GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C Sierra - 2WD 🢒 Engine 🢒 Engine Mechanical - 4.3L 🢒 Lower Intake Manifold Replacement

Removal Procedure

Important: 

   • The intake manifold may be removed as an assembly. Do not remove the specific intake manifold components unless component service is required.
   • It is not necessary to remove the upper intake manifold in order to remove the lower intake manifold.
   • 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.


    Object Number: 782387 Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  2. Remove the fuel pipes/hoses. Refer to Fuel Hose/Pipes Replacement - Engine Compartment in Engine Controls - 4.3L.
  3. Remove the distributor. Refer to Distributor Replacement in Engine Controls - 4.3L.
  4. Disconnect the evaporative emission (EVAP) canister harness from the purge solenoid valve.

    5. Object Number: 363243 Size: SH
  5. Reposition the heater outlet hose clamp.
  6. Remove the heater outlet hose from the intake manifold.

    7. Object Number: 363246 Size: SH
  7. Reposition the heater inlet hose clamp.
  8. Remove the heater outlet hose clip bolt.
  9. Remove the heater inlet hose from the water pump.
  10. Reposition the heater inlet and outlet hoses.

    11. Object Number: 781993 Size: SH
  11. Disconnect the cruise control cable from the throttle body lever, if equipped.
  12. Remove the cruise control cable from the accelerator control cable bracket, if equipped.

    13. Object Number: 781992 Size: SH
  13. Remove the accelerator cable from the throttle body lever.

    14. Object Number: 781990 Size: SH
  14. Remove the accelerator cable from the accelerator control cable bracket.

    15. Object Number: 782175 Size: SH
  15. Disconnect the following electrical connectors:
    16. • The air conditioning (A/C) compressor clutch (1), if equipped
    • The exhaust gas recirculation (EGR) valve (2)
    • The A/C pressure switch (4), if equipped
  16. Remove the engine wiring harness clip (3) from the accelerator control cable bracket.

    17. Object Number: 398030 Size: SH
  17. Remove the accelerator control cable bracket nuts.
  18. Remove the accelerator control cable bracket with the cables attached, from the throttle body.
  19. Reposition and secure the bracket and cables out of the way.

    20. Object Number: 782174 Size: SH
  20. Disconnect the following electrical connectors:
    21. • The throttle position (TP) sensor (1)
    • The idle air control (IAC) motor (2)
    • The control port injector module (3)
  21. Remove the engine wiring harness clip bolt (4).

    22. Object Number: 782178 Size: SH
  22. Disconnect the following electrical connectors:
    23. • The evaporative emission (EVAP) canister purge solenoid valve (1)
    • The manifold absolute pressure (MAP) sensor (2)

    Object Number: 782180 Size: SH
  23. Remove the engine wiring harness bracket nuts.
  24. Remove the engine wiring harness bracket from the studs.

    25. Object Number: 782177 Size: SH
  25. Remove the engine wiring harness ground nut and ground wire (4) from the rear of the right cylinder head.

    26. Object Number: 782176 Size: SH
  26. Remove the engine wiring harness rear bracket nut at the EVAP canister purge solenoid valve.
  27. Remove the stud holding the engine wiring harness bracket.
  28. Reposition the engine wiring harness with the bracket aside.

    29. Object Number: 781989 Size: SH
  29. Remove the PCV valve hose from the PCV valve cover and the rocker arm cover.

    30. Object Number: 782202 Size: SH
  30. Disconnect the power brake booster vacuum hose from the vacuum fitting (1).

    31. Object Number: 367002 Size: SH
  31. Reposition the radiator inlet hose clamps.
  32. Remove the radiator inlet hose from the thermostat housing.

    33. Object Number: 182853 Size: SH
  33. Reposition the water pump inlet hose clamps.
  34. Remove the water pump inlet hose.

    35. Object Number: 782479 Size: SH
  35. Remove the spark plug wire harness retainer from the EGR valve inlet pipe.

    36. Object Number: 172982 Size: SH
  36. Remove the EGR valve inlet pipe bracket bolt.
  37. Remove the EGR valve inlet pipe.

    38. Object Number: 340090 Size: SH
  38. In order to remove the front intake manifold bolt, perform the following:
    39. 38.1. Remove the drive belt. Refer to Drive Belt Replacement .
    38.2. Loosen the power steering (P/S) pump rear bracket nut.
    38.3. Remove the P/S pump rear bracket front nut.
    38.4. Remove the bolts and the nut for the P/S pump bracket.
    38.5. Leave the A/C compressor, if equipped, and the P/S pump on the bracket.
    38.6. Slide the P/S pump bracket forward to access the front intake manifold bolt.

    Object Number: 31510 Size: SH
  39. Remove the intake manifold - lower bolts.
  40. Remove the intake manifold.
  41. Remove and discard the intake manifold gaskets.
  42. Clean and inspect the intake manifold - lower, if necessary. Refer to Intake Manifold Cleaning and Inspection in Engine Mechanical - 4.3L Unit Repair.

Installation Procedure

Notice: Apply the proper amount of the sealant when assembling this component. Excessive use of the sealant can prohibit the component from sealing properly. A component that is not sealed properly can leak leading to extensive engine damage.


    Object Number: 38512 Size: SH
  1. Apply a 4.0 mm (0.157 in) patch of adhesive GM U.S. P/N 12346141, Canada P/N 10953433, or equivalent to the cylinder head side of the intake manifold gasket at each end.

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

  2. Install the intake manifold gasket onto the cylinder head. Use the gasket locating pins in order to properly seat the gasket.

    3. Object Number: 26744 Size: SH

    Important: The 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 U.S. P/N 12346141, Canada P/N 10953433, or equivalent to the front top of the engine block.
  4. Extend the adhesive bead 13 mm (0.50 in) onto each intake manifold gasket.

    5. Object Number: 26743 Size: SH
  5. Apply a 5 mm (0.197 in) bead of adhesive GM U.S. P/N 12346141, Canada P/N 10953433, or equivalent to the rear top of the engine block.
  6. Extend the adhesive bead 13 mm (0.50 in) onto each intake manifold gasket.

    7. Object Number: 31510 Size: SH
  7. Install the intake manifold.
  8. If reusing the old fasteners, apply threadlock GM U.S. P/N 12345382, Canada P/N 10953489, or equivalent to the threads of the intake manifold - lower bolts.
  9. Install the intake manifold - lower bolts.

    10. Object Number: 188150 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.

    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 intake manifold - lower bolts in sequence shown.

    11. Tighten

    1. Tighten the intake manifold - lower bolts a first pass to 3 N·m (27 lb in).
    2. Tighten the intake manifold - lower bolts a second pass to 12 N·m (106 lb in).
    3. Tighten the intake manifold - lower bolts a final pass to 15 N·m (11 lb ft).

    Object Number: 340090 Size: SH
  11. Slide the P/S pump bracket rearward.
  12. Install the bolts and the nut for the P/S pump bracket.
  13. Install the P/S pump rear bracket front nut.
  14. Tighten the P/S pump rear bracket nut.

    15. Tighten
    Tighten the P/S pump bracket bolts and nuts to 41 N·m (30 lb ft).

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

    16. Object Number: 172982 Size: SH
  16. Install the EGR valve inlet pipe until snug.
  17. Install the EGR valve inlet pipe bracket bolt.

    18. Tighten

        • Tighten the EGR valve inlet pipe fitting to the exhaust manifold to 25 N·m (18 lb ft).
        • Tighten the EGR valve inlet pipe fitting to the intake manifold to 30 N·m (22 lb ft).
        • Tighten the EGR valve inlet pipe bracket bolt to 25 N·m (18 lb ft).

    Object Number: 782479 Size: SH
  18. Install the spark plug wire harness retainer to the EGR valve inlet pipe.

    19. Object Number: 182853 Size: SH
  19. Install the water pump inlet hose.
  20. Position the water pump inlet hose clamps.

    21. Object Number: 367002 Size: SH
  21. Install the radiator inlet hose to the thermostat housing.
  22. Position the radiator inlet hose clamps.

    23. Object Number: 782202 Size: SH
  23. Connect the power brake booster vacuum hose to the vacuum fitting (1).

    24. Object Number: 781989 Size: SH
  24. Install the PCV valve hose to the PCV valve cover and the rocker arm cover.

    25. Object Number: 782176 Size: SH
  25. Position the engine wiring harness and bracket.
  26. Install the engine wiring harness bracket stud.

    27. Tighten
    Tighten the engine wiring harness rear bracket stud to 25 N·m (18 lb ft).

  27. Install the engine wiring harness rear bracket nut at the EVAP canister purge solenoid valve.

    28. Tighten
    Tighten the engine wring harness rear bracket nut to 9 N·m (80 lb in).


    Object Number: 782177 Size: SH
  28. Install the engine wiring harness ground nut and ground wire (4) to the rear of the right cylinder head.

    29. Tighten
    Tighten the engine wiring harness ground nut to 16 N·m (12 lb ft).


    Object Number: 782180 Size: SH
  29. Install the engine wiring harness bracket to the studs.
  30. Install the engine wiring harness bracket nuts.

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


    Object Number: 782387 Size: SH
  31. Connect the EVAP canister harness to the purge solenoid valve.

    32. Object Number: 782178 Size: SH
  32. Connect the following electrical connectors:
    33. • The EVAP canister purge solenoid valve (1)
    • The MAP sensor (2)

    Object Number: 782174 Size: SH
  33. Connect the following electrical connectors:
    34. • The TP sensor (1)
    • The IAC motor (2)
    • The control port injector module (3)
  34. Install the engine wiring harness clip bolt (4).

    35. Tighten
    Tighten the engine wiring harness clip bolt to 9 N·m (80 lb in).


    Object Number: 398030 Size: SH
  35. Position the bracket and cables.
  36. Install the accelerator control cable bracket with the cables attached, to the throttle body.
  37. Install the accelerator control cable bracket nuts.

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


    Object Number: 782175 Size: SH
  38. Connect the following electrical connectors:
    39. • The A/C compressor clutch (1), if equipped
    • The EGR valve (2)
    • The A/C pressure switch (4), if equipped
  39. Install the engine wiring harness clip (3) to the accelerator control cable bracket.

    40. Object Number: 781990 Size: SH
  40. Install the accelerator cable to the accelerator control cable bracket.

    41. Object Number: 781992 Size: SH
  41. Install the accelerator cable to the throttle body lever.

    42. Object Number: 781993 Size: SH
  42. Install the cruise control cable to the accelerator control cable bracket, if equipped.
  43. Connect the cruise control cable to the throttle lever, if equipped.

    44. Object Number: 363246 Size: SH
  44. Position the heater inlet and outlet hoses.
  45. Install the heater inlet hose to the water pump.
  46. Install the heater outlet hose clip bolt.

    47. Tighten
    Tighten the heater outlet hose clip bolt to 25 N·m (18 lb ft).

  47. Position the heater inlet hose clamp.

    48. Object Number: 363243 Size: SH
  48. Install the heater outlet hose to the intake manifold.
  49. Position the heater outlet hose clamp.

    50. Object Number: 782387 Size: SH
  50. Connect the EVAP canister harness to the purge solenoid valve.
  51. Install the fuel pipes/hoses. Refer to Fuel Hose/Pipes Replacement - Engine Compartment in Engine Controls - 4.3L.
  52. Install the distributor. Refer to Distributor Replacement in Engine Controls - 4.3L.
  53. Fill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.