Whether your car is just used as a daily driver or if you are a car enthusiast and love performance modifications exhaust system noises can be very annoying. A leak in your exhaust system can come from a number of places and can cause varying noises that can be hard to diagnose. Knowing what to look for, and even what to listen for can assist you knowing if you have an exhaust leak and how to identify a problem. This can assist you in the repair process or at the very least it can save you some money by being an informed consumer.
Part 1 of 2: The purpose of the exhaust system
The purpose of your exhaust system is to provide a path for exhaust gases to leave the engine and make their way out from under the vehicle. This path is used to keep exhaust gases from getting into the vehicle so that they do not make you sick, and in many cases the exhaust system will make the expelled gases cleaner to prevent damage to the environment. All of these components also assist in keeping the exhaust system quiet. There are several components in the exhaust system that can fail and cause unwanted noises.
Muffler: The exhaust system muffler is typically located at the rear of the vehicle. The purpose of the muffler is to quiet down the exhaust noise by allowing it to travel through varying chambers which smooths out the flow of the exhaust. Though the muffler is the main component used to keep the exhaust quiet, it is the main part that is changed to make a car louder should you want a high performance sounding exhaust system. The muffler can develop holes in it over time due to corrosion or it has welds or connections to the rest of the exhaust system that can break causing noise.
Catalytic converter: The catalytic converter in the exhaust system is there to assist with emissions. It changes hydrocarbons into a much safer gas that does not impact the environment as much. The converter can make noise if it develops holes, if it has connector cracks, or if it fails internally.
Exhaust pipes: The exhaust pipes connect all of the exhaust components together through connecting flanges or welds. Most exhaust pipes are made of steel which will corrode over time. This corrosion can cause holes to form in the exhaust or can cause cracks due to weakening of the components.
Exhaust manifolds: The exhaust manifolds are mounted to the engine and provide a collection point for exhaust gases to accumulate when they leave the cylinder heads. The manifolds are connected to the exhaust pipes on one end and to the engine on the other. The manifold can have a bad connection causing a leak, the gasket sealing it to the engine can fail, or the exhaust manifold can crack and leak.
Part 2 of 2: What to look for in the exhaust system
When you suspect that there may be an exhaust leak there are several things that you can look for to identify the problem. If an exhaust leak continues without being repaired it can cause turn into a much larger issue causing more noise, engine running issues, and can make the driver sick from the exhaust fumes.
- Hydraulic floor jack
- Jack stands
- Rubber hose
- Wheel chocks
Step 1: Park your car on a hard, level surface and apply the parking brake.
Step 2: Place the wheel chocks around the rear tires.
Step 3: Working on one side, at a time jack up the vehicle at the factory jacking points until it is high enough to get underneath.
Step 4: Place the jack stand under the jacking point and lower the vehicle onto the jack stand.
Step 5: Repeat step 3 and 4 at each corner of the vehicle until the entire car is high enough to get underneath.
- Warning: Once the vehicle is in the air it is important that you make sure it is fully secure before getting under it.
Step 6: Start your engine and inspect the exhaust for leaks.
Visual signs of leaking exhaust: when inspecting the exhaust system look for signs of leakage. If there is exhaust leaking from any welds or connections it will usually show up as a black or white streak on the exhaust components.
Hissing noises: The most common sound that comes from an exhaust leak is a hissing noise. It typically sounds like a small leak of air from a balloon. While the engine is running you can check all of the parts and connections of the exhaust for this noise. In many cases using a small rubber hose like a stethoscope will help to identify the leak. With one end of the hose to the exhaust and the other to your ear, you can move the hose around the exhaust until you can pinpoint the noise. Most small leaks can be repaired by tightening up loose connections or by having hose and broken welds re-welded.
Ticking or knocking noises: When a large leak in the exhaust forms it typically sounds like a loud tick or knock. Most of the time these will occur near the engine or at the exhaust manifold. Check for leaks and cracks visually and use the rubber hose to pinpoint the leak. Loud ticking and knocking noises most commonly occur at the exhaust manifold as a result of a crack in the manifold or a leak in the manifold gasket.
Your Check Engine Light can also come on if you have an exhaust leak. Leaks in the exhaust system can cause various sensors to read incorrectly causing the light to illuminate as well as causing engine drivability problems.
Any exhaust leaks should be fixed as soon as possible. Small holes and cracks in the pipes and connections can usually be repaired by welding over the leaking areas. Cracks or holes in the manifolds, the catalytic converter in the muffler would require that those components be replaced.
It is important to be vigilant of the hot components of the exhaust system when inspecting it as you can easily burn yourself. If you feel like this is beyond what you would like to do then you should enlist the help from a certified mechanic than can check your exhaust for you.
This article originally appeared on YourMechanic.com as How to Silence Car Exhaust and was authored by Robert Tomashek.