GM Celebrity/Century/Ciera/6000 1982-1996 Repair Guide

Intake Manifold

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REMOVAL & INSTALLATION




CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

2.2L Engine

See Figure 1

UPPER INTAKE
  1. Disconnect the throttle body from the air cleaner air inlet duct.
  2.  
  3. Remove the accelerator control cable bracket at the manifold and valve cover.
  4.  
  5. Remove the brake vacuum booster hose from the manifold.
  6.  
  7. Disconnect the MAP sensor connection and, then remove the sensor.
  8.  
  9. Disconnect the vacuum harness at the throttle body.
  10.  
  11. Remove the electrical connections at the throttle body and intake manifold.
  12.  
  13. Remove the intake manifold bolts and studs.
  14.  
  15. Remove the manifold and gasket.
  16.  

To install:
  1. Install the manifold and gasket.
  2.  
  3. Install the bolts and studs, tighten to 22 ft. lbs. (30 Nm).
  4.  
  5. Attach the electrical connections to the throttle body and intake manifold.
  6.  
  7. Reinstall the vacuum harness to the throttle body.
  8.  
  9. Install the MAP sensor and connection.
  10.  
  11. Install the brake booster hose to the manifold.
  12.  
  13. Attach the accelerator cable bracket to the manifold and valve cover. Tighten the bolts to 18 ft. lbs. (25 Nm).
  14.  
  15. Install the throttle body to the air cleaner.
  16.  



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the intake manifold assembly used on 2.2L engines

LOWER INTAKE
  1. Disconnect the negative battery cable.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove the air cleaner and duct assembly.
  6.  
  7. Rotate the engine forwards.
  8.  
  9. Disconnect the throttle control cable bracket.
  10.  
  11. Remove the electrical connections from the:

    Throttle body
     
    Fuel injector
     
    Wiring harness clip from under the manifold
     

  12.  
  13. Remove the vacuum hoses from:

    Intake manifold
     
    Plenum
     
    EGR valve
     

  14.  
  15. Remove the power steering pump bracket from the intake manifold brace.
  16.  
  17. Tag and remove the spark plug wires.
  18.  
  19. Relieve the fuel system pressure. This is extremely important.
  20.  
  21. Disconnect the fuel lines, set aside.
  22.  
  23. Remove the transaxle fluid level indicator tube retaining nut, position aside.
  24.  
  25. Remove the nuts and manifold with the plenum attached, then clean all the gasket surfaces on the cylinder head and intake manifold.
  26.  

To install:
  1. Install a new gasket and intake manifold with the plenum attached, then install and tighten the retaining nuts to 24 ft. lbs. (33 Nm).
  2.  
  3. Install the transaxle fluid level indicator tube retaining nut.
  4.  
  5. Attach the fuel lines.
  6.  
  7. Connect the spark plug wires in their proper locations.
  8.  
  9. Attach the power steering pump bracket to the intake manifold brace.
  10.  
  11. Install the vacuum hoses from:

    Intake manifold
     
    Plenum
     
    EGR valve
     

  12.  
  13. Attach the electrical connections to the:

    Throttle body
     
    Fuel injector
     
    Wiring harness clip from under the manifold
     

  14.  
  15. Attach the throttle body cable bracket, then connect the cables to the throttle body.
  16.  
  17. Rotate the engine to it's proper position.
  18.  
  19. Assemble the air cleaner and air duct to the engine.
  20.  
  21. Refill the engine coolant.
  22.  
  23. Connect the negative battery cable, then start the engine, top off the coolant.
  24.  

2.5L Engine

See Figure 2

  1. Relieve the fuel system pressure.
  2.  
  3. Remove the air cleaner and the PCV valve.
  4.  
  5. Drain the cooling system into a clean container.
  6.  
  7. Disconnect the fuel and vacuum lines and the electrical connections at the carburetor/throttle body and manifold.
  8.  



Click image to see an enlarged view

Fig. Fig. 2: Intake manifold assembly used on 2.5L engines

  1. Disconnect the throttle linkage at the EFI unit and disconnect the transaxle downshift linkage and cruise control linkage.
  2.  
  3. Remove the carburetor and the spacer.
  4.  
  5. Remove the bell crank and the throttle linkage. Position to the side for clearance.
  6.  
  7. Remove the heater hose at the intake manifold.
  8.  
  9. Remove the pulse air check valve bracket from the manifold.
  10.  
  11. Remove the manifold attaching bolt and remove the manifold.
  12.  
  13. To install, reverse the removal procedure.
  14.  

2.8L Engine
CARBURETED ENGINE

See Figures 3, 4, 5 and 6

  1. Remove the rocker covers.
  2.  
  3. Drain the cooling system.
  4.  
  5. If equipped, remove the AIR pump and bracket.
  6.  
  7. Remove the distributor cap. Mark the position of the ignition rotor in relation to the distributor body, and remove the distributor. Do not crank the engine with the distributor removed.
  8.  
  9. Remove the heater and radiator hoses from the intake manifold.
  10.  
  11. Remove the power brake vacuum hose.
  12.  
  13. Disconnect and label the vacuum hoses. Remove the EFE pipe from the rear of the manifold.
  14.  
  15. Remove the carburetor linkage. Disconnect and plug the fuel line.
  16.  
  17. Remove the manifold retaining bolts/nuts.
  18.  



Click image to see an enlarged view

Fig. Fig. 3: Use a deep socket to loosen the manifold retainers

  1. Remove the intake manifold. Remove and discard the gaskets, and scrape off the old silicone seal from the front and rear ridges.
  2.  



Click image to see an enlarged view

Fig. Fig. 4: Make sure all wiring and hoses are disconnected before removing the manifold



Click image to see an enlarged view

Fig. Fig. 5: Always discard the old gasket

To install:
  1. The gaskets are marked for right and left side installation; do not interchange them. Clean the sealing surface of the engine block, and apply a 3 / 16 in. (5mm) bead of silicone sealer to each ridge.
  2.  
  3. Install the new gaskets onto the heads. The gaskets will have to be cut slightly to fit past the center pushrods. Do not cut any more material than necessary. Hold the gaskets in place by extending the ridge bead of sealer 1 / 4 in. (6mm) onto the gasket ends.
  4.  
  5. Install the intake manifold. The area between the ridges and the manifold should be completely sealed.
  6.  
  7. Install the retaining bolts and nuts, and tighten in sequence to 23 ft. lbs. (31 Nm). Do not overtighten; the manifold is made from aluminum, and can be warped or cracked with excessive force.
  8.  
  9. The rest of installation is the reverse of removal. Adjust the ignition timing after installation, and check the coolant level after the engine has warmed up.
  10.  



Click image to see an enlarged view

Fig. Fig. 6: Intake manifold tightening sequence for 2.8L engines

FUEL INJECTED ENGINE

See Figure 6

  1. Relieve the pressure in the fuel system before disconnecting any fuel line connections.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the accelerator and TV cable bracket at the intake plenum.
  6.  
  7. Unsecure the throttle body at the intake plenum.
  8.  
  9. Disconnect the EGR valve at the intake plenum.
  10.  
  11. Remove the intake plenum.
  12.  
  13. Unfasten the fuel inlet and return pipes at the fuel rail.
  14.  
  15. Remove the serpentine belt.
  16.  
  17. Remove the power steering pump and lay it aside.
  18.  
  19. Disconnect the alternator and lay it aside.
  20.  
  21. Loosen the alternator bracket.
  22.  
  23. Separate the idle air vacuum hose at the throttle body.
  24.  
  25. Unfasten the wires at the injectors.
  26.  
  27. Remove the fuel rail.
  28.  
  29. Remove the breather tube.
  30.  
  31. Remove both rocker covers.
  32.  
  33. Drain the cooling system.
  34.  
  35. Separate the radiator hose at the thermostat housing.
  36.  
  37. Disconnect the wires at the coolant sensor and the oil sending switch.
  38.  
  39. Remove the coolant sensor.
  40.  
  41. Disconnect the bypass hose at the fill neck and head.
  42.  
  43. Loosen the rocker arms and remove the pushrods.
  44.  
  45. Remove the intake manifold bolts and remove the intake manifold.
  46.  

To install:
  1. Place a 3 / 16 in. (5mm) diameter bead of GM sealer 1052917 or equivalent, on each ridge.
  2.  
  3. Position a new intake manifold gasket.
  4.  
  5. Install the pushrods and tighten the rocker arm nuts to 14-20 ft. lbs. (19-27 Nm).
  6.  
  7. Install the intake manifold and tighten the bolts in sequence.
  8.  
  9. Connect the bypass hose to the filler neck and head.
  10.  
  11. Install the coolant sensor.
  12.  
  13. Attach the wires to the coolant sensor and the oil sending switch.
  14.  
  15. Connect the radiator hose to the thermostat housing.
  16.  
  17. Install both rocker covers.
  18.  
  19. Install the breather tube.
  20.  
  21. Connect the fuel rail.
  22.  
  23. Connect the wires to the injectors.
  24.  
  25. Connect the idle air vacuum hose to the throttle body.
  26.  
  27. Tighten the alternator bracket.
  28.  
  29. Attach the alternator electrical connectors.
  30.  
  31. Install the power steering pump.
  32.  
  33. Install the serpentine belt.
  34.  
  35. Connect the fuel inlet and return pipes to the fuel rail.
  36.  
  37. Install the intake plenum.
  38.  
  39. Attach the EGR valve to the intake plenum.
  40.  
  41. Connect the throttle body to the intake plenum.
  42.  
  43. Connect the accelerator and TV cable bracket to the intake plenum.
  44.  
  45. Connect the negative battery cable.
  46.  
  47. Fill cooling system and check for leaks. Start the engine and allow to come to normal operating temperature. Check for leaks and top off the coolant.
  48.  
  49. Adjust the valves, as required.
  50.  

3.0L Engine

See Figure 7

  1. Relieve the fuel system pressure.
  2.  
  3. Disconnect the battery ground.
  4.  
  5. Drain the cooling system.
  6.  
  7. Remove the air cleaner.
  8.  
  9. Disconnect all hoses and wiring from the manifold.
  10.  
  11. Disconnect the accelerator linkage and cruise control chain.
  12.  

If equipped with an MFI system, remove any component which will interfere with the intake manifold removal.

  1. Disconnect the fuel line.
  2.  
  3. Remove the distributor cap and rotor to remove the Torx® head bolt from the left side of the manifold.
  4.  



Click image to see an enlarged view

Fig. Fig. 7: Intake manifold tightening sequence for 3.0L engines

  1. Unbolt and remove the manifold.
  2.  

To install:
  1. Place a new intake manifold gasket and rubber manifold seals in position at the front and rear rails of the cylinder block. Make sure the pointed end of the seal fits snugly against the block and head.
  2.  
  3. Before installing the intake seals, apply silicone sealer to each ends of the seals.
  4.  
  5. Install the one piece manifold gasket, then carefully set the intake on the engine block.
  6.  
  7. Insert the head to manifold bolts. A new gasket and seals must be used when a manifold is removed.
  8.  
  9. When installing the manifold, start with number 1 and 2 bolts, then gradually tighten both bolts until snug. Continue with the rest of the bolts in sequence, tighten to 41 ft. lbs. (55 Nm).
  10.  
  11. Reverse the removal for installation.
  12.  
  13. Connect the negative battery cable.
  14.  
  15. Close the drain plug and fill the radiator. Start the engine, top off the coolant.
  16.  

3.1L Engine (VIN T)

See Figure 8

  1. Relieve the pressure in the fuel system before disconnecting any fuel line connections.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Separate the accelerator and TV cable bracket at the intake plenum.
  6.  
  7. Disconnect the throttle body at the intake plenum.
  8.  
  9. Remove the EGR valve at the intake plenum.
  10.  
  11. Remove the intake plenum.
  12.  
  13. Detach the fuel inlet and return pipes at the fuel rail.
  14.  
  15. Remove the serpentine belt.
  16.  
  17. Remove the power steering pump and lay it aside.
  18.  
  19. Disconnect the alternator and lay it aside.
  20.  
  21. Loosen the alternator bracket.
  22.  
  23. Unsecure the idle air vacuum hose at the throttle body.
  24.  
  25. Disconnect the wires at the injectors.
  26.  
  27. Separate the fuel rail from the vehicle.
  28.  
  29. Remove the breather tube.
  30.  
  31. Remove both rocker covers.
  32.  
  33. Drain the cooling system.
  34.  
  35. Separate the radiator hose from the thermostat housing.
  36.  
  37. Disconnect the wires at the coolant sensor and the oil sending switch.
  38.  
  39. Remove the coolant sensor.
  40.  
  41. Disconnect the bypass hose at the fill neck and head.
  42.  
  43. Loosen the rocker arms and remove the pushrods.
  44.  
  45. Remove the intake manifold bolts and remove the intake manifold.
  46.  

To install:
  1. Place a 3 / 16 in. (5mm) diameter bead of GM sealer 1052917 or equivalent, on each ridge.
  2.  
  3. Position a new intake manifold gasket.
  4.  
  5. Install the pushrods and tighten the rocker arm nuts to 14-20 ft. lbs. (19-27 Nm).
  6.  
  7. Install the intake manifold and tighten the bolts to specifications.
  8.  
  9. Attach the bypass hose to the filler neck and head.
  10.  
  11. Install the coolant sensor.
  12.  
  13. Connect the wires to the coolant sensor and the oil sending switch.
  14.  
  15. Secure the radiator hose to the thermostat housing.
  16.  
  17. Install both rocker covers.
  18.  
  19. Install the breather tube.
  20.  
  21. Connect the fuel rail.
  22.  
  23. Connect the wires to the injectors.
  24.  
  25. Connect the idle air vacuum hose to the throttle body.
  26.  
  27. Tighten the alternator bracket.
  28.  
  29. Connect the alternator electrical connectors.
  30.  
  31. Install the power steering pump.
  32.  
  33. Install the serpentine belt.
  34.  
  35. Connect the fuel inlet and return pipes to the fuel rail.
  36.  
  37. Install the intake plenum.
  38.  
  39. Connect the EGR valve to the intake plenum.
  40.  
  41. Connect the throttle body to the intake plenum.
  42.  
  43. Connect the accelerator and TV cable bracket to the intake plenum.
  44.  
  45. Connect the negative battery cable.
  46.  
  47. Fill cooling system and check for leaks. Start the engine and allow to come to normal operating temperature. Recheck for leaks, then top-up the coolant.
  48.  
  49. Adjust the valves, as required.
  50.  



Click image to see an enlarged view

Fig. Fig. 8: Tightening sequence for 3.1L engines

3.1L Engine (VIN M)

See Figure 8


CAUTION
The fuel system is under pressure and must be properly relieved before disconnecting the fuel lines. Failure to properly relieve the fuel system pressure can lead to personal injury and component damage.

  1. Relieve the fuel system pressure.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove top half of the air cleaner assembly and throttle body duct.
  6.  
  7. Drain the cooling system.
  8.  
  9. Remove the EGR pipe from exhaust manifold.
  10.  
  11. Remove the serpentine belt.
  12.  
  13. Remove the brake vacuum pipe at the intake plenum.
  14.  
  15. Disconnect the control cables from the throttle body and intake plenum mounting bracket.
  16.  
  17. Remove the power steering lines at the alternator bracket.
  18.  
  19. Remove the alternator.
  20.  
  21. Disconnect the spark plug wires from the spark plugs and wire retainers on the intake plenum.
  22.  
  23. Remove the ignition assembly and the EVAP canister purge solenoid together.
  24.  
  25. Disconnect the upper engine wiring harness connectors at the following components:

    Throttle Position Sensor (TPS)
     
    Idle Air Control (IAC) valve
     
    Fuel Injectors
     
    Coolant temperature sensor
     
    MAP sensor
     
    Camshaft Position (CMP) sensor
     

  26.  
  27. Disconnect the vacuum lines from the following components:

    Vacuum modulator
     
    Fuel pressure regulator
     
    PCV valve
     

  28.  
  29. Remove the MAP sensor from upper intake manifold.
  30.  
  31. Remove the upper intake plenum mounting bolts and remove the plenum.
  32.  
  33. Disconnect the fuel lines from the fuel rail and fuel line bracket.
  34.  
  35. Install engine support fixture special tool J 28467-A or an equivalent.
  36.  
  37. Remove the right side engine mount.
  38.  
  39. Remove the power steering mounting bolts and support the pump out of the way without disconnecting the power steering lines.
  40.  
  41. Disconnect the coolant inlet pipe from coolant outlet housing.
  42.  
  43. Remove the coolant bypass hose from the water pump and the cylinder head.
  44.  
  45. Disconnect the upper radiator hose at thermostat housing.
  46.  
  47. Remove the thermostat housing.
  48.  
  49. Remove both rocker arm covers.
  50.  
  51. Remove the lower intake manifold bolts. Make sure the washers on the four center bolts are installed in their original locations.
  52.  

When removing the valve train components they should be kept in order for installation the original locations.

  1. Remove the rocker arm retaining nuts and remove the rocker arms and pushrods.
  2.  
  3. Remove the intake manifold from the engine.
  4.  

To install:
  1. Clean gasket material from all mating surfaces. Remove all excess RTV sealant from front and rear ridges of cylinder block.
  2.  
  3. Place a 0.1 in. (3mm) bead of RTV, on each ridge, where the front and rear of the intake manifold contact the block.
  4.  
  5. Using a new gasket, install the intake manifold to the engine.
  6.  
  7. Install the pushrods, rocker arms and mounting nuts. Make sure the pushrods are properly seated in the valve lifters and rocker arms.
  8.  
  9. Install rocker arm nuts and tighten the rocker arm nuts to 18 ft. lbs. (24 Nm).
  10.  
  11. Install lower the intake manifold attaching bolts. Apply sealant GM part no. 12345739 or equivalent to the threads of bolts, and tighten bolts to 115 inch lbs. (13 Nm).
  12.  
  13. Install the front rocker arm cover.
  14.  
  15. Install the thermostat housing.
  16.  
  17. Connect the upper radiator hose to the thermostat housing.
  18.  
  19. Install the coolant inlet pipe to thermostat housing.
  20.  
  21. Install coolant bypass pipe at the water pump and cylinder head.
  22.  
  23. Install the power steering pump in the mounting bracket.
  24.  
  25. Connect the right side engine mount.
  26.  
  27. Remove the special engine support tool.
  28.  
  29. Connect the fuel lines to fuel rail and bracket.
  30.  
  31. Install the upper intake manifold and tighten the mounting bolts to 18 ft. lbs. (25 Nm).
  32.  
  33. Install the MAP sensor.
  34.  
  35. Connect the upper engine wiring harness connectors to the following components:

    Throttle Position Sensor (TPS)
     
    Idle Air Control (IAC) valve
     
    Fuel Injectors
     
    Coolant temperature sensor
     
    MAP sensor
     
    Camshaft Position (CMP) sensor
     

  36.  
  37. Connect the vacuum lines to the following components:

    Vacuum modulator
     
    Fuel pressure regulator
     
    PCV valve
     

  38.  
  39. Install the EVAP canister purge solenoid and ignition assembly.
  40.  
  41. Install the alternator assembly.
  42.  
  43. Connect the power steering line to the alternator bracket.
  44.  
  45. Install the serpentine belt.
  46.  
  47. Connect the spark plug wires to the spark plugs and intake plenum wire retainer.
  48.  
  49. Install the EGR pipe to the exhaust manifold.
  50.  
  51. Connect the control cables to the throttle body lever and upper intake plenum mounting bracket.
  52.  
  53. Install air intake assembly and top half of the air cleaner assembly.
  54.  
  55. Install the brake vacuum pipe.
  56.  
  57. Fill the cooling system.
  58.  
  59. Connect the negative battery cable.
  60.  
  61. Start the vehicle and verify no leaks exist.
  62.  

3.3L Engine

See Figure 9

  1. Relieve the pressure in the fuel system before disconnecting any fuel line connections.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Drain the cooling system.
  6.  
  7. Remove the serpentine belt, alternator and braces and power steering pump braces.
  8.  
  9. Remove the coolant bypass hose, heater pipe and upper radiator hose.
  10.  
  11. Remove the air inlet duct, throttle cable bracket and cables.
  12.  
  13. Disconnect and tag all vacuum hoses and electrical connectors, as necessary.
  14.  
  15. Remove the fuel rail, vapor canister purge line and heater hose from the throttle body.
  16.  
  17. Remove the intake manifold retaining bolts and intake manifold.
  18.  

To install:
  1. Clean the cylinder head and intake manifold surfaces from any foreign matter, nicks or heavy scratches.
  2.  
  3. Apply sealer GM part no. 12345336 or equivalent, to the ends of the manifold seals. Clean the intake manifold bolts and bolt holes. Apply thread lock compound GM part no. 1052624 or equivalent, to the intake manifold bolt threads before assembly.
  4.  
  5. Install the new gasket and intake manifold. Tighten the intake manifold bolts twice to 88 inch lbs. (10 Nm) in the proper sequence.
  6.  



Click image to see an enlarged view

Fig. Fig. 9: Intake manifold tightening sequence for 3.3L engines

  1. Install the fuel rail, vapor canister purge line and heater hose from the throttle body.
  2.  
  3. Connect all vacuum hoses and electrical connectors.
  4.  
  5. Install the air inlet duct, throttle cable bracket and cables.
  6.  
  7. Install the coolant bypass hose, heater pipe and upper radiator hose.
  8.  
  9. Install the serpentine belt, alternator and braces and power steering pump braces.
  10.  
  11. Connect the negative battery cable.
  12.  
  13. Fill cooling system and check for leaks. Start the engine and allow to come to normal operating temperature. Recheck for leaks.
  14.  

3.8L Engine

See Figure 10

  1. Relieve the pressure in the fuel system before disconnecting any fuel line connections.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the mass air flow sensor and air intake duct.
  6.  
  7. Remove the serpentine accessory drive belt, alternator and bracket.
  8.  
  9. Remove the ignition coil module, TV cable, throttle cable and cruise control cable.
  10.  
  11. Disconnect and tag all vacuum hoses and electrical wiring, as necessary.
  12.  
  13. Drain the cooling system. Remove the heater hoses from the throttle body and upper radiator hose.
  14.  



Click image to see an enlarged view

Fig. Fig. 10: Intake manifold tightening sequence for 3.8L engines

  1. Disconnect the fuel lines from the fuel rail and injectors.
  2.  
  3. Remove the intake manifold retaining bolts and remove the intake manifold and gasket.
  4.  

To install:
  1. Clean the cylinder head and intake manifold surfaces from any foreign matter, nicks or heavy scratches.
  2.  
  3. Install the intake manifold gasket and rubber seals. Apply sealer GM part no. 1050026 or equivalent, on the gasket. Apply sealer/lubricant GM part no. 1052080 or equivalent, to all pipe thread fitting.
  4.  
  5. Carefully install the intake manifold to cylinder block. Install the intake manifold bolts and tighten in sequence to the specified value.
  6.  
  7. Connect the fuel lines to the fuel rail and injectors.
  8.  
  9. Install the heater hoses to the throttle body and upper radiator hose.
  10.  
  11. Connect all vacuum hoses and electrical wiring.
  12.  
  13. Install the ignition coil module, TV cable, throttle cable and cruise control cable.
  14.  
  15. Install the bracket, alternator and serpentine belt.
  16.  
  17. Install the mass air flow sensor and air intake duct.
  18.  
  19. Connect the negative battery cable.
  20.  
  21. Fill cooling system and check for leaks. Start the engine and allow to come to normal operating temperature. Recheck for leaks.
  22.  

4.3L Diesel Engine

See Figure 11

  1. Remove the air cleaner assembly.
  2.  
  3. Drain the radiator, then disconnect the upper radiator hose from the water outlet.
  4.  
  5. Disconnect the heater inlet hose from the outlet on intake manifold and disconnect the heater outlet pipe from the intake manifold attachments and move it aside.
  6.  
  7. Remove air crossover and the fuel injection pump.
  8.  
  9. Disconnect wiring as necessary at the alternator and air conditioning compressor (if so equipped).
  10.  
  11. Remove the cruise control servo if so equipped.
  12.  
  13. Remove the air conditioning compressor bracket and brace bolts and position the compressor (if so equipped) with lines attached out of the way.
  14.  
  15. Remove the alternator assembly.
  16.  
  17. Disconnect the engine mounting strut.
  18.  
  19. Remove the fuel lines, filter and brackets. Cap all openings.
  20.  
  21. Disconnect the electrical leads to the glow plug controller and sending units.
  22.  
  23. Disconnect the exhaust crossover pipe heat shield.
  24.  
  25. Remove the left (forward) injection lines and cap all openings. Use backup wrench on the nozzles.
  26.  



Click image to see an enlarged view

Fig. Fig. 11: Tightening sequence for the 4.3L engine

  1. Disconnect the throttle and TV cables from the bracket.
  2.  
  3. Remove the drain tube.
  4.  
  5. Remove the intermediate pump adapter.
  6.  
  7. Remove pump adapter and seal.
  8.  
  9. Remove the intake manifold.
  10.  

To install:
  1. Disassemble and bleed-down the lifters. Refer to the procedure earlier in this section.
  2.  
  3. Clean the machined surfaces of cylinder head and intake manifold with a putty knife. Use care not to gouge or scratch the machined surfaces. Clean all bolts and bolt holes.
  4.  
  5. Coat both sides of gasket sealing surface that seal the intake manifold to the head with GM part no. 1050026 sealer or equivalent and position intake manifold gasket. Install end seals, making sure that ends are positioned under the cylinder heads. The seals and mating surfaces must be dry. Any liquid, including sealer will act as a lubricant and cause the seal to move during assembly. Use RTV sealer only on each end of the seal.
  6.  
  7. Position intake manifold on engine. Lubricate the entire intake manifold bolt with lubricant GM part no. 1052080 or equivalent.
  8.  
  9. Tighten the bolts in sequence shown to 20 ft. lbs. (27 Nm). Then retighten to 41 ft. lbs. (56 Nm).
  10.  
  11. Install the drain tube.
  12.  
  13. Install the pump adapter.
  14.  
  15. Apply chassis lube to seal area of intake manifold and pump adapter.
  16.  
  17. Apply chassis lube to inside and outside diameter of seal and seal area of tool J-28425.
  18.  
  19. Install seal on tool and install the seal.
  20.  
  21. Install intermediate pump adapter.
  22.  
  23. Reverse the order of removal and install all other removed parts except the air crossover.
  24.  
  25. Fill the cooling system.
  26.  
  27. Install manifold covers, J-29657.
  28.  
  29. Start engine and check for leaks.
  30.  
  31. Check and if necessary, reset the injection pump timing.
  32.  
  33. Remove screen covers from manifold.
  34.  
  35. Install air crossover.
  36.  
  37. Install the air cleaner.
  38.  
  39. Road test car and inspect for leaks.
  40.  

 
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