Mechanics

Exhaust System Keeps Breaking

Engines utilize an exhaust system to transfer engine exhaust to the rear of the car keeping these poisonous gases from affecting the car passengers. Typically these exhaust systems are made of a durable metal such as stainless steel. All exhaust systems are subject to extreme heat, creating problems with expansion and metal fatigue. As the exhaust system heats and cools it creates additional problems with the systems sealing gaskets. These gaskets must be able to withstand movement while under pressure.

Most exhaust gaskets have incorporated metal into the design and construction. The exhaust studs and mounts are used to connect the exhaust system to the engine and undercarriage of the car. These studs and hangers are made of durable material such as grade eight strength metal and heat resistant polyurethane. When an exhaust systems breaks at any particular point, and then fails again in a short time there is an underlying cause creating the multiple failures. We have listed the most common reasons of multiple exhaust system failures.

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Checking Engine Mounts - Engine mounts are used to minimize engine vibration by isolating the engine from the car frame. These mounts are constructed by using rubber vulcanized between to metal plates with threaded studs that bolt to the engine and the frame of the car. When motor mounts fail they allow the engine to move excessively. This excessive movement exerts pressure onto the exhaust system. The exhaust system is not designed to control engine torque; this can cause the exhaust system to fail. Inspect the engine mounts for structural integrity; look for any oil, cracks or separation of the mount. Remove the failed engine mount and replace if needed. Then, repair the exhaust system and recheck engine movement.

Engine Mount
New Engine Mount (appearance will vary)

Exhaust System Fatigue - Due to the heat the exhaust system is subjected to the metal used will sometimes experience fatigue. This fatigue will cause a repaired or welded exhaust system to fail again in a short amount of time. If this condition is present in your exhaust system it will need to be replaced. Fatigue can also exist in the mounting studs that are located in the cylinder head. These studs hold the exhaust manifold to the cylinder head. If fatigue is present the stud can break and will need to be replaced. This condition exists more in heavy use applications like trucks or vehicles towing trailers.

Plugged Exhaust System - The exhaust is designed to be a free flowing system. If the exhaust does not allow the engine waste to exist the system extreme pressure is built up inside the exhaust system. This excess pressure can cause the system to fail by blowing it apart. If there is an obstruction in the system it will cause this condition. One of the more common reasons for this problem is catalytic converter failure.

Plugged Catalytic Converter from Broken Catalyst Material
Plugged Catalytic Converter from Broken Catalyst Material

Exhaust Hanger Failure - An exhaust hanger is designed to support the exhaust system as it hangs below the car. If these hangers are missing or broken it will cause the exhaust system to break due to the added stress put on the system. Inspect the exhaust hanger supports and replace them as needed.

Exhaust System Supported by Hangers
Exhaust System Supported by Hangers

Non-Stainless Steel Exhaust Systems - Not all exhaust systems are made of stainless steel, some are made of regular mild steel, which is susceptible to rust. This rusting will erode your exhaust system from the inside, so it isn’t readily noticed on inspections, and can’t be repaired due to the lack of integrity in the metal. If this is the case with your car, your exhaust system will need to be replaced.

If further assistance is needed, our certified car repair technicians are ready to answer your car questions.

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AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-08-16)