GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Intake Manifold

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11

Buick Built V6
  1. Disconnect the battery, remove the air cleaner and drain the radiator.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the 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.

  1. Disconnect the following:
    1. The upper radiator hose and coolant bypass hose at the manifold. If the dipstick tube connects to the alternator adjusting brace, remove it, also, at this time.
    2.  
    3. The alternator upper bracket, on 1986-87 models.
    4.  
    5. Accelerator downshift and/or throttle valve cable(s) and bracket at the manifold.
    6.  
    7. Booster vacuum pipe at the manifold.
    8.  
    9. The EFE valve vacuum line at the manifold, if so equipped.
    10.  
    11. Carburetor fuel line and choke pipes.
    12.  
    13. Automatic transmission vacuum modulator line.
    14.  
    15. Idle stop solenoid wire or idle Speed Control wiring.
    16.  
    17. Distributor primary wires and the temperature sending unit wires.
    18.  
    19. Any remaining vacuum hoses. On 1983 Olds, remove the A/C top bracket, if so equipped. On 1986-90 models, remove the air conditioner compressor brace and disconnect the bracket at the manifold.
    20.  

  2.  
  3. Remove the distributor cap and rotor for access to the left side manifold head bolt that is a Torx® type bolt on engines built before 1986. On 1986-87 models, remove the distributor and, if there is a separate coil, the coil as well.
  4.  
  5. Remove the plug wires and accelerator linkage springs.
  6.  
  7. Remove the manifold bolts. The Torx® bolt may be removed with a No. 45 Torx® socket. Remove the manifold.
  8.  

To install:
  1. Clean all gasket surfaces with a gasket scraper and solvent.
  2.  
  3. Place a new gasket and rubber seals in position at the front and rear rail of the block. Make sure the pointed end of the seal fits snugly against both the block and head. Coat both ends of these seals with Room Temperature Vulcanizing (RTV) sealant.
  4.  
  5. With an assistant, carefully position the manifold over the seals and gasket so that the seals and gasket remain in proper position.
  6.  


WARNING
DO NOT slide the manifold into position if the bolts will not line up. This may cause the gasket to become dislodged. With an assistant, remove the manifold, reposition the gasket and try again until the manifold bolts will thread.

  1. Start the manifold bolts.
  2.  
  3. Using the proper tightening sequence, tighten the No. 1 and No. 2 bolts first until snug. Then, continue with the rest of the bolts in sequence until all are just snug. Finally, torque in sequence to 45 ft. lbs. (61 Nm).
  4.  
  5. Install the plug wires and accelerator linkage springs.
  6.  
  7. Install the distributor, cap and rotor, if removed. Adjust the timing after all components have been installed.
  8.  
  9. Install any remaining vacuum hoses. On 1983 Olds, install the A/C top bracket, if so equipped. On 1986-87 models, install the air conditioner compressor brace and connect the bracket at the manifold.
  10.  
  11. Install the distributor primary wires and the temperature sending unit wires.
  12.  
  13. Connect the idle stop solenoid wire or idle Speed Control wiring.
  14.  
  15. Connect the automatic transmission vacuum modulator line.
  16.  
  17. Connect the carburetor fuel line and choke pipes.
  18.  
  19. Connect the EFE valve vacuum line at the manifold, if so equipped.
  20.  
  21. Connect the booster vacuum pipe at the manifold.
  22.  
  23. Install the accelerator downshift and/or throttle valve cable(s) and bracket at the manifold.
  24.  
  25. Install the alternator upper bracket, on 1986-87 models.
  26.  
  27. Install the upper radiator hose and coolant bypass hose at the manifold. If the dipstick tube connects to the alternator adjusting brace, install it, also, at this time.
  28.  
  29. Connect the battery, install the air cleaner and refill the radiator with engine coolant.
  30.  
  31. Start the engine and check for leaks. Adjust the timing at this time.
  32.  



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Fig. Fig. 1: Exploded view of a common intake manifold assembly



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Fig. Fig. 2: Buick V6 intake manifold tightening sequence



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Fig. Fig. 3: Buick V8 intake manifold tightening sequence

All Other Engines Except Diesel
  1. Disconnect the negative battery cable and drain the cooling system.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the 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.

  1. Remove the air cleaner assembly.
  2.  
  3. Remove the thermostat housing and the bypass hose. It is not necessary to disconnect the top radiator hose at the thermostat housing.
  4.  
  5. Disconnect the heater hose at the rear of the manifold.
  6.  
  7. Disconnect all electrical connections and vacuum lines from the manifold. Remove the EGR valve if necessary.
  8.  
  9. On vehicles equipped with power brakes remove the vacuum line from the vacuum booster to the manifold.
  10.  
  11. Mark rotor and distributor housing-to-block locations. Remove the distributor (if necessary).
  12.  
  13. Remove the fuel line(s) to the carburetor or the throttle body.
  14.  
  15. Remove and label the carburetor or throttle body linkage and electrical connections.
  16.  
  17. Remove the carburetor or throttle body.
  18.  
  19. Remove the intake manifold bolts. Remove the manifold and the gaskets. Remember to reinstall the O-ring seal between the intake manifold and timing chain cover during assembly, if so equipped.
  20.  

To install:
  1. Clean all gasket mating surfaces with a gasket scraper and solvent.
  2.  

Use care not to damage aluminum engine parts during gasket removal.

Use plastic gasket retainers to prevent the manifold gasket from slipping out of place, if so equipped.

  1. Install the intake manifold gaskets. Remember to reinstall the O-ring seal between the intake manifold and timing chain cover during assembly, if so equipped. With an assistant, carefully position the manifold onto the engine.
  2.  


WARNING
DO NOT slide the manifold into position if the bolts will not line up. This may cause the gasket to become dislodged. With an assistant, remove the manifold, reposition the gasket and try again until the manifold bolts will thread.

  1. Torque the intake manifold in the proper tightening sequence and to the proper torque.
  2.  
  3. Install the carburetor or throttle body.
  4.  
  5. Install the carburetor or throttle body linkage and reconnect the electrical connections.
  6.  
  7. Install the fuel line(s) to the carburetor or throttle body.
  8.  
  9. Install the distributor at the housing-to-block and rotor locations. Install the distributor (if removed).
  10.  
  11. On vehicles equipped with power brakes install the vacuum line from the vacuum booster to the manifold.
  12.  
  13. Connect all electrical connections and vacuum lines to the manifold. Install the EGR valve if necessary.
  14.  
  15. Connect the heater hose at the rear of the manifold.
  16.  
  17. Install the thermostat housing and the bypass hose.
  18.  
  19. Install the air cleaner assembly.
  20.  
  21. Connect the negative battery cable and refill the cooling system.
  22.  
  23. Start the engine and check for oil, vacuum, coolant and fuel leaks.
  24.  



Click image to see an enlarged view

Fig. Fig. 4: Oldsmobile V8 intake manifold tightening sequence; gasoline shown



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Fig. Fig. 5: Chevrolet V8 intake manifold tightening sequence



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Fig. Fig. 6: Chevrolet V6 intake manifold tightening sequence

Diesel Engines
  1. Remove the air cleaner.
  2.  
  3. Drain the radiator. Loosen the upper bypass hose clamp, remove the thermostat housing bolts, and remove the housing and the thermostat from the intake manifold.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the 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.

  1. Remove the breather pipes from the rocker covers and the air crossover. Remove the air crossover.
  2.  
  3. Disconnect the throttle rod and the return spring. If equipped with cruise control, remove the servo.
  4.  
  5. Remove the hairpin clip at the bellcrank and disconnect the cables. Remove the throttle cable from the bracket on the manifold; position the cable away from the engine. Disconnect and label any wiring as necessary.
  6.  
  7. Remove the alternator bracket if necessary. If equipped with air conditioning, remove the compressor mounting bolts and move the compressor aside, without disconnecting any of the hoses. Remove the compressor mounting bracket from the intake manifold.
  8.  
  9. Disconnect the fuel line from the pump and the fuel filter. Remove the fuel filter and bracket.
  10.  
  11. Remove the fuel injection pump and lines.
  12.  
  13. Disconnect and remove the vacuum pump or oil pump drive assembly from the rear of the engine.
  14.  
  15. Remove the intake manifold drain tube.
  16.  
  17. Remove the intake manifold bolts and remove the manifold. Remove the adapter seal. Remove the injection pump adapter.
  18.  

To install:
  1. Clean the mating surfaces of the cylinder heads and the intake manifold using a gasket scraper and solvent.
  2.  
  3. Coat both sides of the gasket surface that seal the intake manifold to the cylinder heads with G.M. sealer #1050026 or the equivalent.
  4.  


WARNING
DO NOT slide the manifold into position if the bolts will not line up. This may cause the gasket to become dislodged. With an assistant, remove the manifold, reposition the gasket and try again until the manifold bolts will thread.

  1. With an assistant, position the intake manifold gaskets on the cylinder heads. Install the end seals, making sure that the ends are positioned under the cylinder heads.
  2.  
  3. Carefully lower the intake manifold into place on the engine.
  4.  
  5. Clean the intake manifold bolts thoroughly, then dip them in clean engine oil. Install the bolts and torque to 15 ft. lbs. (20 Nm) in the proper sequence. Next, torque all the bolts to 30 ft. lbs. (41 Nm), in sequence, and finally tighten to 40 ft. lbs. (54 Nm) in sequence.
  6.  
  7. Install the intake manifold drain tube and clamp.
  8.  
  9. Install injection pump adapter. Make sure not to run the engine without the vacuum pump in place as this drives the oil pump.
  10.  
  11. Install the fuel injection pump and lines.
  12.  
  13. Connect the fuel line to the pump and the fuel filter. Install the fuel filter and bracket.
  14.  
  15. Install the alternator bracket if removed. If equipped with air conditioning, install the compressor bracket and compressor. Install the compressor mounting bracket bolts to the intake manifold.
  16.  
  17. Install the hairpin clip to the bellcrank and connect the cables. Install the throttle cable to the bracket on the manifold.
  18.  
  19. Connect any wiring as necessary.
  20.  
  21. Connect the throttle rod and the return spring. If equipped with cruise control, install the servo.
  22.  
  23. Install the air crossover and connect the breather pipes to the rocker covers and the air crossover.
  24.  
  25. Install the thermostat, gasket and housing bolts to the intake manifold.
  26.  
  27. Refill the radiator with engine coolant.
  28.  
  29. Connect the negative battery cable and install the air cleaner.
  30.  
  31. Start the engine and check for leaks and proper engine operation.
  32.  



Click image to see an enlarged view

Fig. Fig. 7: Exploded view of a diesel intake manifold assembly



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Fig. Fig. 8: Diesel intake manifold tightening sequence



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Fig. Fig. 9: Removing the intake manifold bolts



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Fig. Fig. 10: Make sure all ground connections have been removed from the intake manifold



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Fig. Fig. 11: Removing the intake manifold from the engine

 
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