GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Chevy C Pickup - 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 Intake Air Resonator Replacement In Engine Controls.
  2. Disconnect the hose fitting from the EVAP canister purge solenoid valve and move the hose aside.

    3. Object Number: 466638 Size: SH
  3. Disconnect the following electrical connectors:
    4. • 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 engine wiring harness from the engine wiring harness bracket at the right rear of the engine.

    5. Object Number: 466634 Size: SH
  5. Remove the nut and the ground wire from the stud for the engine wiring harness bracket at the rear of the right cylinder head.

    6. Object Number: 466633 Size: SH
  6. Remove the stud at the rear of the right cylinder head and the nut from the EVAP canister purge solenoid valve holding the engine wiring harness bracket.
  7. Remove the engine wiring harness bracket.

    8. Object Number: 466629 Size: SH
  8. Remove the engine wiring harness nut and clip from the throttle body stud.

    9. Object Number: 466731 Size: SH
  9. Remove the engine wiring harness from the engine wiring harness bracket at the left rear of the engine.
  10. Move the engine wiring harness aside.

    11. Object Number: 466729 Size: SH
  11. Remove the bracket for the engine wiring harness from the upper intake studs.

    12. Object Number: 346148 Size: SH
  12. Remove the vacuum brake booster hose.

    13. Object Number: 172995 Size: SH
  13. Remove the PCV valve hose assembly form the intake manifold and the valve rocker arm cover.
  14. Remove the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement in Engine Controls.

    15. Object Number: 398027 Size: SH
  15. Disconnect the accelerator control cable from the throttle shaft and the accelerator cable bracket. Refer to Accelerator Controls Cable Replacement in Engine Controls.
  16. 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.
  17. Remove the accelerator cable bracket from the throttle body and the intake manifold.
  18. Remove the fuel lines from the fuel meter body assembly. Refer to Fuel Hose/Pipes Replacement - Engine Compartment in Engine Controls.

    19. Object Number: 334513 Size: SH
  19. Remove the upper intake manifold. Refer to Intake Manifold Disassemble .
  20. Clean all sealing surfaces. Refer to Intake Manifold Cleaning and Inspection .

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

    4. Object Number: 346148 Size: SH
  4. Install the vacuum brake booster hose to the intake manifold.
  5. Install the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement in Engine Controls.

    6. Object Number: 466729 Size: SH
  6. Install the left side bracket for the engine wiring harness on the lower intake manifold studs.

    7. 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 engine wiring harness bracket nuts.

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


    Object Number: 466731 Size: SH
  8. Install the engine wiring harness to the engine wiring harness bracket at the left rear of the engine.

    9. Object Number: 466629 Size: SH
  9. Install the engine wiring harness clip and nut to the throttle body stud.

    10. Tighten
    Tighten the engine wiring harness clip nut to 10 N·m (88 lb in).


    Object Number: 466633 Size: SH
  10. Install the right side engine wiring harness bracket on the EVAP canister purge solenoid valve stud.
  11. Install the stud and the nut for the engine wiring harness bracket.

    12. Tighten

        • Tighten the engine wiring harness bracket nut to 10 N·m (88 lb in).
        • Tighten the engine wiring harness bracket stud to 25 N·m (18 lb ft).

    Object Number: 466634 Size: SH
  12. Install the ground wire and nut to the engine wiring harness bracket stud at the rear of the right cylinder head.

    13. Tighten
    Tighten the ground wire nut to 8 N·m (71 lb in).


    Object Number: 466638 Size: SH
  13. Install the engine wiring harness to the engine wiring harness bracket at the right rear of the engine.
  14. Connect the following electrical connectors:
    15. • 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 accelerator control cable bracket to the throttle body and the intake manifold.

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

  16. Install the cruise control cable, if equipped to the throttle shaft and the bracket. Refer to Cruise Control Cable Replacement in Cruise Controls.
  17. Install the accelerator control cable to the throttle shaft and the bracket. Refer to Accelerator Controls Cable Replacement in Engine Controls.
  18. Connect the hose fitting for the EVAP canister purge solenoid valve.
  19. Install the air cleaner outlet duct to the throttle body assembly. Refer to Intake Air Resonator 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 Intake Air Resonator Replacement in Engine Controls.
  3. Disconnect the hose fitting from the EVAP canister purge solenoid valve and move the hose aside.

    4. Object Number: 466638 Size: SH
  4. Disconnect the following electrical connectors:
    5. • 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 low pressure cut out switch, if equipped.
    • The A/C clutch switch, if equipped
    • The exhaust gas recirculation (EGR) valve
    • The engine coolant temperature (ECT) sensor
    • The engine coolant temperature (ECT) gauge sensor
    • The ignition coil
    • The ignition control module (ICM)
  5. Remove the engine wiring harness from the engine wiring harness bracket at the right rear of the engine.

    6. Object Number: 466634 Size: SH
  6. Remove the nut and the ground wire from the stud for the engine wiring harness bracket at the rear of the right cylinder head.

    7. Object Number: 466633 Size: SH
  7. Remove the stud at the rear of the right cylinder head and the nut from the EVAP canister purge solenoid valve holding the engine wiring harness bracket.
  8. Remove the engine wiring harness bracket.

    9. Object Number: 466731 Size: SH
  9. Remove the engine wiring harness from the engine wiring harness bracket at the left rear of the engine.

    10. Object Number: 466729 Size: SH
  10. Remove the bracket for the engine wiring harness from the upper intake manifold studs.

    11. Object Number: 466629 Size: SH
  11. Remove the engine wiring harness nut and clip from the throttle body stud.
  12. Remove the nut holding the ground wire to the water outlet.
  13. Move the engine wiring harness aside.
  14. Disconnect the accelerator control cable from the throttle shaft and the accelerator cable bracket. Refer to Accelerator Controls Cable Replacement in Engine Controls.
  15. 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.
  16. Remove the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement in Engine Controls.
  17. Remove the distributor. Refer to Distributor Replacement in Engine Electrical.

    18. Object Number: 71614 Size: SH
  18. Drain the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  19. Remove the outlet heater hose from the intake manifold. Refer to Heater Hoses Replacement in HVAC Systems with A/C - Manual.
  20. Remove the inlet heater hose from the water pump. Refer to Heater Hoses Replacement in HVAC Systems with A/C - Manual.
  21. Remove the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement in Engine Controls.
  22. Remove the water pump inlet hose form the intake manifold.

    23. Object Number: 172982 Size: SH
  23. Remove the spark plug wire harness retainer from the EGR valve inlet pipe.
  24. Remove the exhaust gas recirculation (EGR) valve inlet pipe from the intake and exhaust manifold.
  25. 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.

    26. Object Number: 346148 Size: SH
  26. Disconnect the vacuum brake booster hose

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

    28. Object Number: 340090 Size: SH

    Important: Do not discharge the refrigerant.

  28. Perform the following in order to remove the left front bolt for the intake manifold:
    29. 28.1. Remove the drive belt. Refer to Drive Belt Replacement .
    28.2. Loosen the nut for the power steering pump rear bracket at the side of the engine.
    28.3. Remove the nut for the power steering pump rear bracket at the front of the engine.
    28.4. Remove the bolts and the nut for the power steering pump mounting bracket.
    28.5. Leave the A/C compressor, if equipped, and the power steering pump on the power steering pump mounting bracket.
    28.6. Slide the power steering pump bracket forward to access the bolt at the front of the intake manifold.

    Object Number: 31510 Size: SH
  29. Remove the lower intake manifold. Refer to Intake Manifold Removal .
  30. Clean all sealing surfaces. Refer to Intake Manifold Cleaning and Inspection .

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 nut, and the power steering pump rear bracket nuts to 41 N·m (30 lb ft).

  5. Install the drive belt. Refer to Drive Belt Replacement .

    6. Object Number: 346148 Size: SH
  6. Install the vacuum brake booster hose to the intake manifold.

    7. Object Number: 172995 Size: SH
  7. Install the PCV hose assembly to the intake manifold and the valve rocker arm cover.
  8. 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.

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

    10. 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).
  10. Install the spark plug wire harness retainer on the EGR valve inlet pipe.

    11. 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.

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

    16. Object Number: 71614 Size: SH
  16. Install the water pump inlet hose to the intake manifold.
  17. Install the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement in Engine Controls.
  18. Install the outlet heater hose to the intake manifold. Refer to Heater Hoses Replacement in HVAC Systems with A/C - Manual.
  19. Install the inlet heater hose to the water pump. Refer to Heater Hoses Replacement in HVAC Systems with A/C - Manual.
  20. Fill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  21. Install the accelerator control cable to the bracket and the throttle shaft. Refer to Accelerator Controls Cable Replacement in Engine Controls.
  22. Install the cruise control cable, if equipped to the bracket and the throttle shaft. Refer to Cruise Control Cable Replacement in Cruise Control.

    23. Object Number: 466729 Size: SH
  23. Install the left side bracket for the engine wiring harness on the lower intake manifold studs.
  24. Install the engine wiring harness bracket nuts.

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


    Object Number: 466731 Size: SH
  25. Install the engine wiring harness to the engine wiring harness bracket at the left rear of the engine.

    26. Object Number: 466633 Size: SH
  26. Install the right side engine wiring harness bracket on the EVAP canister purge solenoid valve stud.
  27. Install the stud and the nut for the engine wiring harness bracket.

    28. Tighten

        • Tighten the engine wiring harness bracket nut to 10 N·m (88 lb in).
        • Tighten the engine wiring harness bracket stud to 25 N·m (18 lb ft).

    Object Number: 466634 Size: SH
  28. Install the ground wire and nut to the engine wiring harness bracket stud at the rear of the right cylinder head.

    29. Tighten
    Tighten the ground wire nut to 8 N·m (71 lb in).


    Object Number: 466638 Size: SH
  29. Install the engine wiring harness to the engine wiring harness bracket at the right rear of the engine.
  30. Connect the following electrical connectors:
    31. • 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 low pressure cut out switch, if equipped.
    • The A/C clutch switch, if equipped
    • The exhaust gas recirculation (EGR) valve
    • The engine coolant temperature (ECT) sensor
    • The engine coolant temperature (ECT) gauge sensor
    • The ignition coil
    • The ignition control module (ICM)

    Object Number: 466629 Size: SH
  31. Install the engine wiring harness clip and nut to the throttle body stud.

    32. Tighten
    Tighten the engine wiring harness clip nut to 10 N·m (88 lb in).

  32. Install the ground wire and nut on the stud for the water outlet.

    33. Tighten
    Tighten the ground wire nut to 8 N·m (71 lb in).

  33. Connect the hose fitting for the EVAP canister purge solenoid valve.
  34. Install the air cleaner outlet duct to the throttle body. Refer to Intake Air Resonator Replacement in Engine Controls.
  35. Connect the battery negative cable. Refer to Battery Replacement in Engine Electrical.