GM Corvette 1984-1996 Repair Guide

Intake Manifold

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REMOVAL & INSTALLATION



5.7L (VIN 8) Engine
1984 vehicles

See Figures 1 and 2

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Disconnect the fuel inlet and return lines.
  6.  
  7. Tag and disconnect the necessary vacuum lines.
  8.  
  9. Label and detach the necessary electrical connections.
  10.  
  11. Disconnect the accelerator, cruise control and detent cables.
  12.  
  13. Disconnect the cable from the accelerator bracket.
  14.  
  15. Remove the intake cover nuts and bolts, then remove the cover.
  16.  
  17. Drain the cooling system into a suitable container.
  18.  
  19. Disconnect the radiator hose from the thermostat outlet and alternator brace.
  20.  
  21. Remove the distributor cap.
  22.  
  23. Matchmark the installed position of the distributor, then remove the distributor from the engine.
  24.  
  25. Disconnect the heater hose from the rear of the intake.
  26.  
  27. Remove the accessory drive belt.
  28.  
  29. Remove the AIR pump pulley.
  30.  
  31. Remove the AIR pump valve adapter, pump mounting bolts, then remove the pump.
  32.  
  33. Detach the coolant temperature sensor electrical connector.
  34.  
  35. Unfasten the intake manifold bolts, then remove the intake manifold.
  36.  
  37. Remove the gasket(s), then thoroughly clean the gasket mating surfaces.
  38.  



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the intake manifold and gaskets, and bolt tightening sequence-1984 5.7L (VIN 8) engine

To install:
  1. Position the gaskets on the cylinder head, with the blocked openings in the gaskets positioned at the rear of the engine.
  2.  
  3. Bend the gasket tab flush with the face of the cylinder head, then apply a 3 / 16 in. (5mm) bead of RTV sealant on the front and rear ridges of the cylinder case.
  4.  
  5. Apply Loctite® 1052624 or equivalent to the manifold mounting bolts.
  6.  
  7. Install the intake manifold mounting bolts and tighten, in the sequence shown in the accompanying figure, to 35 ft. lbs. (47 Nm).
  8.  
  9. The remainder of installation is the reverse of the removal procedure.
  10.  
  11. Tighten the intake cover (TBI assembly) retainers to the specifications shown in the accompanying figure.
  12.  



Click image to see an enlarged view

Fig. Fig. 2: The TBI assembly/intake cover retainers must be tightened to the proper specifications

  1. Connect the negative battery cable.
  2.  
  3. Fill the cooling system with the proper type and amount of coolant.
  4.  

1985-91 Vehicles

See Figures 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13

  1. Disconnect the negative battery cable.
  2.  
  3. Properly relieve the fuel system pressure, as outlined in Fuel System of this repair guide.
  4.  
  5. Drain the engine coolant into a suitable container.
  6.  
  7. Disconnect the throttle and cruise control cables from the throttle body and bracket.
  8.  
  9. If equipped, disconnect the TV cable from the throttle body and bracket.
  10.  
  11. Remove the bracket from the intake plenum.
  12.  
  13. Detach the electrical connectors from the following components:

    Coolant temperature sensor
     
    Throttle Position Sensor (TPS)
     
    Intake Air Temperature (IAT) sensor
     
    Idle Air Control (IAC) valve
     
    Manifold Absolute Pressure (MAP) sensor
     

  14.  
  15. Remove the air intake duct from the throttle body.
  16.  
  17. Tag and disconnect the vacuum hoses from the throttle body and intake plenum.
  18.  
  19. Disconnect the heater hoses from the throttle body.
  20.  
  21. Remove the power brake vacuum booster fitting from the plenum.
  22.  
  23. Unfasten the runner-to-plenum bolts, then remove the plenum from the engine.
  24.  
  25. Detach the vacuum harness from the EGR solenoid.
  26.  
  27. Remove the EGR solenoid from the coolant outlet, then remove the EGR valve from the manifold.
  28.  
  29. Unfasten the injector harness retaining nuts.
  30.  
  31. Remove the runner-to-manifold bolts, then remove the runner.
  32.  
  33. Detach the injector harness connectors.
  34.  
  35. Disconnect the fuel lines, then remove the fuel rail and injector assembly. For more information, please refer to Fuel System of this repair guide.
  36.  
  37. Remove the distributor assembly, as outlined in Engine Electrical of this repair guide.
  38.  



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Fig. Fig. 3: Remove the distributor from the engine



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Fig. Fig. 4: Stuff a rag or shop towel into the distributor hold, to prevent debris from falling into the engine

  1. Remove the AIR pump brace.
  2.  



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Fig. Fig. 5: Remove the retaining bolts, then remove the AIR pump brace

  1. Disconnect the radiator upper hose at the coolant outlet. If necessary, remove the coolant outlet.
  2.  



Click image to see an enlarged view

Fig. Fig. 6: If necessary, unfasten the mounting bolts and remove the coolant outlet

  1. Disconnect the EGR pipe and position it aside.
  2.  



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Fig. Fig. 7: Remove the 2 retaining screws, then position the EGR pipe aside

  1. Disconnect the PCV valve hose and the crankcase vent tube from the manifold.
  2.  
  3. Detach the coolant temperature sensor and temperature switch electrical connectors.
  4.  



Click image to see an enlarged view

Fig. Fig. 8: Unplug the electrical connectors from the coolant temperature switch (1) and sensor (2)

  1. Unfasten the intake manifold mounting bolts, then remove the manifold. If the manifold is stuck on the cylinder block, carefully use a pry tool on the end mounting boss of the manifold only, to pry the manifold up. Never pry under the sides of the manifold!
  2.  



Click image to see an enlarged view

Fig. Fig. 9: If the manifold sticks to the block, carefully use a block of wood and a prytool to carefully pry up on the mounting boss on the end of the manifold

  1. Remove the gasket(s), then thoroughly clean the gasket mating surfaces.
  2.  



Click image to see an enlarged view

Fig. Fig. 10: Remove and discard the intake manifold gaskets

To install:
  1. Position new gaskets on the cylinder head. The coolant passage restrictor in the gaskets must be positioned at the rear of the engine. Bend the gasket tab flush with the front face of the cylinder head.
  2.  
  3. Place a 0.2 in. (5mm) bead of RTV sealant on the front and rear ridges of the cylinder case. Apply a suitable thread locking sealer to the manifold bolts.
  4.  

When installing the manifold, the sealant must still be wet to the touch when installing the bolts.

  1. Position the intake manifold, then install the manifold bolts. Tighten, in the sequences shown in the accompanying figure, to the following specifications:
    1. 1985-88 vehicles: 25-45 ft. lbs. (34-61 Nm).
    2.  
    3. 1989 vehicles: 35 ft. lbs. (47 Nm).
    4.  
    5. 1990-90 vehicles: all bolts except 1 & 4: 35 ft. lbs. (47 Nm). Bolts 1 & 4 to 45 ft. lbs. (61 Nm).
    6.  

  2.  



Click image to see an enlarged view

Fig. Fig. 11: Exploded view of the intake manifold and bolt tightening sequence-1985-88 vehicles



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Fig. Fig. 12: You must tighten the intake manifold bolts in the proper sequence-1989 vehicles



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Fig. Fig. 13: Exploded view of the intake manifold installation and bolt tightening sequence-1990-91 vehicles

  1. Connect the crankcase vent tube and PCV valve hose to the manifold.
  2.  
  3. Install the EGR valve pipe and the AIR pump brace.
  4.  
  5. Connect the radiator upper hose at the coolant outlet.
  6.  
  7. Install the distributor.
  8.  
  9. Install the fuel rail and injector assembly, then connect the fuel lines.
  10.  
  11. Attach the injector harness connectors.
  12.  
  13. Install the runners, gaskets and the runner-to-manifold bolts and tighten to 25 ft. lbs. (34 Nm).
  14.  
  15. Install the injector harness and nuts. Tighten the nuts to 89 inch lbs. (10 Nm).
  16.  
  17. Install the EGR valve to the manifold and tighten the mounting bolts to 12 ft. lbs. (16 Nm).
  18.  
  19. Install the EGR solenoid on the coolant outlet and tighten the coolant outlet bolt to 25 ft. lbs. (34 Nm).
  20.  
  21. Connect the vacuum harness to the EGR solenoid.
  22.  
  23. Install the plenum and runner-to-plenum bolts. Tighten the bolts to 25 ft. lbs. (34 Nm).
  24.  
  25. Connect the power brake vacuum fitting at the plenum. Tighten the fitting to 108 inch lbs. (12 Nm).
  26.  
  27. Attach the heater hoses to the throttle body.
  28.  
  29. Connect all vacuum hoses, as tagged during removal.
  30.  
  31. Install the air intake duct.
  32.  
  33. Attach the electrical connector to the following components:

    Manifold Absolute Pressure (MAP) sensor
     
    Idle Air Control (IAC) valve
     
    Intake Air Temperature (IAT) sensor
     
    Throttle Position Sensor (TPS)
     
    Coolant temperature sensor
     

  34.  
  35. Install the cable bracket to the plenum.
  36.  
  37. If equipped, install the TV cable, to the bracket and throttle body.
  38.  
  39. Connect the throttle and cruise control cables to the bracket and throttle body.
  40.  
  41. Connect the negative battery cable.
  42.  
  43. Fill the cooling system with the proper type and amount of coolant.
  44.  

5.7L (VIN J) Engine

See Figures 14 and 15

These vehicles use an intake plenum instead of a conventional intake manifold assembly.

  1. Disconnect the negative battery cable.
  2.  
  3. Properly relieve the fuel system pressure.
  4.  
  5. Drain the engine coolant into a suitable container.
  6.  
  7. Remove the air intake duct.
  8.  
  9. Unfasten the screws and nuts securing the cable shield and shield.
  10.  
  11. Disconnect the control cable from the throttle body.
  12.  
  13. Unfasten the screws securing the cable hold-down clamps from the plenum.
  14.  
  15. Remove the fresh air hose from the left and right side of the throttle body extension.
  16.  
  17. Tag and detach the electrical connections from the following components:

    Throttle Position Sensor (TPS)
     
    Idle Air Control (IAC) valve
     
    Manifold Air Temperature (MAT)
     

  18.  
  19. Disconnect the coolant bleed hose from the plenum.
  20.  
  21. Detach the power brake booster vacuum hose from the plenum.
  22.  
  23. Disconnect the vacuum hose from between the fuel pressure regulator and plenum.
  24.  
  25. Tag and disconnect vacuum hoses from the mid-plenum; left and right sides.
  26.  
  27. Detach the vacuum hose from the MAP sensor and plenum.
  28.  
  29. Disconnect the fuel lines from the fuel rail.
  30.  
  31. Unfasten the bolts securing the plenum to the injector housing.
  32.  
  33. Detach the electrical connectors from the ignition module.
  34.  
  35. Unplug the electrical connector from the MAP sensor.
  36.  
  37. Remove the purge solenoid/PCV valve hose fitting from the plenum.
  38.  
  39. Tag and detach the purge canister hose connectors.
  40.  
  41. Remove the upper EGR pipe bolts and pipe.
  42.  


WARNING
You must install some type of cover on the intake openings whenever the plenum is removed.

  1. Remove the plenum assembly and gaskets from the vehicle. Cover the injector housing openings with a piece of tape, or something that will keep debris out.
  2.  
  3. If the plenum is being replaced, transfer the following parts to the new plenum:
    1. MAP sensor and bracket; tighten the bracket-to-plenum screws to 89 inch lbs. (10 Nm).
    2.  
    3. Throttle body; tighten the throttle body-to-plenum screws to 19 ft. lbs. (26 Nm).
    4.  
    5. Throttle body extension; tighten the extension-to-plenum screws to 53 inch lbs. (6 Nm).
    6.  
    7. Ignition module; tighten the module-to-plenum screws to 89 inch lbs. (10 Nm).
    8.  

  4.  
  5. Thoroughly clean the injector housing and intake plenum mating surfaces.
  6.  



Click image to see an enlarged view

Fig. Fig. 14: Exploded view of the intake plenum, gaskets and related components-5.7L (VIN J) engines

To install:
  1. Remove the covering or tape from the injector housings.
  2.  
  3. Attach the electrical connectors onto the ignition module.
  4.  
  5. Position the intake plenum, with the MAP sensor, over the fuel pressure regulator.
  6.  
  7. Attach the MAP sensor electrical connector.
  8.  
  9. Connect the vacuum hose to the MAP sensor and plenum.
  10.  

Before securing the plenum to the injector housings, be sure that the remaining vacuum hoses and wiring are accessible.

  1. Position new plenum gaskets, then install the plenum and secure with the retaining bolts. Tighten the bolts, in the sequence shown in the accompanying figure, to 19 ft. lbs. (26 Nm).
  2.  



Click image to see an enlarged view

Fig. Fig. 15: Intake plenum bolt tightening sequence-5.7L (VIN J) engines

  1. Connect the vacuum hoses to the mid-plenum.
  2.  
  3. Attach the fuel lines to the fuel rail and tighten the fittings to 19 ft. lbs. (26 Nm).
  4.  
  5. Connect the vacuum hose between the fuel pressure regulator and plenum.
  6.  
  7. Attach the power brake booster vacuum hose onto the plenum.
  8.  
  9. Fasten the fresh air hose onto the left and right side of the throttle body extension.
  10.  
  11. Install the purge solenoid/PCV valve hose fitting onto the plenum.
  12.  
  13. Connect the rear right side purge canister connection.
  14.  
  15. Attach the electrical connectors to:

    Throttle Position Sensor (TPS)
     
    Idle Air Control (IAC) valve
     
    Manifold Air Temperature (MAT)
     

  16.  
  17. Install the screws securing the cable hold-down clamps onto the plenum and tighten to 18 inch lbs. (2 Nm).
  18.  
  19. Connect the coolant bleed hose onto the plenum.
  20.  
  21. Attach the control cable to the throttle body. Install the cable shield, screws and nuts onto the throttle body. Tighten to 27 inch lbs. (3 Nm).
  22.  
  23. Install the upper EGR pipe and bolts and tighten to 89 inch lbs. (10 Nm).
  24.  
  25. Install the air intake duct.
  26.  
  27. Connect the negative battery cable.
  28.  
  29. Fill the cooling system with the proper type and amount of coolant.
  30.  

5.7L (VIN P and 5) Engines

See Figures 16 and 17

  1. Disconnect the negative battery cable.
  2.  
  3. Properly relieve the fuel system pressure.
  4.  
  5. Drain the engine coolant into a suitable container.
  6.  
  7. Remove the throttle body air duct.
  8.  
  9. Remove the fuel rail covers.
  10.  
  11. Tag and detach the wiring harness connectors from the fuel injectors.
  12.  
  13. Disconnect the left and right wiring harness and position them aside.
  14.  
  15. Remove the accelerator cable bracket bolts/screws, then remove the bracket and cables from the throttle body.
  16.  
  17. Disconnect the secondary air injection diverter valve hoses.
  18.  
  19. Remove the electrical ground strap from the intake manifold assembly.
  20.  
  21. Unfasten the fuel rail bolts/screws, then remove the fuel rail from the manifold and position it aside.
  22.  
  23. Disconnect the vacuum and crankcase vent hoses.
  24.  
  25. Remove the EGR control valve nut, then remove the control valve.
  26.  
  27. Unfasten the emission canister purge control valve bracket nut, then remove the control valve.
  28.  
  29. Unfasten the EGR valve retaining bolts, then remove the EGR valve.
  30.  
  31. Disconnect the secondary air injection pipe from the intake and right exhaust manifold assemblies.
  32.  
  33. Unfasten the retainers, then remove the alternator brace.
  34.  
  35. Disconnect the coolant hoses from the throttle body.
  36.  
  37. Unfasten the retaining bolts/screws then remove the throttle body and gasket.
  38.  
  39. Remove the intake manifold bolts/screw and studs, then remove the intake manifold and gaskets. Discard the gaskets and replace with new ones. Clean the intake manifold retaining bolts/screws and studs. Clean the cylinder head, block and intake manifold mating surfaces.
  40.  



Click image to see an enlarged view

Fig. Fig. 16: Exploded view of the intake manifold

To install:
  1. Apply a 3 / 16 in. (5mm) bead of RTV sealant to the front and rear of the engine block. Extend the bead of sealant 1 / 2 in. (13mm) up each cylinder head assembly to seal and retain the gaskets.
  2.  
  3. Position new gaskets, then install the cylinder head. Install the intake manifold retaining bolts/screw and studs and tighten, in the sequences shown in the accompanying figure, to the following specifications:
    1. Step 1 (all vehicles): tighten all bolts, in sequence, to 71 inch lbs. (8 Nm).
    2.  
    3. Step 2 (1992 vehicles): tighten all bolts, in sequence, to 19 ft. lbs. (26 Nm).
    4.  
    5. Step 2 (1993-96 vehicles): tighten all bolts, in sequence, to 35 ft. lbs. (48 Nm).
    6.  

  4.  



Click image to see an enlarged view

Fig. Fig. 17: The intake manifold bolts must be tightened in the proper sequence

  1. Install the throttle body gasket, and throttle body and secure with the retaining bolts/screws. Tighten to 18 ft. lbs. (25 Nm).
  2.  
  3. Connect the coolant hoses to the throttle body.
  4.  
  5. Install the alternator brace.
  6.  
  7. Install the accelerator cable bracket and cables. Tighten the cable bracket bolts/screw to 89 inch lbs. (10 Nm).
  8.  
  9. Install the secondary air injection pipe fitting. Tighten the air injection pip exhaust manifold fitting to 41 ft. lbs. (55 Nm). Tighten the air injection pipe flange-to-intake manifold bolts/screws to 19 ft. lbs. (26 Nm). Tighten the air injection pipe bracket-to-cylinder head bolt/screw to 25 ft. lbs. (34 Nm).
  10.  
  11. Install the EGR valve assembly and secure with the retaining bolts/screws. Install the EGR control valve and secure with the retaining nut. Tighten the valve bolts/screws and the nut to 18 ft. lbs. (25 Nm).
  12.  
  13. Install the emission canister purge control valve and nut. Tighten the nut to 15 ft. lbs. (20 Nm).
  14.  
  15. Connect the vacuum and crankcase hoses.
  16.  
  17. Install the fuel rail to the manifold. Connect the fuel pressure regulator vacuum tube. Install the fuel rail bolts/screws and tighten to 89 inch lbs. (10 Nm).
  18.  
  19. Attach the electrical ground strap to the intake manifold.
  20.  
  21. Connect the secondary air injection diverter valve hoses.
  22.  
  23. Attach the wiring harness connectors to the fuel injectors. Make sure to match the proper electrical connector with its corresponding cylinder.
  24.  
  25. Connect the throttle body air duct.
  26.  
  27. Install the fuel rail covers.
  28.  
  29. Connect the negative battery cable.
  30.  
  31. Fill the cooling system with the proper type and amount of coolant.
  32.  

 
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