GM Prizm/Nova 1985-1993 Repair Guide

Exhaust Manifold

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REMOVAL & INSTALLATION



1988 VIN Code 5 Engine

See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the cooling system.
  4.  


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. Remove the upper radiator hose at the engine.
  4.  
  5. Disconnect the accelerator cable and, on automatic transmissions, the throttle valve cable.
  6.  
  7. Label and disconnect vacuum hoses at the manifolds.
  8.  
  9. Disconnect and remove the fuel delivery pipe (fuel rail) and remove the injectors. During removal, be careful not to drop the injectors.
  10.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Disconnect the vacuum hose to the brake booster and remove the heat shield(s) from the manifold(s).
  2.  
  3. Safely raise the car and support it on jackstands.
  4.  
  5. Disconnect the wire for the water temperature sensor and remove the water outlet housing (thermostat housing) and the bypass pipe.
  6.  
  7. Remove the exhaust bracket and disconnect the exhaust pipe at the manifold. Remove the support bracket for the intake manifold.
  8.  
  9. Lower the vehicle to the ground.
  10.  
  11. Remove the intake manifold with the air control valve and gaskets and/or remove the exhaust manifold with its gaskets.
  12.  
  13. Using a precision straight edge and a feeler gauge, check the mating surfaces of the manifolds for warpage. If the warpage is greater than the maximum allowable specification, replace the manifold.
  14.  

Maximum allowable warpage:


Intake Manifold: 0.05mm;
 
Exhaust Manifold: 0.3mm;
 
Air Control Valve: 0.05mm.
 

To install:
  1. When reinstalling, always use new gaskets and make sure they are properly positioned. Place the manifold(s) in position and loosely install the nuts and bolts until all are just snug. Double check the placement of the manifold(s) and in 2 passes tighten the retaining nuts and bolts. The exhaust manifold retaining bolts should be tightened to 18 ft. lbs. and the intake manifold bolts should be tightened to 20 ft. lbs. The bolts for the intake support bracket should also be tightened to 20 ft. lbs
  2.  
  3. With the manifold(s) in place, elevate and support the vehicle; install the support bracket for the intake manifold and connect the exhaust pipe to the exhaust manifold. Attach the exhaust bracket.
  4.  
  5. Install the bypass pipe, the water outlet housing and connect the wiring to the water temperature sensor.
  6.  
  7. Lower the car to the ground and install the heat shield(s) on the manifolds.
  8.  
  9. Connect the vacuum hose for the brake vacuum booster.
  10.  
  11. Install the fuel delivery pipe and the injectors. Tighten the mounting bolts to 13 ft. lbs.
  12.  
  13. Observing the labels made earlier, install the vacuum lines. Be careful of the routing and make sure that each line fits snugly on its port.
  14.  
  15. Double check each line for crimps or twists.
  16.  
  17. Connect the accelerator cable and throttle valve cable (automatic trans.)
  18.  
  19. Reconnect the upper radiator hose.
  20.  
  21. Install the air cleaner assembly.
  22.  
  23. Refill the coolant.
  24.  
  25. Connect the negative battery cable.
  26.  

1989-90 VIN Code 6 Engine

See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the 5 bolts and remove the upper heat shield (insulator) from the manifold.
  4.  
  5. Raise and safely support the vehicle on jackstands.
  6.  
  7. Disconnect the exhaust pipe from the exhaust manifold and remove the manifold support and its 2 bolts.
  8.  
  9. Lower the vehicle to the ground. Disconnect the oxygen sensor wire.
  10.  
  11. Remove the 2 nuts and 3 bolts holding the manifold to the engine. Remove the manifold and its gaskets. When the manifold is clear of the car, remove the lower heat shield.
  12.  
  13. Measure the exhaust manifold mating surface with a precision straight edge and a feeler gauge. If the warpage exceeds 0.28mm, the manifold must be replaced.
  14.  

To install:
  1. Before reinstalling, attach the lower heat shield to the manifold with the 3 bolts. Tighten the bolts to 18 ft. lbs.
  2.  
  3. Install the manifold with new gaskets and tighten its bolts and nuts to 18 ft. lbs.
  4.  
  5. Raise the car and safely support in on jackstands. Install the manifold support and tighten the bolts to 18 ft. lbs.
  6.  
  7. Connect the exhaust pipe to the manifold with new gaskets and tighten the bolts to 18 ft. lbs.
  8.  
  9. Lower the car to the ground. Install the upper heat shield on the manifold and tighten its 5 bolts to 18 ft. lbs.
  10.  
  11. Connect the wiring to the oxygen sensors.
  12.  
  13. Connect the negative battery cable.
  14.  



Click image to see an enlarged view

Fig. Fig. 1: Location of exhaust manifold attaching hardware - 1989-90 VIN code 6, 1991-92 VIN code 5 and all 1993 engines

1990 VIN Code 5 Engine 1991-92 All Engines

See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove the air cleaner assembly.
  6.  
  7. Remove the upper radiator hose at the engine.
  8.  
  9. Disconnect the accelerator cable and, on automatic transaxles, the throttle valve cable.
  10.  
  11. Label and disconnect vacuum hoses at the manifolds.
  12.  
  13. Disconnect and remove the fuel delivery pipe (fuel rail) and remove the injectors. During removal, be careful not to drop the injectors.
  14.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Disconnect the vacuum hose to the brake booster and remove the heat shield(s) from the manifold(s).
  2.  
  3. Safely raise the vehicle and support it.
  4.  
  5. Disconnect the wire for the water temperature sensor and remove the water outlet housing (thermostat housing) and the bypass pipe.
  6.  
  7. Remove the exhaust bracket and disconnect the exhaust pipe at the manifold. Remove the support bracket for the intake manifold.
  8.  
  9. Lower the vehicle to the ground.
  10.  
  11. Remove the intake manifold with the air control valve and gaskets and/or remove the exhaust manifold with its gaskets.
  12.  

To install:
  1. Using a precision straight edge and a feeler gauge, check the mating surfaces of the manifolds for warpage. If the warpage is greater than the maximum allowable specification, replace the manifold. Maximum allowable warpage: Intake Manifold: 0.05mm; Exhaust Manifold: 0.3mm; Air Control Valve: 0.05mm.
  2.  
  3. When reinstalling, always use new gaskets and make sure they are properly positioned. Place the manifold(s) in position and loosely install the nuts and bolts until all are just snug. Double check the placement of the manifold(s) and in 2 passes tighten the retaining nuts and bolts. The exhaust manifold retaining bolts should be tightened to 18 ft. lbs. (25 Nm) and the intake manifold bolts should be tightened to 20 ft. lbs (27 Nm). The bolts for the intake support bracket should also be tightened to 20 ft. lbs (27 Nm).
  4.  
  5. With the manifold(s) in place, elevate and support the vehicle; install the support bracket for the intake manifold and connect the exhaust pipe to the exhaust manifold. Attach the exhaust bracket.
  6.  
  7. Install the bypass pipe, the water outlet housing and connect the wiring to the water temperature sensor.
  8.  
  9. Lower the vehicle to the ground and install the heat shield(s) on the manifolds.
  10.  
  11. Connect the vacuum hose for the brake vacuum booster.
  12.  
  13. Install the fuel delivery pipe and the injectors. Tighten the mounting bolts to 13 ft. lbs. (18 Nm).
  14.  
  15. Observing the labels made earlier, install the vacuum lines. Be careful of the routing and make sure that each line fits snugly on its port.
  16.  
  17. Double check each line for crimps or twists.
  18.  
  19. Connect the accelerator cable and throttle valve cable (automatic trans.)
  20.  
  21. Reconnect the upper radiator hose.
  22.  
  23. Install the air cleaner assembly.
  24.  
  25. Refill the coolant.
  26.  
  27. Connect the negative battery cable.
  28.  

1993 All Engines

See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the oxygen sensor electrical connector.
  4.  
  5. Remove the 2 exhaust pipe to exhaust manifold bolts and 2 front pipe to exhaust manifold nuts (front pipe to warm up 3 way catalytic converter WU TWC on Calif. spec. vehicles).
  6.  
  7. Remove the 5 bolts and the upper heat insulator.
  8.  
  9. Remove the 3 bolts and the exhaust manifold brace (2 bolts on Calif. spec. vehicles).
  10.  
  11. Remove the 5 nuts, exhaust manifold (WU TWC on Calif. spec. vehicles) and gasket from the cylinder head.
  12.  
  13. Remove the 3 bolts and the lower heat insulator from the exhaust manifold.
  14.  
  15. Remove the 4 nuts and 2 WU TWC heat insulators (Calif. spec. vehicles, if required).
  16.  
  17. Remove the 2 bolts, 2 nuts and WU TWC from exhaust manifold (Calif. spec. vehicles, if required).
  18.  

To install:
  1. Clean the exhaust manifold and cylinder head mating surfaces.
  2.  
  3. Install the 2 bolts, 2 nuts and WU TWC to the exhaust manifold (Calif. spec. vehicles, if removed, and tighten to 22 ft. lbs. (29 Nm)).
  4.  
  5. Install the 4 nuts and 2 WU TWC heat insulators (Calif. spec. vehicles, if removed) and tighten to 80 inch lbs. (9 Nm).
  6.  
  7. Install the 3 bolts and the lower heat insulator to the exhaust manifold and tighten to 80 inch lbs. (9 Nm).
  8.  
  9. Install a new gasket and exhaust manifold (WU TWC on Calif. spec. vehicles) to the cylinder head and tighten the 5 nuts to 25 ft. lbs. (34 Nm).
  10.  
  11. Install the 3 bolts and the exhaust manifold brace (2 bolts on Calif. spec. vehicles) and tighten to 29 ft. lbs (39 Nm).
  12.  
  13. Install the 5 bolts and the upper heat insulator and tighten to 80 inch lbs. (9 Nm).
  14.  
  15. Install the 2 exhaust pipe to exhaust manifold bolts and 2 front pipe to exhaust manifold nuts (front pipe to warm up 3 way catalytic converter WU TWC on Calif. spec. vehicles) and tighten to 46 ft. lbs. (62 Nm).
  16.  
  17. Connect the oxygen sensor electrical connector.
  18.  
  19. Connect the negative battery cable.
  20.  

 
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