GM Prizm/Nova 1985-1993 Repair Guide

Special Tools

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A number of special exhaust system tools can be rented from auto supply houses or local stores that rent special equipment. A common one is a tail pipe expander, designed to enable you to join pipes of identical diameter.

It may also be quite helpful to use solvents designed to loosen rusted bolts or flanges. Soaking rusted parts the night before you do the job can speed the work of freeing rusted parts considerably. Remember that these solvents are often flammable. Apply only to parts after they are cool!

The exhaust system of the Nova and Prizm consists of 4 pieces. At the front of the car, the first section of pipe connects the exhaust manifold to the catalytic converter. On Prizm models, this pipe contains a section of flexible, braided pipe. The catalytic converter is a sealed, non-serviceable unit which can be easily unbolted from the system and replaced if necessary.

An intermediate or center pipe containing a built-in resonator (pre-muffler) runs from the catalytic converter to the muffler at the rear of the car. Should the resonator fail, the entire pipe must be replaced. The muffler and tailpipe at the rear should always be replaced as a unit.

The exhaust system is attached to the body by several welded hooks and flexible rubber hangers; these hangers absorb exhaust vibrations and isolate the system from the body of the car. A series of metal heat shields runs along the exhaust piping, protecting the underbody from excess heat.

When inspecting or replacing exhaust system parts, make sure there is adequate clearance from all points on the body to avoid possible overheating to the floorpan. Check the complete system for broken damaged, missing or poorly positioned parts. Rattles and vibrations in the exhaust system are usually caused by misalignment of parts. When aligning the system, leave all the nuts and bolts loose until everything is in its proper place, then tighten the hardware working from the front to the rear. Remember that what appears to be proper clearance during repair may change as the car moves down the road. The motion of the engine, body and suspension must be considered when replacing parts.

COMPONENT REMOVAL & INSTALLATION



See Figure 1


CAUTION
DO NOT perform exhaust repairs with the engine or exhaust hot. Allow the system to cool completely before attempting any work.Also, exhaust systems are noted for sharp edges, flaking metal and rusted bolts. Gloves and eye protection are required. A healthy supply of penetrating oil and rags is highly recommended.

ALWAYS use a new gasket at each pipe joint whenever the joint is disassembled. Use new nuts and bolts to hold the joint properly. These two low-cost items will serve to prevent future leaks as the system ages.

Front Pipe
  1. Elevate and safely support the vehicle on jackstands.
  2.  
  3. Disconnect the oxygen sensor.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Nova exhaust system

  1. Remove the 2 bolts holding the pipe to the exhaust manifold.
  2.  
  3. Remove the 2 bolts holding the pipe to the catalytic converter.
  4.  
  5. Remove the bolts from the crossmember bracket and remove the pipe from under the car.
  6.  
  7. Attach the new pipe to the crossmember bracket. Install the bolts at both the manifold and the catalyst ends, leaving them finger tight until the pipe is correctly positioned. Make certain the gaskets are in place and straight.
  8.  
  9. Tighten the pipe-to-manifold bolts to 46 ft. lbs.
  10.  
  11. Tighten the bolts at the converter to 32 ft. lbs.
  12.  
  13. Reconnect the oxygen sensor.
  14.  
  15. Lower the vehicle to the ground, start the system and check for leaks. Small exhaust leaks will be most easily heard when the system is cold.
  16.  

Catalytic Converter

With the car safely supported on jackstands, the converter is removed simply by removing the 2 bolts at either end. The Nova models have an air suction pipe attached to the converter which must be disconnected (2 bolts) before removal. When reinstalling the converter, install it with new gaskets and tighten the end bolts to 32 ft. lbs. Reconnect the air suction pipe (Nova) and lower the car to the ground.

Intermediate Pipe (Resonator Pipe)
  1. Elevate and safely support the vehicle on jackstands.
  2.  
  3. Remove the 2 bolts holding the pipe to the catalytic converter.
  4.  
  5. Remove the bolts holding the intermediate pipe to the muffler inlet pipe.
  6.  
  7. Disconnect the rubber hangers and remove the pipe.
  8.  
  9. Install the new pipe by suspending it in place on the rubber hangers. Install the gaskets at each end and install the bolts finger tight.
  10.  
  11. Double check the placement of the pipe and insure proper clearance to all body and suspension components.
  12.  
  13. Tighten the bolts holding the pipe to the catalytic converter to 32 ft. lbs., then tighten the bolts to the muffler inlet pipe to 32 ft. lbs.
  14.  
  15. Lower the car to the ground. Start the engine and check for leaks.
  16.  

Muffler and Tailpipe Assembly
  1. Elevate and safely support the vehicle on jackstands.
  2.  
  3. Remove the 2 bolts holding the muffler inlet pipe to the intermediate pipe.
  4.  
  5. Disconnect the forward bracket on the muffler.
  6.  
  7. Disconnect the rear muffler bracket (3 bolts) and remove the muffler from under the car.
  8.  
  9. When reinstalling, suspend the muffler from its front and rear hangers and check it for correct positioning under the body. If the old muffler had been rattling or hitting the body it is possible that the hangers and brackets have become bent from a light impact.
  10.  
  11. Attach the inlet pipe to the intermediate pipe and tighten the bolts to 32 ft. lbs.
  12.  
  13. Lower the vehicle to the ground, start the engine and check for leaks.
  14.  

Complete System

If the entire exhaust system is to be replaced, it is much easier to remove the system as a unit than remove each individual piece. Disconnect the first pipe at the manifold joint and work towards the rear removing brackets and hangers as you go. Don't forget to disconnect the air suction pipe on the Nova catalytic converter. Remove the rear muffler bracket and slide the entire exhaust system out form under the car. The new system can then be bolted up on the workbench and easily checked for proper tightness and gasket integrity.

When installing the new assembly, suspend it from the flexible hangers first, then attach the fixed (solid) brackets. Check the clearance to the body and suspension and install the manifold joint bolts, tightening them to 46 ft. lbs.

 
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