Jeep CJ/Scrambler 1971-1986 Repair Guide

Exhaust Manifolds

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See Figures 1, 2, 3 and 4

REMOVAL & INSTALLATION



4-134 Engine
  1. Remove the air delivery hose from the air injection tube assembly if the engine is so equipped. If not, proceed to step two.
  2.  
  3. Remove the five nuts from the manifold studs.
  4.  
  5. Pull the manifold from the mounting studs. Be careful not to damage the air injection tubes if the engine is equipped with an air pump.
  6.  
  7. Remove the gaskets from the cylinder block.
  8.  
  9. If the exhaust manifold is to be replaced it will be necessary to remove the air injection tubes from the exhaust manifold. The application of heat may be necessary to aid removal.
  10.  
  11. Use new gaskets when replacing the exhaust manifold. Make sure that the cylinder head are clean. Tighten the attaching nuts to the correct torque specification.
  12.  
  13. If the exhaust manifold was be replaced, install the air injection tubes. The application of heat may be necessary to aid installation.
  14.  
  15. Install the air delivery hose on the air injection tube assembly if the engine is so equipped.
  16.  

4-150 Engine
  1. Remove the intake manifold.
  2.  
  3. Disconnect the EGR tube.
  4.  
  5. Disconnect the exhaust pipe at the manifold.
  6.  
  7. Disconnect the oxygen sensor wire.
  8.  
  9. Support the manifold and remove the nuts from the studs.
  10.  
  11. If a new manifold is being installed, transfer the oxygen sensor. Torque the sensor to 35 ft. lbs.
  12.  
  13. Thoroughly clean the gasket mating surfaces of the manifold and head.
  14.  
  15. Install the manifold, using a new gasket. Torque the nuts to 23 ft. lbs.
  16.  
  17. Connect the oxygen sensor wire.
  18.  
  19. Connect the exhaust pipe at the manifold.
  20.  
  21. Connect the EGR tube.
  22.  
  23. Install the intake manifold.
  24.  

On some 1984-85 4-150 engines, the manifold end studs can be bent or broken if the manifold is misaligned. To remedy this:



Remove the manifold.
 
Replace any bent or broken studs.
 
Using a straightedge, check the flatness of the manifold mating surface. If a 0.015 in. (0.38mm) flat feeler gauge can be inserted between the straightedge and the manifold, at any point, replace the manifold.
 
Modify the original or replacement manifold by grinding the mounting flanges as shown in the accompanying illustration.
 
Install the manifold
 



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Fig. Fig. 1: Exhaust manifold torque sequence on the 4-150 engine



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Fig. Fig. 2: Exhaust manifold modification on the 4-150 engine

4-151 Engine
  1. Remove the air cleaner and heated air tube.
  2.  
  3. Remove the engine oil dipstick tube attaching bolt.
  4.  
  5. Remove the oxygen sensor, if equipped.
  6.  
  7. Raise the vehicle and disconnect the exhaust pipe from the manifold. Lower the vehicle.
  8.  
  9. Remove the exhaust manifold bolts and remove the manifold and gasket.
  10.  
  11. Install the replacement gasket and the exhaust manifold on the cylinder head. Tighten all bolts to 39 ft. lbs.
  12.  
  13. Install the dipstick tube attaching bolts.
  14.  



Click image to see an enlarged view

Fig. Fig. 3: Exhaust manifold bolt torque sequence on the 4-151 engine

6-225 Engine
  1. Remove the five manifold attaching screws and one nut.
  2.  
  3. Remove the exhaust manifold from the side of the cylinder head.
  4.  
  5. Remove the exhaust manifold gasket from the cylinder head.
  6.  
  7. Use a new gasket when replacing the exhaust manifolds. Make sure that the mating surfaces of the manifold and the cylinder head are clean. Tighten the manifold nuts and bolts to the correct torque.
  8.  

6-232 and 6-258 Engine

The intake and exhaust manifolds of the 232 and 258 cu. in. six cylinder engines must be removed together. See the procedure for removing and installing the intake manifold.

8-304 Engine
  1. Disconnect the spark plug wires.
  2.  
  3. Disconnect the air delivery hose at the distribution manifold.
  4.  
  5. Remove the air distribution manifold and the injection tubes.
  6.  
  7. Disconnect the exhaust pipe at the manifold.
  8.  
  9. Remove the exhaust manifold attaching bolts and washers along with the spark plug shields.
  10.  
  11. Separate the exhaust manifold from the cylinder head.
  12.  
  13. Install in reverse order of the above procedure. Clean the mating surfaces and tighten the attaching bolts to the correct torque.
  14.  



Click image to see an enlarged view

Fig. Fig. 4: Be sure to remove the old exhaust manifold gasket from the cylinder head

 
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