GM Prizm/Nova 1985-1993 Repair Guide

Combination Manifolds

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REMOVAL & INSTALLATION



1985-88 VIN CODE 4 Engine

See Figure 1

The intake and exhaust manifolds on the 4A-LC engine are a 1-piece or combination design. They can not be separated from each other or removed individually.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Label and disconnect all vacuum hoses at the carburetor.
  6.  
  7. Disconnect the accelerator cable and, for automatic transmissions, the throttle cable.
  8.  
  9. Label and disconnect the electrical connections at the carburetor.
  10.  
  11. Disconnect the fuel line at the fuel pump.
  12.  
  13. Carefully loosen and remove the carburetor mounting bolts and remove the carburetor.
  14.  


CAUTION
The carburetor bowls contain gasoline which may spill or leak during removal. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

Keep the carburetor level during removal and handling. As soon as it is off the car, wrap or cover it with a clean towel to keep dirt out.

  1. Remove the Early Fuel Evaporation (EFE) gasket.
  2.  
  3. Remove the vacuum line and dashpot bracket.
  4.  
  5. Carefully remove the heat shields on the manifold; don't break the bolts.
  6.  
  7. Safely elevate and support the vehicle on jackstands.
  8.  
  9. Disconnect the exhaust pipe at the manifold and exhaust bracket at the engine.
  10.  
  11. Remove the hose at the converter pipe.
  12.  
  13. Lower the car to the ground and remove or disconnect the vacuum hose to the brake booster.
  14.  
  15. Remove the bracket for the accelerator and throttle cables.
  16.  
  17. Evenly loosen and then remove the bolts and nuts holding the manifold to the engine. Remove the manifold and its gaskets.
  18.  
  19. Using a precision straight edge and a feeler gauge, check the mating surfaces of the manifold for warpage. If the warpage is greater than the maximum allowable specification, replace the manifold.
  20.  

Maximum permitted warpage:


Intake 0.2mm;
 
Exhaust 0.3mm
 



Click image to see an enlarged view

Fig. Fig. 1: Measuring the manifold for warpage - 1985-88 VIN Code 4 engine

To install:
  1. When reinstalling, always use new gaskets and make sure they are properly positioned. Place the manifold in position and loosely install the nuts and bolts until all are just snug. Double check the placement of the manifold and in 2 passes tighten the retaining nuts and bolts to 18 ft. lbs.
  2.  
  3. Reinstall the bracket for the accelerator and throttle cables and connect the vacuum hose to the brake vacuum booster.
  4.  
  5. Elevate and safely support the car on jackstands.
  6.  
  7. Reconnect the hose at the converter pipe. Install the exhaust bracket at the engine and, using new gaskets, connect the exhaust pipe to the manifold.
  8.  
  9. Lower the vehicle to the ground. Install the heat shield onto the manifold.
  10.  
  11. Reinstall the vacuum line and the dashpot bracket.
  12.  
  13. Install the EFE gasket.
  14.  
  15. Reinstall the carburetor. Slowly and evenly tighten the mounting nuts and bolts to 8-10 ft. lbs. Connect the electrical connectors to the carburetor.
  16.  
  17. Connect and secure the fuel line to the fuel pump.
  18.  
  19. Attach the accelerator cable and throttle valve cable (automatic trans.).
  20.  
  21. 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. double check each line for crimps or twists.
  22.  
  23. Install the air cleaner assembly and connect the negative battery cable.
  24.  

 
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