GM Prizm/Nova 1985-1993 Repair Guide

Cylinder Head Cover

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REMOVAL & INSTALLATION



1985-88 VIN Code 4 Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Disconnect the PCV hose.
  6.  
  7. Disconnect the accelerator cable.
  8.  
  9. Disconnect the wire harness.
  10.  
  11. Remove the upper timing belt cover bolts and the cover. Remove the 2 valve cover bolts.
  12.  
  13. Remove the valve cover and its gasket.
  14.  

If the cover is stuck in place, tap a corner with a plastic or rubber mallet. Don't pry the cover up; it will deform and leak.

To install:
  1. Clean the mating surfaces on the head and the cover; install a new gasket.
  2.  
  3. Place the cover and gasket in position on the head. Make sure the cover is straight and that the rubber bushings are on the studs.
  4.  
  5. Install the cover nuts and the upper belt cover with its bolts. Tighten the cover nuts to 15 ft. lbs.
  6.  
  7. Connect the wiring harness, the accelerator cable and the PCV hose.
  8.  
  9. Install the air cleaner assembly and connect the negative battery cable.
  10.  
  11. Start the engine and check for leaks after the engine has warmed up. Minor leaks may be cured by slightly snugging the cover bolts and the timing belt cover bolts. Any leak that is still present after about a 1 / 4 turn CANNOT be cured by further tightening. Remove the cover again and either reposition or replace the gasket.
  12.  

1988 VIN Code 5 Engine 1990 VIN Code 5 Engine 1991-92 VIN Code 6 Engine

See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect or remove the PCV valve, the accelerator cable and the wiring harness.
  4.  
  5. Disconnect the spark plug wires at the plugs and disconnect the wiring to the noise filter.
  6.  
  7. Disconnect the oil pressure sender wire and, if equipped with air conditioning, the wire to the compressor.
  8.  
  9. Remove the center cover (between the cam covers) and its gasket.
  10.  
  11. Remove the cap nuts, the rubber seals and remove the valve covers.
  12.  

If the cover is stuck in place, tap a corner with a plastic or rubber mallet. Don't pry the cover up; it will deform and leak.

To install:
  1. Clean the mating surfaces of the head and the covers.
  2.  
  3. Apply RTV sealant to the cylinder head before reassembly. This step is REQUIRED to prevent oil leakage.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Apply sealant to these points before reinstalling the valve cover - 1988 VIN Code 5 engine

  1. Install the covers with new gaskets. Install the seals and the cap nut, making sure everything is properly seated. tighten the cap nuts to 15 ft. lbs. (20 Nm).
  2.  
  3. Install the center cover with its gasket.
  4.  
  5. Connect the wiring to the oil pressure sender and the compressor, if equipped.
  6.  
  7. Connect the wiring to the noise filter and install the spark plug wires.
  8.  
  9. Connect, in this order, the wiring harness, the accelerator cable, the PCV valve and the negative battery cable.
  10.  
  11. Start the engine and check for leaks after the engine has warmed up. Minor leaks may be cured by slightly snugging the cover bolts. Any leak that is still present after about a 1 / 4 turn CANNOT be cured by further tightening. Remove the cover again and either reposition or replace the gasket.
  12.  

1989-90 VIN Code 6 Engine 1991-92 VIN Code 5 Engine

See Figure 2

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the PCV and the vacuum hose.
  4.  
  5. Loosen the engine wiring harness running over the upper timing belt cover for easier access to the valve cover.
  6.  
  7. Remove the spark plug wires from the spark plugs.
  8.  
  9. Remove the 3 cap nuts, the seals below them and remove the valve cover.
  10.  

To install:
  1. Clean the mating surfaces of the head and the cover. Install a new gasket before installing the valve cover.
  2.  
  3. Apply RTV sealant to the cylinder head as illustrated before reassembly. This step is REQUIRED to prevent oil leakage.
  4.  



Click image to see an enlarged view

Fig. Fig. 2: Apply sealant to these points before reinstalling valve cover - 1989-90 VIN Code 6 and 1991-92 VIN Code 5 engines

  1. Install the covers with new gaskets. Install the seals and the cap nut, making sure everything is properly seated. Tighten the cap nuts to 15 ft. lbs. (20 Nm).
  2.  
  3. Reconnect the spark plug wires and reposition the wiring harness over the timing belt cover.
  4.  
  5. Connect the vacuum hose, the PCV and the negative battery cable.
  6.  
  7. Start the engine and check for leaks after the engine has warmed up. Minor leaks may be cured by slightly snugging the cover bolts. Any leak that is still present after about a 1 / 4 turn CANNOT be cured by further tightening. Remove the cover again and either reposition or replace the gasket.
  8.  

1993 All Engines
  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the PCV and the 2 vacuum hoses.
  4.  
  5. Loosen the engine wiring harness running over the upper timing belt cover for easier access to the valve cover.
  6.  
  7. Remove the spark plug wires from the spark plugs.
  8.  
  9. Remove the 4 cap nuts, the seals below them and remove the cylinder head cover.
  10.  

To install:
  1. Clean the mating surfaces of the head and the cover. Install a new gasket before installing the valve cover.
  2.  
  3. Apply RTV sealant to the cylinder head before reassembly. This step is REQUIRED to prevent oil leakage.
  4.  
  5. Install the covers with new gaskets. Install the seals and the cap nut, making sure everything is properly seated. Tighten the cap nuts to 53 inch lbs. (6 Nm).
  6.  
  7. Reconnect the spark plug wires and reposition the wiring harness over the timing belt cover.
  8.  
  9. Connect the vacuum hoses, the PCV and the negative battery cable.
  10.  
  11. Start the engine and check for leaks after the engine has warmed up. Minor leaks may be cured by slightly snugging the cover bolts. Any leak that is still present after about a 1 / 4 turn CANNOT be cured by further tightening. Remove the cover again and either reposition or replace the gasket.
  12.  

 
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