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Can a Muffler Be Patched? If So, How?

A close up photo of a clean car muffler in a new car.

A muffler can be patched, but the labor costs to patch it are often higher than the cost to simply have the muffler replaced.  With the rising price of auto parts, however, it may quickly become more economical to repair a muffler than to replace it.

Mufflers can be one of the more expensive parts to replace on a vehicle.  While a hole in your muffler will not directly affect the operation of your vehicle, all too often people are surprised to learn that their muffler or exhaust pipe needs to be repaired in order to pass an emission inspection.  

All too often, a hole in a muffler can mean a surprise auto repair bill of around $1,000, often for a repair that you don’t need to make your vehicle function.

Unfortunately, most mechanic shops don’t have the manpower to repair a muffler.  While the repair is relatively simple in that it doesn’t require specially made parts or precision work, it is often beyond the day-to-day capabilities of most shops.  

A muffler repair requires a mechanic to weld a patch, often requiring a separate workstation and cure time for the patch.  It is far easier to simply tear off and replace the muffler with a new part.

If you can do the work yourself, however, this repair will very quickly become a lot cheaper.  You will need to have some experience working on cars, but it is possible to get it done in your home garage.

Related: 5 Different Types of Mufflers for Cars

A Simple Repair

A mechanic checking the conditions of the muffler to find out what is wrong and needs repairing.

Start your repair by taking a good look at the muffler. You can usually do this by crawling under your vehicle.  If you have a public auto shop in your area, go ahead and lift the vehicle (it will make this a lot easier).  

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Inspect the pipe for signs of damage.  Specifically, look for small holes or cracks. If you see any holes or cracks that are less than two inches long or holes that are less than an inch in diameter, you can likely patch them with a muffler repair kit, available at just about any auto parts store.

Muffler repair kits

An exhaust pipe and toolbox with tools inside it isolated in a white background.

To use one of these kits, start by using a wire brush (these are usually included in most kits) to remove any dirt, debris, or rust from the muffler.  

Don’t get lazy on this step; if you leave any dirt or rust on the pipe it will effect how the sealant wrap will adhere to the pipe.  Ruse spots that are left on the muffler will  eventually rust through, making it difficult for the seal to last.  This will likely result in you needing to make the repair again in the future.

Next, remove the specially prepared cloth ( sometimes called a bandage) from the kit, and wrap it around the hole in the muffler.  Wrap it with the wet side down, and try to cover the area with the hole at least twice.  

Then, use the included piece of wire to secure the wrapping to the muffler.  Finally, run your car engine for about twenty to thirty minutes.  This will produce the heat necessary to bond the wrapping to the muffler pipe, essentially closing the leak.

Depending on the amount of cleaning you need to do, the total time to do a small repair like this will be around an hour.  It doesn’t take a lot of car knowledge to use one of these kits, but you will need to know how to identify your muffler and be able to get under the car and inspect it for cracks.

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BY the way, make sure the car is still wile the engine is running.  While it can be tempting to use the car since you’re running the engine, the vibrations of the car on the road, or the shock of running over any bumps or potholes, can jostle the wrapping loose.

This will result in the entire repair needing to be redone; the wrapping cannot be reused once the bonding process has started.

If you cannot do this type of repair yourself, talk to a mechanic who owns his or her own shop.   Most major chains will not want to spend the time on this type of repair.  

If the mechanic has not done them before or misses a spot during the cleaning process, odds are good that they will have to repeat the process.  

Because of the way most warranties are structured, many chain shops don’t want to deal with the hassle of having a customer come in upset that their repair isn’t right.

A private mechanic may be willing to do the repair if a customer is willing to leave their vehicle overnight or assist in the cure time by staying with the vehicle while it runs.  If you have a mechanic who is a good friend, it might be worth asking him or her to help you out.

Larger holes and cracks

A close up photo of an old and rusty muffler with large holes in it.

If the hole or crack in your exhaust pipe is too large for one of these kits to work, you’l need to perform a more complicated repair.

Remember that you need to be able to completely cover the entire opening with the wrap, plus have about an inch left over for the material to bond to the pipe.  

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If the hole or crack is too big, or if it is in a position where this won’t be possible, then you’ll need to actually replace a piece of the exhaust pipe. 

If you have never replaced a piece of piping in your vehicle then you will want to hire a mechanic for this repair.  The repair will involve removing the entire section of damaged pipe, then replacing it with a pipe of the same size.  This will most likely require a repair tech to cut the pipe and cold weld the new piece in.  

Because this is actually more labor than simply replacing the entire muffler, it is very rare that you’ll find a repair shop that is willing to give this a try.  

Most of the time, it doesn’t even make sense for the car owner to request it; the labor time of the mechanic doing this type of repair almost always costs more than the cost of a new muffler.

However, the recent lack of supply of car parts has made this type of repair more necessary for owners of some types of vehicles.  

This type of repair is becoming slightly more common, especially as more people are trying to get more miles out of their vehicles rather than replace them at today’s inflated prices.

If you’re asking a mechanic to do this type of repair, be prepared to pay just as much as you would have for a new muffler.  Remember, these repairs aren’t done to save the customer money, they’re done because there is no other choice.

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Frequently Asked Questions 

How Did My Exhaust Pipe Break?

Mufflers are constantly being inundated with acidic gasses released from the engine of your vehicle.  Over time, these acids wear down the metal in the exhaust pipe, causing rust spots.

It’s also possible for people living near oceans or other salty bodies of water to have more wear and tear on this part of their vehicle.

How much should I expect to pay for this repair?

A car mechanic welding and repairing a muffler in a zoom in photo.

Muffler repair kits typically cost between $20 and $50 in most auto repair stores, and you can do this repair on your own for free. 

f you decide to hire a mechanic to do it, expect to pay for about an hour or two of his or her time, depending on the condition of your muffler.

If you need to replace an entire section of piping, however, then you’ll probably be paying around $1000 for the complete repair, including parts and labor.

What happens if I don’t fix it?

Youll probably notice the noise your car makes right away if the hole or crack is completely open.  As this hole gets bigger, your car will et a lot louder.