GM Cadillac 1967-1989 Repair Guide

Exhaust Manifold

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REMOVAL & INSTALLATION



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

Except 6-252, 8-250, 8-307 and 8-350 Engines

Before attempting this procedure it may be easier to remove the crossover pipe. On California emission equipped cars the Oxygen sensor and the A.I.R. hoses must be removed before removal of the exhaust manifold.

  1. In order to remove the left exhaust manifold, remove the air cleaner assembly and the heat duct. Remove the nuts from the no. 2 and no. 8 cylinder (no. 2 and no. 6 on the Eldorado) manifold studs and heat shroud from around the manifold.
  2.  
  3. Unfasten the nuts which secure the downpipe to either manifold. Remove the two studs retaining the EFE valve to the right side manifold and remove the EFE valve. EFI equipped cars have a spacer in place of the EFE valve.
  4.  
  5. Remove the bolts which secure the manifold to the cylinder heads. If working on the left manifold on the Eldorado, also remove the clip securing the dipstick tube.
  6.  

It may not be possible to remove the fifth bolt from the front of the cylinder heads on some Cadillac engines. Back the bolt all the way out and remove it with the manifolds.

  1. Lift the manifold out of the engine compartment.
  2.  
  3. Installation is the reverse of removal. Lubricate the cylinder head installation surface with moly grease. Install the fifth bolt from the front prior to installing the manifold. Tighten the bolts to specifications. On the right manifold, position the EFE valve (spacer on EFI equipped cars) on the manifold with the actuator toward the engine block. Tighten the two stud bolts.
  4.  



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Fig. Fig. 1: Exhaust manifold installation - 8-368 engine shown others similar

6-252 Engine
  1. Remove the three upper exhaust manifold bolts. Be careful not to break the spark plug noise suppression bracket.
  2.  
  3. Raise the car and safely support it on jackstands.
  4.  
  5. Disconnect the exhaust crossover pipe.
  6.  
  7. Disconnect the EFE pipe on the left side and remove the EFE valve.
  8.  
  9. Remove the two lower exhaust manifold-to-cylinder head bolts.
  10.  
  11. Carefully lower the exhaust manifold and remove from beneath the car.
  12.  
  13. Installation is the reverse of removal
  14.  

8-350 EFI and Diesel Engines

LEFT SIDE



  1. Remove the air cleaner.
  2.  
  3. Remove the lower alternator bracket.
  4.  
  5. Raise the car and support on jackstands. Disconnect the crossover pipe.
  6.  
  7. Lower the car and remove the manifold from above.
  8.  
  9. Installation is the reverse of the removal.
  10.  

RIGHT SIDE
  1. Raise the car and support on jackstands.
  2.  
  3. Disconnect the crossover and exhaust pipes.
  4.  
  5. Remove the right front wheel.
  6.  
  7. Remove the exhaust manifold from under the car.
  8.  
  9. Installation is the reverse of the removal.
  10.  

8-250 and 273 Engines

LEFT SIDE



  1. Remove the air cleaner and tube assembly from the preheat stove.
  2.  
  3. Remove the one screw securing the oil dipstick tube to the preheat stove.
  4.  
  5. Remove the preheat stove from the manifold.
  6.  
  7. Disconnect the Y-pipe from the exhaust manifold.
  8.  
  9. Remove the oxygen sensor using a 1 inch box end wrench.
  10.  
  11. Remove the exhaust manifold retaining bolts and remove the exhaust manifold from the car.
  12.  

To install:
  1. Installation is the reverse of removal. Apply a thin layer of graphite dry film lubricant to the areas of the exhaust manifold which will contact the cylinder head and heat stove. Failure to do this may result in exhaust manifold cracking after prolonged driving.
  2.  
  3. Tighten the manifold bolts to 18 ft. lbs. (24 Nm).
  4.  

RIGHT SIDE



  1. Remove the nut securing the transmission cooler line bracket to the exhaust manifold.
  2.  
  3. Remove the two nuts retaining the air valve bracket to the manifold.
  4.  
  5. Remove the upper exhaust manifold to head bolts.
  6.  
  7. Jack up the car and safely support with jackstands.
  8.  
  9. Remove the lower exhaust manifold to head bolts.
  10.  
  11. Disconnect the exhaust Y-pipe from the manifold and remove the exhaust manifold from the engine.
  12.  

To install:
  1. Installation is the reverse of removal. Apply a thin layer of graphite dry film lubricant to the areas of the exhaust manifold which will contact the cylinder head. Failure to do this may result in exhaust manifold cracking after prolonged driving.
  2.  
  3. Tighten the manifold bolts to 18 ft. lbs. (24 Nm).
  4.  

8-307 Engine

RIGHT SIDE



  1. Disconnect the negative battery cable.
  2.  
  3. Raise and support the vehicle on jackstands.
  4.  
  5. Remove the exhaust pipe bolts, then lower the vehicle.
  6.  
  7. Remove the air cleaner.
  8.  
  9. Disconnect the spark plug wires from the spark plugs, the vacuum hoses from the carbon canister and the AIR hose(s).
  10.  
  11. Loosen the alternator belt, then remove the lower alternator bracket and the AIR valve.
  12.  
  13. Disconnect the converter's AIR pipe from the back of the manifold.
  14.  
  15. Remove the exhaust manifold bolts and the manifold.
  16.  
  17. Using a putty knife, clean the gasket mounting surfaces.
  18.  
  19. To install, use new gaskets and reverse the removal procedures. Adjust the drive belts. Start the engine and check for leaks.
  20.  

LEFT SIDE
  1. Disconnect the negative battery cable.
  2.  
  3. Raise and support the vehicle on jackstands.
  4.  
  5. Remove the exhaust pipe from the manifold, then lower the vehicle.
  6.  
  7. Disconnect the AIR hose.
  8.  
  9. If equipped with air conditioning, loosen the bracket at the front of the head, then remove the rear bracket and the compressor.
  10.  
  11. If equipped with power steering, remove the power steering pump and the lower adjusting bracket.
  12.  
  13. Remove the exhaust manifold bolts, the wire loom holder at the valve cover and the manifold.
  14.  
  15. Using putty knife, clean the gasket mounting surfaces.
  16.  
  17. To install, use new gaskets and reverse the removal procedures. Adjust the drive belts. Start the engine and check for leaks.
  18.  



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Fig. Fig. 2: Left hand exhaust manifold - 1982-85 8-250 engine



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Fig. Fig. 3: Right hand exhaust manifold - 1982-85 8-250 engine



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Fig. Fig. 4: 8-350 diesel engine exhaust manifold installation



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Fig. Fig. 5: Exhaust manifolds - 1986-87 8-250 engine



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Fig. Fig. 6: Exhaust manifold - 8-273 engine



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Fig. Fig. 7: Left side exhaust manifold - 8-307 engine



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Fig. Fig. 8: Right side exhaust manifold - 8-307 engine



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Fig. Fig. 9: Removing the heat shield - exhaust manifold removal



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Fig. Fig. 10: Remove all necessary components - common exhaust manifold removal



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Fig. Fig. 11: Removing the exhaust manifold - always replace gasket

 
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