Removal .
  24. Clean all sealing surfaces. Refer to Intake Manifold Clean and Inspect .

Installation Procedure

    Object Number: 31510 Size: SH

    Notice: Proper lower intake manifold fastener tightening sequence and torque is critical. Always follow the tightening sequence, and torque the intake manifold bolts using the 3 step method. Failing to do so may distort the crankshaft bearing bore alignment and cause damage to the crankshaft bearings.

  1. Install the lower intake manifold. Refer to Intake Manifold Installation .

    2. Object Number: 340090 Size: SH
  2. Position the power steering pump mounting bracket.
  3. Loosely install the power steering pump mounting bracket bolts and nuts.

    4. 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.

  4. Install the nut for the power steering pump rear bracket at the front of the engine.

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

  5. Install the AIR reactor pipe bracket nut to the power steering pump rear bracket front stud, if equipped.

    6. Tighten
    Tighten the AIR reactor pipe bracket nut to 41 N·m (30 lb ft).

  6. Install the drive belt. Refer to Drive Belt Replacement .
  7. Install the EVAP canister purge solenoid valve. Refer to EVAP Canister Purge Solenoid Valve Replacement in Engine Controls.

    8. Object Number: 346148 Size: SH
  8. Connect the vacuum brake booster hose.
  9. Connect the vacuum hose to the intake manifold, if equipped with A/C.

    10. Object Number: 172995 Size: SH
  10. Install the PCV hose assembly to the intake manifold and the valve rocker arm cover.
  11. 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.

    12. Object Number: 172982 Size: SH
  12. Install the exhaust gas recirculation (EGR) valve inlet pipe to the intake manifold and the exhaust manifold.

    13. Tighten

    1. Tighten the EGR valve inlet pipe intake manifold nut to 25 N·m (18 lb ft).
    2. Tighten the EGR valve inlet pipe exhaust manifold nut to 30 N·m (22 lb ft).
    3. Tighten the EGR valve inlet pipe clamp bolt to 25 N·m (18 lb ft).

    Object Number: 334551 Size: SH

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

  13. Remove the spark plug for number one cylinder.
  14. Rotate the crankshaft until number one cylinder is in the compression stroke.
  15. Align the two reference marks on the crankshaft balancer (1) and (4) with the two alignment marks (2) and (3) on the front cover.
  16. Install the spark plug. Refer to Spark Plug Replacement in Engine Electrical.
  17. Install the distributor. Refer to Distributor Replacement in Engine Electrical.

    18. Object Number: 229077 Size: SH
  18. Position the engine wiring harness.
  19. Install the engine wiring harness in the retainers.
  20. Install the following electrical connectors:
    21. • The fuel meter body assembly
    • The EVAP canister purge solenoid valve
    • The idle air control (IAC) motor
    • The throttle position (TP) sensor
    • The A/C compressor high pressure switch, if equipped.
    • The A/C compressor clutch switch, if equipped.
    • The exhaust gas recirculation (EGR) valve
    • The engine coolant temperature (ECT) sensor
    • The ignition coil
    • The ignition control module (ICM)

    Object Number: 339439 Size: SH
  21. Install the accelerator cable and cruise control bracket to the throttle body.

    22. Tighten
    Tighten the accelerator cable and cruise control bracket nuts to 9 N·m (80 lb in).


    Object Number: 398027 Size: SH
  22. Install the accelerator cable bracket to the intake manifold and the throttle body.

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

  23. Install the accelerator control cable to the bracket and the throttle shaft. Refer to Accelerator Control Cable Replacement in Engine Controls.
  24. Install the cruise control cable, if equipped to the bracket and the throttle shaft. Refer to Cruise Control Cable Replacement in Cruise Control.

    25. Object Number: 1386 Size: SH
  25. Install the water pump inlet hose to the intake manifold.
  26. Install the heater hose to the intake manifold.
  27. Install the radiator inlet hose to the water outlet. Refer to Radiator Hose Replacement in Engine Cooling.
  28. Fill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  29. Install the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls.
  30. Install the air cleaner outlet duct to the throttle body. Refer to Air Cleaner Outlet Duct Replacement in Engine Controls.
  31. Connect the battery negative cable. Refer to Battery Replacement in Engine Electrical.