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Exhaust System


Exhaust system components are subject to both physical and chemical damage. Any physical damage to an exhaust system part that causes a partially restricted or blocked exhaust system usually results in loss of power or backfire up through the throttle plate(s). In addition to improper engine operation, a blocked or restricted exhaust system causes increased noise and air pollution. Leaks in the exhaust system caused by either physical or chemical (rust) damage could result in illness, asphyxiation, or even death. Remember that vehicle exhaust fumes can be very dangerous to one's health.

Most parts of the exhaust system, particularly the exhaust pipe, muffler, and tailpipe, are subject to rust, corrosion, and cracking. Broken or loose clamps and hangers can allow parts to separate or hit the road as the car moves.

During all exhaust inspection and repair work, wear safety glasses or equivalent eye protection.

To perform a complete exhaust system inspection:

  • Before doing a visual inspection, listen closely for hissing or rumbling that may indicate the beginning of exhaust system failure. With the engine idling, slowly move along the entire system and listen for leaks.
Be very careful. Remember that the exhaust system gets very hot. Do not get your face too close when listening for leaks.
  • Safely raise the vehicle.
  • With a flashlight or trouble light, check for the following:
    • Holes and road damage
    • Discoloration and rust
    • Carbon smudges
    • Bulging muffler seams
    • Interfering rattle points
    • Torn or broken hangers and clamps
    • Missing or damaged heat shields
  • Sound out the system by gently tapping the pipes and muffler with a hammer or mallet. A good part will have a solid metallic sound. A weak or wornout part will have a dull sound. Listen for falling rust particles on the inside of the muffler. Mufflers usually corrode from the outside in, so the damage may not be visible from the outside. Remember that some rust spots may be only surface rust.
  • Grab the tailpipe (when it is cool) and try to move it up and down and from side to side. There should be only slight movement in any direction. If the system feels wobbly or loose, check the clamps and hangers that fasten the tailpipe to the vehicle.
  • Check all of the pipes for kinks and dents that might restrict the flow of exhaust gases.
  • Take a close look at each connection, including the one between the exhaust manifold and exhaust pipe.
    • If you find a white powdery deposit, try tightening the bolts or replacing the gasket at the connection.
    • Check for loose connections at the muffler by pushing the muffler slightly. If the connections are loose, tighten them.
  • Catalytic converters can overheat. Look for bluish or brownish discoloration of the outer stainless steel shell. Also, look for blistered or burned paint or undercoating above or near the converter.
  • If a visual inspection doesn't identify a partially restricted or blocked exhaust system, perform the exhaust restriction test.