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.
Car Repair Guide
Checking 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.
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
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
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
Non-Stainless Steel Exhaust Systems
- Not all exhaust systems
are made of stainless steel, some are made of regular
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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Article first published 2009-08-03 (Updated 2015-01-06)