Jeep Wrangler/YJ 1987-1995 Repair Guide

Intake Manifold

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REMOVAL & INSTALLATION



2.5L Engine

See Figures 1 through 15

It may be necessary to remove the throttle body before the intake manifold can be removed.

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the radiator.
  4.  


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.

  1. Remove the air inlet hose from the throttle body and air cleaner.
  2.  
  3. Loosen the accessory drive belt tension and remove the belt from the power steering pump.
  4.  
  5. Remove the power steering pump and brackets from the water pump and intake manifold and support the pump out of the way.
  6.  
  7. Remove the fuel tank filler cap to relieve the fuel tank pressure, then reinstall the cap.
  8.  
  9. Disconnect the fuel supply and return pipes. Remove the fuel rail, as required.
    1. Remove and numerically tag the injector harness connectors at each injector.
    2.  
    3. Remove the fuel rail retaining bolts and gently rock the rail assembly until all the injectors are out of the intake manifold.
    4.  

  10.  
  11. Label and disconnect all vacuum hoses and sensor connectors.
  12.  
  13. Disconnect the throttle cable from the bellcrank.
  14.  
  15. Disconnect the throttle valve linkage, if equipped with automatic transmission.
  16.  
  17. Remove intake manifold attaching bolts 2 through 5, then slightly loosen bolt No. 1 as well as nuts 6 and 7. Remove the intake manifold and discard the gasket.
  18.  
  19. Clean the mating surfaces of the manifold and cylinder head.
  20.  

To install:

If the manifold is being replaced, ensure that all fittings, etc. are transferred to the replacement manifold.

  1. Install the intake manifold gasket over the locating dowels.
  2.  
  3. Install the manifold in place and finger tighten the mounting bolts.
  4.  
  5. Torque the manifold fasteners as follows:
    1. Tighten fastener No. 1 to 30 ft. lbs. (41 Nm).
    2.  
    3. Tighten fasteners No. 2 through No. 7 to 23 ft. lbs. (31 Nm).
    4.  

  6.  



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Fig. Fig. 1: Intake/exhaust manifold installation and torque sequence-1989-91 2.5L engine



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Fig. Fig. 2: Intake/exhaust manifold installation and torque sequence-1992-95 2.5L engine



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Fig. Fig. 3: Remove the air inlet hose from the throttle body and air cleaner



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Fig. Fig. 4: Remove the retainer securing the accelerator cable to the throttle body



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Fig. Fig. 5: Disconnect the accelerator cable from the throttle body



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Fig. Fig. 6: Remove the accelerator cable hold-down bracket retaining bolts



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Fig. Fig. 7: The accelerator cable hold-down bracket shown disconnected from the manifold



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Fig. Fig. 8: Removing the fuel rail retaining bolts



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Fig. Fig. 9: Removing the vacuum hose at the brake booster



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Fig. Fig. 10: Disconnect and tag all vacuum hoses related to intake manifold removal



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Fig. Fig. 11: Unfasten and tag the electrical connector from the Manifold Air Temperature (MAT) sensor



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Fig. Fig. 12: Unfasten and tag the electrical connector from the Automatic Idle Speed (AIS) motor



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Fig. Fig. 13: Unfasten and tag the electrical connector from the Throttle Position Sensor (TPS)



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Fig. Fig. 14: Removing the intake manifold retaining bolts



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Fig. Fig. 15: Removing the intake manifold from the vehicle

  1. Connect the EGR valve tube to the intake manifold.
  2.  
  3. Connect the throttle valve linkage, if equipped with automatic transmission.
  4.  
  5. Connect the intake manifold electric heater wire connector, as required.
  6.  
  7. On vehicles equipped with power steering, install the power steering pump and its mounting bracket.
  8.  
  9. Connect the vacuum to from the EGR valve.
  10.  
  11. Connect the system coolant temperature sender wire connector (located on the intake manifold). Connect the air temperature sensor wire, if equipped.
  12.  
  13. If equipped, install the vacuum advance CTO valve vacuum hoses.
  14.  
  15. Install the throttle body. Torque the throttle body mounting bolts to 14 ft. lbs. (19 Nm).
  16.  
  17. Connect the PCV valve vacuum hose to the intake manifold.
  18.  
  19. Connect the throttle cable to the bellcrank.
  20.  
  21. Connect the fuel pipe.
  22.  
  23. Connect the coolant hoses to the intake manifold.
  24.  
  25. Install the air cleaner.
  26.  
  27. Connect the negative battery cable.
  28.  
  29. Fill the cooling system.
  30.  

4.0L Engine

See Figure 16

The intake and exhaust manifold are mounted externally on the left side of the engine and are attached to the cylinder head. They are removed as a unit.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Disconnect the accelerator cable, cruise control cable, if equipped and transmission line pressure cable.
  6.  
  7. Disconnect all electrical connectors on the intake manifold.
  8.  
  9. Disconnect and remove the fuel supply and return lines from the fuel rail assembly.
  10.  
  11. Remove the fuel rail and injectors.
  12.  
  13. Loosen the accessory drive belts.
  14.  
  15. Remove the power steering pump.
  16.  
  17. Disconnect the exhaust pipe from the manifold and discard the seal.
  18.  
  19. Remove the intake and exhaust manifold.
  20.  



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Fig. Fig. 16: Intake/exhaust manifold installation and torque sequence-4.0L engine

To install:
  1. Clean the gasket mating surfaces thoroughly. Install a new gasket over the alignment dowels and position the exhaust manifold to the cylinder head. Install bolt No. 3 finger-tight.
  2.  
  3. Install the intake manifold and the remaining bolts and washers.
  4.  
  5. Tighten bolts, in sequence, to the following torque specifications:
    1. Bolts 1-5-24 ft. lbs. (33 Nm)
    2.  
    3. Bolts 6 and 7-17 ft. lbs. (23 Nm)
    4.  
    5. Bolts 8-11-24 ft. lbs. (33 Nm)
    6.  

  6.  
  7. Install the fuel rail and injectors.
  8.  
  9. Install the power steering pump and tension the accessory belt to specification.
  10.  
  11. Using new O-rings, install the fuel supply and return lines.
  12.  
  13. Connect all electrical connectors, vacuum connectors, throttle cable, cruise control cable and transmission lines pressure cable.
  14.  
  15. Install the air cleaner assembly.
  16.  
  17. Using a new seal, connect the exhaust pipe to the manifold and torque the bolts to 23 ft. lbs. (31 Nm).
  18.  
  19. Connect the negative battery cable.
  20.  
  21. Start the engine and check for leaks.
  22.  

4.2L Engine

See Figures 17 and 18

The intake manifold and exhaust manifold are mounted externally on the left side of the engine and are attached to the cylinder head. The intake and exhaust manifolds are removed as a unit. On some engines, an exhaust gas recirculation valve is mounted on the side of the intake manifold.

  1. Remove the air cleaner and carburetor.
  2.  
  3. Disconnect the accelerator cable from the accelerator bellcrank.
  4.  
  5. Disconnect the PCS vacuum hose from the intake manifold.
  6.  
  7. Disconnect the distributor vacuum hose and electrical wires at the TCS solenoid vacuum valve.
  8.  
  9. Remove the TCS solenoid vacuum valve and bracket from the intake manifold. In some cases it might not be necessary to remove the TCS unit.
  10.  
  11. If so equipped, disconnect the EGR valve vacuum hoses.
  12.  
  13. Remove the power steering mounting bracket and pump and set it aside without disconnecting the hoses.
  14.  
  15. Remove the EGR valve, if so equipped.
  16.  
  17. Disconnect the exhaust pipe from the manifold flange. Disconnect the spark CTO hoses and remove the oxygen sensor.
  18.  
  19. Remove the manifold attaching bolts, nuts and clamps.
  20.  
  21. Separate the intake manifold and exhaust manifold from the engine as an assembly. Discard the gasket.
  22.  
  23. If either manifold is to be replaced, they should be separated at the heat riser area.
  24.  



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Fig. Fig. 17: Intake/exhaust manifold installation and torque sequence-4.2L engine



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Fig. Fig. 18: Intake manifold installation-4.2L engine

To install:
  1. Clean the mating surfaces of the manifolds and the cylinder head before replacing the manifolds. Replace them in reverse order of the above procedure with a new gasket. Tighten the bolts and nuts to the specified torque in the proper sequence.
  2.  
  3. Connect the exhaust pipe to the manifold flange. Torque the nuts to 20 ft. lbs. (27 Nm). Connect the spark CTO hoses and install the oxygen sensor.
  4.  
  5. Install the EGR valve, if so equipped.
  6.  
  7. Install the power steering mounting bracket and pump.
  8.  
  9. If so equipped, connect the EGR valve vacuum hoses.
  10.  
  11. Install the TCS solenoid vacuum valve and bracket to the intake manifold.
  12.  
  13. Connect the distributor vacuum hose and electrical wires at the TCS solenoid vacuum valve.
  14.  
  15. Connect the PCS vacuum hose to the intake manifold.
  16.  
  17. Connect the accelerator cable to the accelerator bellcrank.
  18.  
  19. Install the air cleaner and carburetor.
  20.  

 
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