Jeep CJ/Scrambler 1971-1986 Repair Guide

Intake Manifold

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

REMOVAL & INSTALLATION



4-134 Engine

On the F4-134 engine the intake manifold is cast as an integral part of the head.

4-150 Engine

It may be necessary to remove the carburetor or the throttle body from the intake manifold before the manifold is removed.

  1. Disconnect the negative battery cable. 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. Remove the air cleaner. Disconnect the fuel pipe. Remove the carburetor or the throttle body, as required.
  2.  
  3. Disconnect the coolant hoses from the intake manifold.
  4.  
  5. Disconnect the throttle cable from the bellcrank.
  6.  
  7. Disconnect the PCV valve vacuum hose from the intake manifold.
  8.  
  9. If equipped, remove the vacuum advance CTO valve vacuum hoses.
  10.  
  11. Disconnect the system coolant temperature sender wire connector (located on the intake manifold). Disconnect the air temperature sensor wire, if equipped.
  12.  
  13. Disconnect the vacuum hose from the EGR valve.
  14.  
  15. On vehicles equipped with power steering remove the power steering pump and its mounting bracket. Do not detach the power steering pump hoses.
  16.  
  17. Disconnect the intake manifold electric heater wire connector, as required.
  18.  
  19. Disconnect the throttle valve linkage, if equipped with automatic transmission.
  20.  
  21. Disconnect the EGR valve tube from the intake manifold.
  22.  
  23. Remove the intake manifold attaching screws, nuts and clamps. Remove the intake manifold. Discard the gasket.
  24.  
  25. Clean the mating surfaces of the manifold and cylinder head.
  26.  

To install:

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

  1. Install the intake manifold. Install the intake manifold attaching screws, nuts and clamps. Torque manifold fasteners to 23 ft. lbs.
  2.  
  3. Connect the EGR valve tube to the intake manifold.
  4.  
  5. Connect the throttle valve linkage, if equipped with automatic transmission.
  6.  
  7. Connect the intake manifold electric heater wire connector, as required.
  8.  
  9. On vehicles equipped with power steering install the power steering pump and its mounting bracket.
  10.  
  11. Connect the vacuum to from the EGR valve.
  12.  
  13. Connect the system coolant temperature sender wire connector (located on the intake manifold). Connect the air temperature sensor wire, if equipped.
  14.  
  15. If equipped, install the vacuum advance CTO valve vacuum hoses.
  16.  
  17. Install the carburetor or the throttle body. Torque the carburetor or throttle body mounting bolts to 14 ft. lbs.
  18.  
  19. Connect the PCV valve vacuum hose to the intake manifold.
  20.  
  21. Connect the throttle cable to the bellcrank.
  22.  
  23. Connect the fuel pipe.
  24.  
  25. Connect the coolant hoses to the intake manifold.
  26.  
  27. Install the air cleaner.
  28.  
  29. Connect the negative battery cable.
  30.  
  31. Fill the cooling system.
  32.  



Click image to see an enlarged view

Fig. Fig. 1: Combination manifold as used on the 4-150 engine

4-151 Engine
  1. Remove the negative cable.
  2.  
  3. Remove the air cleaner and the PCV valve hose.
  4.  


CAUTION
DO NOT remove the block drain plugs or loosen the radiator draincock the with system hot and under pressure because serious burns from the coolant can occur.

  1. 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. Tag and remove the vacuum hoses (ensure the distributor vacuum advance hose is removed).
  2.  
  3. Disconnect the fuel pipe and electrical wire connections from the carburetor.
  4.  
  5. Disconnect the carburetor throttle linkage. Remove the carburetor and the carburetor spacer.
  6.  
  7. Remove the bellcrank and throttle linkage brackets and move them to one side for clearance.
  8.  
  9. Remove the heater hose at the intake manifold.
  10.  
  11. Remove the alternator. Note the position of spacers for installation.
  12.  
  13. Remove the manifold-to-cylinder head bolts and remove the manifold.
  14.  

To install:
  1. Position the replacement gasket and install the replacement manifold on the cylinder head. Start all bolts.
  2.  
  3. Tighten all bolts with 37 ft. lbs.
  4.  
  5. Connect the heater hose to the intake manifold.
  6.  
  7. Install the bellcrank and throttle linkage brackets.
  8.  
  9. Connect the carburetor throttle linkage to the brackets and bellcrank.
  10.  
  11. Install the carburetor spacer and tighten the bolts with 15 ft. lbs.
  12.  
  13. Install the carburetor and gasket. Tighten the nuts with 15 ft. lbs.
  14.  
  15. Install the fuel pipe and electrical wire connections. Install the vacuum hoses.
  16.  
  17. Install the battery negative cable.
  18.  


CAUTION
Use extreme caution when the engine is operating! Do not stand in a direct line with the fan! Do not put your hands near pulleys, belts or fan! Do not wear loose clothing!

  1. Refill the cooling system. Start the engine and inspect for leaks.
  2.  
  3. Install the air cleaner and the PCV valve hose.
  4.  



Click image to see an enlarged view

Fig. Fig. 2: Intake manifold installation on 4-151

6-225 Engine
  1. 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. Disconnect the crankcase vent hose, distributor vacuum hose, and the fuel line from the carburetor.
  2.  
  3. Disconnect the two distributor leads from the coil.
  4.  
  5. Disconnect the wire from the temperature sending unit.
  6.  
  7. Remove the ten cap bolts that hold the intake manifold to the cylinder head. They must be replaced in their original location.
  8.  
  9. Remove the intake manifold assembly and gasket from the engine.
  10.  
  11. Reverse the above procedure for installation. Tighten the bolts to the correct torque, and in the proper sequence.
  12.  



Click image to see an enlarged view

Fig. Fig. 3: Intake manifold tightening sequence on 6-225 engines



Click image to see an enlarged view

Fig. Fig. 4: Intake manifold tightening sequence on 6-232 and 6-258 engine

6-232 and 6-258 Engine

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.  

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. 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.  

8-304 Engine
  1. Drain the coolant from 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. Remove the air cleaner assembly.
  2.  
  3. Disconnect the spark plug wires. Remove the spark plug wire brackets from the valve covers, and the bypass valve bracket.
  4.  
  5. Disconnect the upper radiator hose and the by-pass hose from the intake manifold. Disconnect the heater hose from the rear of the manifold.
  6.  
  7. Disconnect the ignition coil bracket and lay the coil aside.
  8.  
  9. Disconnect the TCS solenoid vacuum valve from the right side valve cover.
  10.  
  11. Disconnect all lines, hoses, linkages and wires from the carburetor and intake manifold and TCS components as required.
  12.  
  13. Disconnect the air delivery hoses at the air distribution manifolds.
  14.  
  15. Disconnect the air pump diverter valve and lay the valve and the bracket assembly, including the hoses, forward of the engine.
  16.  
  17. Remove the intake manifold after removing the cap bolts that hold it in place. Remove and discard the side gaskets and the end seals.
  18.  

To install:
  1. Clean the mating surfaces of the intake manifold and the cylinder head before replacing the intake manifold. Use new gaskets and tighten the cap bolts to the correct torque. Install in reverse order of the above procedure.
  2.  

There is no specified tighten sequence for this intake manifold. Start at the center bolts and work outward.

  1. Connect the air pump diverter valve.
  2.  
  3. Connect the air delivery hoses at the air distribution manifolds.
  4.  
  5. Connect all lines, hoses, linkages and wires to the carburetor and intake manifold and TCS components as required.
  6.  
  7. Install the TCS solenoid vacuum valve to the right side valve cover.
  8.  
  9. Install the ignition coil bracket.
  10.  
  11. Connect the upper radiator hose and the by-pass hose to the intake manifold. Connect the heater hose to the rear of the manifold.
  12.  
  13. Connect the spark plug wires. Install the spark plug wire brackets on the valve covers, and the bypass valve bracket.
  14.  
  15. Install the air cleaner assembly.
  16.  
  17. Fill the cooling system.
  18.  



Click image to see an enlarged view

Fig. Fig. 5: After removing the mounting bolts, carefully pry up the edge of the manifold to loosen it



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Fig. Fig. 6: Lift the manifold off of the engine



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Fig. Fig. 7: Remove the intake manifold gaskets



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Fig. Fig. 8: Remove the front manifold seals before installing the new gaskets, be sure to replace this gasket

 
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