AMC Coupes/Sedans/Wagons 1975-1988 Repair Information

Exhaust Manifold

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REMOVAL & INSTALLATION 4-121 Engine



See Figure 1

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Fig. Fig. 1: Typical exhaust manifold used on 4-121 engines

  1. Remove the TAC cold air induction manifold assembly and components.
  2.  
  3. Disconnect the EGR tube from the manifold.
  4.  
  5. Remove the exhaust pipe from the manifold.
  6.  
  7. Remove the manifold retaining nuts and washers.
  8.  
  9. Remove the manifold and gasket from the engine.
  10.  
  11. Clean the mating surfaces of the manifold and the head.
  12.  

To install:
  1. Install a new gasket on the head and install the manifold. Install, but do not tighten, the exhaust manifold nuts until the EGR tube is attached to the exhaust manifold, then torque the manifold nuts to 18 ft. lbs.
  2.  
  3. Install the exhaust pipe to the manifold. Torque the nuts to 18 ft. lbs.
  4.  
  5. Connect the EGR tube to the manifold.
  6.  
  7. Install the TAC cold air induction manifold assembly and components.
  8.  

4-150 Engine See Figures 2 and 3

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Fig. Fig. 2: Exhaust manifold bolt tightening sequence4-150 engine



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Fig. Fig. 3: Exhaust manifold modification on the 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.  

To install:
  1. If a new manifold is being installed, transfer the oxygen sensor. Torque the sensor to 35 ft. lbs.
  2.  
  3. Thoroughly clean the gasket mating surfaces of the manifold and head.
  4.  
  5. Install the manifold, using a new gasket. Torque the nuts to 23 ft. lbs.
  6.  
  7. Connect the oxygen sensor wire.
  8.  
  9. Connect the exhaust pipe at the manifold.
  10.  
  11. Connect the EGR tube.
  12.  
  13. Install the intake manifold.
  14.  

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

  1. Remove the manifold.
  2.  
  3. Replace any bent or broken studs.
  4.  
  5. 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.
  6.  
  7. Modify the original or replacement manifold by grinding the mounting flanges as shown in the accompanying illustration.
  8.  
  9. Install the manifold.
  10.  

4-151 Engine See Figures 4, 5, 6 and 7

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Fig. Fig. 4: Exhaust manifold bolt tightening sequence4-151 engine



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Fig. Fig. 5: Unbolt the exhaust pipe from the manifold



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Fig. Fig. 6: Unfasten the exhaust manifold retaining bolts ...



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Fig. Fig. 7: ... then remove the manifold from the engine

  1. Remove the air cleaner and the hot air tube.
  2.  
  3. Remove the Pulsair system from the exhaust manifold.
  4.  
  5. Disconnect the exhaust pipe from the manifold at the flange. Spray the bolts first with penetrating sealer, if necessary.
  6.  
  7. Remove the engine oil dipstick bracket bolt.
  8.  
  9. Remove the exhaust manifold bolts and remove the manifold from the head.
  10.  

To install:
  1. Place a new gasket against the cylinder head, then install the exhaust manifold over it. Start all the bolts into the head finger-tight.
  2.  
  3. Torque the exhaust manifold bolts to 37 ft. lbs. in two stages, using the torque sequence illustrated.
  4.  
  5. The remainder of installation is the reverse removal.
  6.  

6-Cylinder Engines

The exhaust manifold is removed along with the intake manifold. Refer to the intake manifold procedure in this section.

V8 Engines

EXCEPT 1975-76 GREMLIN AND HORNET WITH AIR PUMP

The mating surfaces of both the exhaust manifold and the cylinder head are machined smooth, thus eliminating any need for a gasket between them.

  1. Disconnect the wires from the spark plugs after marking them for firing order.
  2.  
  3. On models equipped with air injection, disconnect the air delivery hoses from the injection manifold. Remove the injection manifold and nozzles from the exhaust manifold.
  4.  
  5. Disconnect the exhaust pipe from the exhaust manifold flange.
  6.  
  7. Remove the bolts and washers used to retain the manifold.
  8.  
  9. Remove the shields from the spark plugs. On 1977 and later Hornets and Concords only, before removing the right side manifold, remove the transmission filler tube bolt and tube.
  10.  
  11. Remove the exhaust manifold from the cylinder head.
  12.  
  13. Clean the machined surfaces of the manifold and head.
  14.  

To install:
  1. Install the exhaust manifold on the cylinder head.
  2.  
  3. Install the shields on the spark plugs. On 1977 and later Hornets and Concords only, install the transmission filler tube bolt and tube. Use a new O-ring when installing the tube.
  4.  
  5. Connect the exhaust pipe from the exhaust manifold flange.
  6.  
  7. On models equipped with air injection, install the injection manifold and nozzles on the exhaust manifold. Connect the air delivery hoses at the injection manifold.
  8.  
  9. Connect the wires at the spark plugs.
  10.  

1975-76 GREMLIN AND HORNET WITH AIR PUMP

The exhaust manifold on the left side may be removed in the same manners detailed for other V8 engines; however, the right side manifold on Gremlins and Hornets equipped with air pumps must be removed in the following order:

  1. Raise the car and securely support it with jackstands.
  2.  
  3. Disconnect the exhaust pipe from the manifold flange.
  4.  
  5. Support the engine at the vibration damper, by placing a jack with a block of wood on its lifting pad underneath it.
  6.  
  7. Remove the bolts which secure the engine mounting bracket on the right side.
  8.  
  9. Remove the air cleaner assembly, including the tube which runs to the manifold heat stove.
  10.  
  11. Disconnect the battery cables. Remove the spark plug leads after marking them for installation.
  12.  
  13. Disconnect the air supply hose from the air injection manifold.
  14.  
  15. Remove the air injection tubes from the exhaust manifold.
  16.  
  17. On cars with automatic transmissions, remove the dipstick and the screw which secures the transmission dipstick tube.
  18.  
  19. Working from the rear, unscrew the exhaust manifold mounting bolts.
  20.  
  21. Raise the engine. Remove the exhaust manifold and the air injection manifold as an assembly.
  22.  
  23. Clean the joining surfaces of the manifold and cylinder head. Be careful not to nick or scratch either surface.
  24.  

To install:
  1. Install the exhaust manifold and the air injection manifold as an assembly.
  2.  
  3. On cars with automatic transmissions, install the dipstick and the screw which secures the transmission dipstick tube.
  4.  
  5. Install the air injection tubes.
  6.  
  7. Connect the air supply hose at the air injection manifold.
  8.  
  9. Connect the battery cables. Install the spark plug leads.
  10.  
  11. Install the air cleaner assembly, including the tube which runs to the manifold heat stove.
  12.  
  13. Install the bolts which secure the engine mounting bracket on the right side.
  14.  
  15. Remove the jack.
  16.  
  17. Connect the exhaust pipe at the manifold flange.
  18.  
  19. Raise the car and securely support it with jackstands.
  20.  

 
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