Table of Contents
- The History of the Muffler
- How a Muffler Works
- How Can I Tell My Muffler Has a Problem?
- Why Do Mufflers Develop Holes and Cracks?
- How to Repair a Muffler
- Should I Even Bother Repairing the Muffler?
- How to Replace a Muffler
The muffler is the proper name for that box at the end of your exhaust. Its purpose is to reduce the noise levels coming out of your exhaust. In most countries around the world, these noise restraints are placed on vehicles to keep residents and pedestrians happy. Although it takes away the fun for a petrolhead to get the biggest roar possible out of their car, everyone else should be content in the long run.
In this article, we will look at the history of the muffler, how it works, and how to repair or replace it, should you need to. If you want to jump to a particular section, feel free to scroll down until you get to the relevant subheading.
We hope you find this article interesting and useful.
The History of the Muffler
The exhaust muffler was first patented in 1897 by Milton and Marshall Reeves. Since that time, the muffler has become more and more advanced at reducing noise. Other sections have also been added to the exhaust, such as the catalytic converter, patented in the 1960s, reducing the number of harmful gasses a car puts out into the atmosphere.
The catalytic converter is also sometimes referred to as a catalytic muffler. This shouldn’t be confused with the standard exhaust muffler we are looking at today.
The exhaust muffler that we’re examining in this article is also sometimes known as an exhaust silencer because it silences noise. Clever.
As we mentioned in the introduction, for much of the last hundred years, developed countries have put stringent restrictions on the use of mufflers in cars. The purpose of these laws has been to keep levels of noise pollution as low as possible.
The best places you can go to hear real engine-and-exhaust noise – without mufflers – is a racetrack. Here, there are (usually) much less strict noise restrictions, and the cars will be fitted out with anything that makes them go as fast as possible. And often, in the world of auto racing, more speed equals more noise.
How a Muffler Works
As we have seen from the previous section, a muffler or a silencer reduces the amount of noise output from an exhaust system.
A standard car engine is essentially a continuous series of high-intensity explosive reactions, with anywhere between 600 and 10,000 revolutions per minute (depending on your vehicle). This can produce what some people would refer to as an extremely excessive volume. Others – petrolheads and the like – enjoy the noise, but since you need to have a muffler in most developed countries around the world, this isn’t much of an option for them.
If you were to dissect a muffler box, you would find a couple of strangely simple tubes. There’s nothing too complicated here.
Mufflers work by using the principle of “destructive interference.” This is the scientific principle of two sound waves colliding with each other and therefore canceling each other out. There will also likely be some kind of sound-absorption material included in the muffler, such as fiberglass. When the sound waves go through this, it works to “deaden” the noise. In technical terms, it reduces the amplitude of the sound waves.
How Can I Tell My Muffler Has a Problem?
Here, we will run through a list of quick potential issues with a muffler, and how to tell if something’s badly wrong with it.
- There’s a hole in it – Well, it doesn’t take a genius to work out that this isn’t exactly the ideal situation. If you can see an obvious hole in the muffler, you should repair it. You might notice this if you’re ever looking at the car from underneath. This includes when it’s over an inspection pit or up high on an automotive ramp. You might also notice it from simply bending down behind the car and having a quick look. Holes like this are usually caused by general wear and tear as the metals degrade and rust. On occasion, they could be caused by sudden knocks, such as speed bumps, potholes, or debris that’s thrown up from the road.
- Your exhaust sounds louder – When there is a hole in the exhaust, it will certainly sound louder, but more than that – perhaps also somewhat “out of tune.” You will know your car better than anyone else – you’ll be familiar with the general noise it makes. Therefore, if you think that there’s something not quite with the noise being produced, but can’t quite put your finger on it, the muffler should be one of the first things you check out.
- Loud vibration sounds coming from the rear of the car – Hopefully, this will just be your muffler. If it’s not, you have a potentially very serious problem.
- Your car occasionally loses power or struggles and jumps a bit – While this could be a cause of many things, one of the possible reasons is a damaged muffler.
- Reduced fuel economy – If your tank seems to be emptying quicker than usual, again, this could be a symptom of many things. One of them, however, could be a damaged muffler.
We’ve listed these problems from the clearest symptoms of a damaged muffler to the more subtle ones.
It should be noted, as well, that sometimes your muffler can be very subtly damaged. There isn’t always a gaping hole in the side somewhere. Sometimes there could be a hole, but it could be only the size of a pin or a hairline crack. That doesn’t mean there’s no problem – just that it’s more difficult to spot.
Why Do Mufflers Develop Holes and Cracks?
Although sometimes they can be hit by parts of the road, such as potholes or speed bumps, the most common cause of these damages is simply the muffler starting to go “rotten” on the inside.
This part of the exhaust deals with exhaust gases as long as the car engine is switched on. These exhaust gases are also full of moisture. Over time, your muffler will inevitably begin to rust. This almost always happens from the inside out.
How to Repair a Muffler
Repairing a muffler is one possible approach you might take if you find a problem with it. This is especially easy if the damage is a small exterior hole.
You should know, though, that repairing a muffler is rarely a long-term fix. You should look into getting the whole part replaced when you can. It’s difficult to repair an exhaust so that it will last for a long time.
Method 1 – Exhaust Tape
The simplest way to repair a small hole in a muffler is to use a special type of tape. Conveniently, this type of tape is called exhaust tape.
If you’re going to use this method, the hole or crack you’re patching must be relatively small. By this, we mean thin cracks and holes not much bigger than a pinhead. If you try to use exhaust tape to cover anything larger than this, you’ll find that it will leak again after a few hours of driving. This is because the exhaust gases are being forced out of the hole with energy stronger than the adhesive stick of the tape, and they will simply find a way through it.
However, if the hole is small or the crack is particularly thin, this is a valid approach, and you will be able to get it done yourself with little effort and little cost.
- Use a wire brush to remove the big bits of rust and debris from the exhaust muffler’s outer shell. You can pick these up for next to nothing at any parts store. It doesn’t have to be anything fancy – all you want to do is begin to clean off the surface. It doesn’t have to look nice. Scrub all around the hole and the substantial area around this as well. This includes where you’re going to need to stick the tape. Ideally, you will need to wrap the tape all around the muffler, so it’s best to clean as much of this surface area as possible.
- After using the wire brush, use some sandpaper to remove the last bits of dirt and create small abrasions in the metal. This will help the exhaust tape stick to it. Again, scrub all around the muffler if you can.
- Next, wipe the entire surface you’ve just cleaned down with acetone. This makes it a little easier for the exhaust tape to stick. Make sure that you wear appropriate PPE when working with acetone, taking extra precautions to not get it in your eyes or on your skin.
- Wrap the tape around the muffler, covering the hole with at least two layers. You will also need to cover the areas immediately surrounding the crack or hole. Because the muffler is quite large, you will be using quite a lot of tape. Different types of tape need to be applied in different ways (for example, for some, the exhaust will need to be hot; for others, you will need to wet the tape first; and so on) – so make sure you read the relevant instructions for this.
- You may also like to seal the leak with epoxy. You could choose to apply the epoxy before the tape if this works better for you, too.
Method 2 – Patch and Electrical Tape
This method is the same as the previous one, but should be used if the hole or crack you have is a little larger.
- Use the same methods as detailed above to clean the area around the muffler, as well as the top and bottom, and anywhere you will be wrapping tape. Use the wire brush, sandpaper, and acetone to prepare the area.
- Instead of directly applying the tape, though, on this occasion, you should get a piece of metal that snugly fits over the damaged area. If your muffler’s side is curved, cutting out the side of a soda can do the job.
- You should then use the tape in the same way as detailed in the previous method to ensure that this “patch” is held in place nicely.
- It might also be a good idea to make sure the area is sealed correctly with epoxy. You may want to apply this before the patch.
Method 3 – Welding
It may technically be possible the weld the crack or hole closed too, but you would be more likely to create more of a hole. Because the inside of the muffler is likely all rusting, and it’s not possible to weld this, you wouldn’t accomplish much.
However, if you have a relatively new muffler, then you might be able to weld something like this. For the best results, though, make sure that you use a professional welder that can be adjusted to work on thin stainless steel. Cheap welders aimed at DIYers and hobbyists are more likely to just go straight through the metal.
If you’re set on welding, feel free to give it a go, but we wouldn’t rest any high hopes on this method. It’s much more expensive than using a patch or just exhaust tape and is less likely to work. For that reason, we wouldn’t recommend it.
Should I Even Bother Repairing the Muffler?
If you’re a bit short on money, then it might be a good idea to repair the muffler in one of these ways.
However, the brutal reality is that none of these are long term fixes. You shouldn’t expect exhaust tape to last more than 3 or 4 months before the leak opens up again, and you begin to notice the symptoms a second time. This is because the problem usually stems from internal rust inside the muffler. There is no real way to stop this – the part is expected to be perishable over a few years. You will eventually need to replace it.
In the end, we would always recommend a replacement muffler as soon as possible. We will go into how to do this yourself now. Otherwise, it should be a relatively simple job for a garage to do for you.
How to Replace a Muffler
The muffler is usually a component in one with the tailpipe – the bit that sticks out of the back of your car. On some cars – especially older cars – you might find that the entire exhaust pipe – from the front of the car to the back – is all one component. In this situation, you may be able to purchase an aftermarket tailpipe (including the muffler), cut the exhaust at the appropriate place, and use a clamp or a sleeve, with some silicone, to hold it in place. In many cases, though, you’ll have to replace the whole pipe. Although it might be more expensive, you can expect that to be a simpler job.
Assuming that the tailpipe and muffler are an individual piece, you would replace it like so:
- Jack the car up at the rear on safe, level ground. Make sure the ground is solid – for example, asphalt or concrete – rather than soft or slippy, such as gravel, grass, or icy roads. Put axle stands under the car. Never work on a car that is only held up by a jack, as on occasion, jacks will fail. If you have access to an auto ramp or an inspection pit, this will make your work much easier and safer, and we would recommend taking this route if possible.
- Ensure that the second-hand part you’ve bought matches the shape of the existing muffler and tailpipe on your car, including any brackets or mountings.
- The tailpipe will usually be connected to the mid-pipe, front pipe, or catalytic converter using a sleeve or clamp. You should be able to undo these with the correctly sized socket and ratchet. You may need some lubrication, such as WD40, and some general brute force – remember that these bolts have likely been continually exposed to water since the day they were installed, and so rust is a real potential issue.
- On occasion, it might not be possible to remove the clamp immediately, and you may have to cut the exhaust off to get the process started. If you have to cut the exhaust, use a pair of pipe cutter pliers. Never use an angle grinder or similar cutting tool – the fuel tank will be right next to where you are cutting, and a basic slip could ignite it, basically turning the car into a bomb that you’re standing or lying underneath. Pipe cutter pliers take a bit more effort but are oh-so-much safer. Once you have got that section of pipe off, remove the sleeve or clamp. You may need to use a hacksaw or some heat to prise it off.
- To install the new muffler, put the sleeve over the exhaust pipe and fix it in place, ensuring it’s safely sitting in all the mountings. You may need a second person for this
- When everything is lined up, move the sleeve over the join and seal it with some silicone. Tighten up the sleeve as much as possible using a socket of the right size.
- Double-check that everything is attached securely before lowering the car back to the ground. Easy!
There you go – that’s all there is to it.
Occasionally, you might get stuck – for example, if you can’t get the original pipe off. When you’re really stuck, it might be best to take the car to a professional mechanic, or simply call someone up who knows what they’re doing. Overall, though, you are unlikely to run into many big problems with this kind of job.
The muffler is an essential part of the car, both for legal and social reasons. Keeping your car quiet is a basic courtesy towards your neighbors, and they will appreciate it. It’s also illegal not to have one, so you don’t have much choice in the matter anyway.
Keeping it well looked after is an excellent way to make sure you keep your car healthy as well as your relationships with those who live near you.
Also, never be afraid to take your car to your local garage to get it replaced. You should expect to pay between $200 and $400 for this job to be done by them, and about $140 – $300 to do it yourself.
We hope you’ve found this article useful.