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The ultimate guide to exhausts

Ellie Dyer-Brown, 7 months ago

2 min read

  • Advice
  • Maintenance
Mechanic checking car exhaust

WhoCanFixMyCar answers all your questions relating to exhaust systems, including how to fix them and how much this is likely to cost.

Exhausts play a vital role in directing harmful gasses and pollutants away from passengers and out of the tailpipe. If there’s an issue with your exhaust - such as a hole in the system - the chances are, you’ll know about it. These types of problems are often very loud and accompanied by the strong smell of exhaust fumes where they shouldn’t be - in the cabin. 

Naturally, if there’s a problem with your exhaust, you’ll want to get it fixed as soon as possible. But what could be going wrong, and will it cost much to fix? These are among the most popular questions related to car exhausts. 

In this guide, WhoCanFixMyCar is going to attempt to answer all the queries you might have about this topic, so whether you’re going to the garage or attempting an at-home fix, you can do so with confidence


How much does it cost to fit a new exhaust?

How long does it take to fit a new exhaust?

Does exhaust repair putty work?

Do electric cars have exhaust pipes?

How to repair a cast iron exhaust manifold

How to fit an exhaust back box

How to repair a scratched chrome exhaust

How to repair a hole in the exhaust pipe

How much does it cost to fit a new exhaust?

On average, having an exhaust fitted costs £125.06 when booked through WhoCanFixMyCar. 

It’s worth mentioning that some exhaust problems can be repaired without the need for replacing the whole system, and this will usually work out much cheaper.

How long does it take to fit a new exhaust?

The most common part of the exhaust system that is replaced is the rear box, which can take anything from thirty minutes and an hour. Other exhaust components take a lot longer to replace - for the whole system, your car could be in the garage for a day or more.

Does exhaust repair putty work?

For those who don’t know, repair putty - sometimes called exhaust paste - is designed to provide gas-tight seals for joints and holes in the exhaust system. It can be used to successfully seal up small holes and leaks, but any significant damage or corrosion will need more serious attention from a professional.

Do electric cars have exhaust pipes?

Since electric cars don’t run on fuel, no combustion takes place in the engine, which means there are no harmful gases to get rid of using an exhaust.

How to repair a cast iron exhaust manifold

To repair a damaged exhaust manifold will require a certain amount of skill as well as welding ability. If you’re not confident in carrying out car repairs yourself, you can use WhoCanFixMyCar to find a reliable local garage to do it for you.

However, if you want to proceed with repairs yourself, follow these steps.

  • Remove the damaged manifold by taking out the bolts that hold it in place. As long as the crack isn’t too wide it should be possible to solder it.

  • Scrape off any worn down gasket parts and clean the area.

  • Bevel the edges of the crack to no more than 1/16 inch (make sure you’re wearing safety equipment!).

  • Take the manifold to a workstation. Set the welding torch or soldering iron and place the tip of the silver solder against the crack. You should use a size one tip solder and hold the torch very near to melt it onto and into the crack. Continue until the crack is filled.

You should be aware that repairing your exhaust manifold this way is only a temporary fix and you should have a full replacement carried out as soon as you can afford to do so.

How to fit an exhaust back box

Before we explain how to fit an exhaust back box, let’s first take a moment to discuss what one actually does. The back box slows down the fast moving gases that travel through the exhaust at a high temperature. This helps to ensure your vehicle runs both quietly and smoothly. 

To fix this part of your exhaust, you will need a saw, hammer, spanner or socket set, a car jack and two jack stands. Then follow the steps below. 

  • Jack your car up on a dry and level surface.

  • Find your exhaust’s back box - it should be located between the rear axle and catalytic converter.

  • Using a spanner or deep socket, start removing the bolts that hold the back box in place.

  • Next, use a saw to cut away the pipes in front and behind of the silencer. 

  • Remove the hanger that holds the silencer.

  • Attach the exhaust pipes, allowing them to slip into place. Slide clamps up both ends of the pipe and apply plenty of sealant. 

  • Move the silencer onto the ends of the exhaust pipes and move the clamps into place.

  • Use the hanger to reattach the part to the car in much the same way you took it off.

How to repair a scratched chrome exhaust

Chrome plating is very thin, so it’s almost inevitable that it will develop scratches and scrapes at some point or other. Thankfully, fine scratches can easily be removed by following these instructions. 

Find a polish that’s specifically designed for chrome and apply it to a steel wool pad or soft cloth. Using circular motions, rub the cloth or pad over the affected area. Apply more polish as necessary and continue rubbing for several minutes. 

Next, use a microfiber cloth to remove the polish before inspecting the area. If you can still see the scratches, repeat this process until they are gone. However, be aware that some deeper scratches will require re-plating to get rid of them.

How to repair a hole in the exhaust pipe

If there’s a small hole in your exhaust pipe that’s easily accessible, you might be able to repair it yourself. To do so, you’ll first need to decide whether to use muffler repair tape or exhaust putty. The difference between the two is that tape provides an almost instant fix, whereas putty takes much longer to dry. 

To locate the hole, you’ll firstly need to jack your car up so you can see the source of the problem more clearly. Make sure that the area around the hole is clean to ensure the repair works properly and lasts. 

Using Tape

If it’s less than twenty degrees outside, let the engine run for a bit to warm it up. The tape will stick to warm metal more easily. 

Next, turn off the engine (don’t let it get too hot or you could burn yourself) and remove the backing from the tape. It’s a good idea to wear gloves while you apply the tape to prevent any burns. Wrap a few pieces of wire around the tape to secure it properly. 

Finally, let the engine run for twenty minutes to fuse the tape to the exhaust.

Using putty

After you’ve cleaned the area, dampen it with a cloth. Spread the putty around the hole, making sure that it’s filled up as well as covered. Let the engine idle for around ten minutes. 

Once applied, you shouldn’t drive your car for twenty four hours to give the putty time to dry. 

It’s important to remember that both of these methods are temporary fixes; you should still get your exhaust repaired by a professional as soon as you’re able to do so.