How To Fix An Exhaust Leak – A Step By Step Guide

How to Find an Exhaust Leak and How To Fix It…

How to Fix An Exhaust LeakExhaust leaks can cause a lot of issues with your vehicle. When you have a leak in your exhaust you may hear a lot of noise, notice an increase in your gas usage, and it may cause your “check engine” light to come on (which is always a worry).

If your vehicle has a big leak it could fill the inside of the car with carbon monoxide, which can cause you and your passengers to become very ill.

For this reason, it’s important to find exhaust leaks quickly and to have them fixed as soon as possible.

How to Find an Exhaust Leak

There are several methods that can be used in to find an exhaust leak. Here are a few tips on how to find an exhaust leak in your vehicle.

First, make sure that your car is parked on a surface that is firm and level such as on concrete or blacktop.

Next, make sure that the vehicle is in park and the parking brake is engaged.

Once the car is in place you will want to start the vehicle in order to find out where the leak is coming from.

From under the vehicle you will want to look for puffs of smoke throughout the entire exhaust system.

how to find an exhaust leakThis includes from the engine all the way back to the tail pipe. Wherever you see smoke escaping there is a leak.

When you are working under a running vehicle you must be very careful and keep your hands away from any working parts.

Aside from smoke you should also look for any signs of damage such as rust, cracks, scrapes, or holes.

In vehicles that sit lower to the ground leaks may be caused by the underside of the vehicle bottoming out on potholes or speed bumps.

And of course another common cause of leaks is rust, so make sure you have a good look for this too.

Check out our exhaust leak symptoms guide for more help in locating leaks.

Assessing the Damage

When you are under the vehicle it is important to assess the type of damage and the extent of it.

Repair options will vary based on the type of damage that you find.

how to find an exhaust leakIf your exhaust piping has a large amount of rust on it, the entire exhaust component may need to be replaced by a professional.

If there is just a small scrape or hole, it may be repaired using repair putty or exhaust tape.

A larger hole will need to be covered with aluminium and then sealed with an epoxy.

How to Fix An Exhaust Leak

Option 1 – Using Exhaust Tape or Repair Epoxy for Patching a Leak

Once you have located the leak it is time to repair it.

  1. First, make sure that you turn the vehicle off and wait for the exhaust to cool. This can take some time.
  2. Once the exhaust is cooled, you will want to use a steel brush to clean the area around the leak.
  3. Make sure to wear some type of protective eye ware so that the dirt doesn’t fall into your eyes while you scrub.
  4. Next, take some sandpaper and rough up the area of the pipe that you are going to repair. The sandpaper helps remove all the bits of dirt and will create small grooves in the metal that will help the epoxy or tape to stick to it.
  5. You will then need to use acetone to wipe down the area that you’ve just scrubbed and sanded. (If you do not have any acetone to hand you can use nail polish remover instead).

How to Fix An Exhaust LeakIf the hole is small enough you might not need to use a patch. A small pinhole or a tiny crack can be sealed by using either exhaust tape or epoxy.

If the hole is much larger than this you will need to use a patch.

Option 1a – Exhaust Tape

If you’re using exhaust tape for the repair make sure that you wrap the tape all the way around the area where the leak is located.

Wrap the area with at least two layers of the tape. Also, to be safe, make sure that the tape is wrapped around the pipe a few inches on either side of the leak as well.

This will result in a more stable repair.

There are different types of exhaust tape available so it is important to read the instructions on how to apply the type of tape that you have purchased.

Here’s a handy clip from Scotty Kilmer on how to fix an exhaust leak using tape:

Option 1b – Epoxy

If you are using epoxy in order to seal the leak in your exhaust you will want to use a dowel to mix the two parts together.

Once you have mixed up the epoxy it will start to bind straight away so you will need to act fast.

Take the epoxy and paste it over the hole or the crack then use the dowel to spread it over the surface of the pipe around the leak.

You should leave a generous layer of the epoxy over the area of leak.

After applying the epoxy you might want to wrap the area in tape as well.

The amount of time the epoxy will take to set completely will depend on the brand that you purchase, so make sure to read the directions and wait the appropriate amount of time afterwards before driving again.

J-B Weld is a good epoxy that comes highly recommended.

Option 2 – Using a Patch to Repair a Leak

If the hole that you are repairing is larger, you will need to use a patch.

There are exhaust patch kits available at any local auto parts store. You can also use an aluminium can as a patch.

How to Fix An Exhaust LeakOnce again you will want to scrub and clean the area around the leak thoroughly.

  1. You should then measure the hole and cut your patch so that it is about a half an inch to an inch larger than the hole that you’re repairing.
  2. If the hole in the exhaust is bigger than 3 inches it is likely that you will want to replace that entire portion of the exhaust.
  3. Once you have cut the aluminium patch to fit over the hole (or if you are using a can, cut it in half so that it will cover the area), you will want to wrap it around the pipe to test that it fits well and will therefore provide a good seal.
  4. Make sure that you use gloves when you are cutting the aluminium as it will have sharp edges and you do not want to cut your fingers or hand.
  5. If you’re happy with the size and shape of your patch, remove it from the hole and then mix up your epoxy.
  6. Once the epoxy is mixed, use it to cover the entire area where the patch will go. Use the epoxy in the same way as you would for covering a small hole (described above).
  7. The epoxy will help to hold the patch in place. When you are applying the epoxy you need to make sure that you use enough to create a seal for the patch, but do not use so much that it leaks into the exhaust itself.
  8. The epoxy should be applied to the area that surrounds the leak and be about equal to the size of the patch that you’ve cut out. If you are attaching the patch all the way around the pipe, apply the majority of the epoxy to the area where the leak is located and a light coat all the way around the pipe where the patch is to go.
  9. Next, take the patch and place it over the hole in the exhaust. You may place the patch directly over the hole or you can wrap a larger patch around the entire pipe.
  10. If you choose to wrap the patch around the pipe make sure that the middle of the patch covers the hole.
  11. When you are applying the patch some of the epoxy may leak out the sides.  This is fine.  Just make sure that the leak is entirely covered by the patch.
  12. Once  in place you should apply a little more epoxy over the edges of the patch (or completely cover it if you wish).  This helps to secure the patch in place and creates a more solid seal to prevent any exhaust leakages in the future.

If the patch that you have used is big, use a hose clamp to secure it in place. If the patch goes all the way around the pipe, you could use a couple of clamps to keep it secured in place.

How To Fix An Exhaust Leak – Conclusion

The exhaust of your vehicle is extremely important and the exhaust system is made up of many different parts that all work together to ensure that the fumes leave the engine and disperse out into the atmosphere rather than into the cabin of your vehicle.

For this reason it is important to make sure that your exhaust system is working properly at all times. If you start to hear a noise or feel a weird vibration, there is a good chance that you have a leak somewhere in your exhaust.

Make sure that you check for leaks regularly either on your own or by having it done by a professional.

We hope you found that helpful.

Have you fixed an exhaust leak recently?  If so, how did you get on?  Let us know below.

If you need more help check out this short guide by Autozone.

For bigger jobs you can find the best welder for exhausts in our comprehensive welding guide.


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