How to Clean Your Exhaust System – Inside and Out

An exhaust system is an essential component of any car on the road, not only does it expel harmful gases from your vehicle, it also converts them to less harmful gasses, as well as reducing noise pollution. Proper maintenance of your exhaust system parts and components will ensure optimal performance and functionality.

This guide will be split into 3 sections: Exhaust pipes and exhaust exterior, cleaning the catalytic converter and cleaning the exhaust manifold.


As your exhaust releases carbon dioxide, small amounts of gasses fuse inside your exhaust pipe, coating it black. This build up looks dirty and ugly, but it also decreases the overall performance of your exhaust system, as the congestion can interrupt the flow of gasses from your vehicle.

As well as carbon dioxide buildup in the exhaust pipes, rust is another thing that can damage your exhaust.

During the combustion process of the engine, water is created as a byproduct and finds its way out through the exhaust pipes. This is a completely normal part of the combustion process and seeing water drip from your tail pipe is nothing to be alarmed about. But when the engine is switched off, or if you only drive short trips, moisture remains in the exhaust and can rust the exhaust pipes.

The only way to truly prevent rust in and on your exhaust is by upgrading to a stainless steel exhaust system, which won’t rust or suffer from carbon buildup. Maintaining a stainless steel exhaust system is very easy and only requires simple cleaning with soap and water from time to time.

Using Soap and Water Clean the Exhaust Pipe
Cleaning the exhaust pipe with soap and water is the first step in bringing a corroded exhaust pipe back to life. Using a cloth, clean the exhaust tip, then for inside the exhaust, use a hard bristled brush, cleaning as deep in the tail pipe as you are able to.

Applying a degreaser will help in breaking up carbon deposits and rust. Using a dry cloth, apply a degreaser to the inside and outside of the exhaust. The package of the degreaser of your choice should indicate how long the degreaser should be left on for. Allow the degreaser to sit for this period of time, then using steel wool, scrub the degreaser off, working in circular motions.

Apply Polish
Using a microfiber cloth, wipe down the exhaust to remove dust and moisture. After this is done, using some steel wool, apply a metal polish to the inside and outside of the exhaust tip.

The polish should be left to sit for the recommended time on the polishes packaging, then, using a microfiber cloth, buff the polish off of the surface.


If your exhaust is failing an emissions check, it’s likely your catalytic converter may be the cause of this. Catalytic converters remove dangerous particular matters before they exit the tailpipe, over time, this part can become clogged with carbon build up and requires cleaning.

While cleaning the exhaust pipe is quite simple, cleaning the catalytic converter is much more involved. Please note that cleaning the catalytic converter is not recommended by vehicle manufacturers, there is a possibility of the internal catalyst being damage, effectively ruining the whole system. It is highly recommended to have a professional mechanic clean your catalytic converter as to avoid any problems that may arise otherwise.

With that being said, we will guide you through the process of cleaning the catalytic converter, without removing it.

Diagnosing the Issue
Purchase an OBD-II scanner. These are made to analyze issues communicated by the check engine warning light.

Under the dashboard of your vehicle, you should find an OBD-II port, plug your OBD-II scanner into this port. If you are having trouble locating this port, please refer to your vehicle owner’s manual, but it is usually found underneath the steering wheel.

Without starting the ignition, turn the key of the car, turning the electricity on, this will activate the OBD-II scanner. Allow some time for the device to boot up.

Enter in the car’s make, model and VIN number. The reader will generate a trouble code. Make sure you write this down, then search the trouble code online or in your car’s owner’s manual to see if the catalytic converter is the cause.

Cleaning Your Catalytic Converter
There are a few things to consider before attempting to clean your catalytic converter.

A catalytic converter can become so clogged that the engine is not able to run anymore, if this is the case, you will need to replace the catalytic converter, or have it fixed by a mechanic.

Before you begin cleaning the catalytic converter, you need to check if there are any loose parts inside. Checking for this is fairly straightforward, you can check by simply hitting it with a hammer and listening to see if you can hear any loose parts rattling around. If you do hear loose parts, the catalytic converter should be removed, inspected further and taken to a mechanic to fix it.

If there are no loose parts, you can begin the catalytic converter internal cleanse. There are many catalytic converter cleaners on the market, so you can do your research to find the one which you think will be most suitable.

Wait until your gas tank reaches about 4 gallons of gas. This figure will vary between different cleaners, so please check the directions on the label. Pour the cleaner into the gas tank—make sure to follow the directions on the packaging, as some brands instruct the whole bottle to be used, whereas others specify to only pour part of the bottle in.

Now drive your car as normal until near empty, then fill it up with gas as you normally would.

If after the cleanse and the check light returns, please take your car to a mechanic immediately for further inspection.


Every combustion engine has an exhaust manifold, it collects exhaust from the engines cylinders, pulling it away from the engine. Over time, exhaust manifolds get covered with carbon buildup, soot, grease and rust. When this happens the manifold loses efficiency and affects the overall performance of the vehicle.

Your exhaust manifold should be cleaned every now and then, here is our how-to-guide on cleaning your car’s exhaust manifold.

Remove the Manifold
Check your owner’s manual to locate your cars manifold. Remember that 4 cylinder cars have only a single manifold, but 6 and 8 cylinder vehicles have 2 manifolds.

Make sure the engine has been switched off for at least 30 minutes and is cool to the touch.

Before you start removing the manifold, be sure you are working safely by wearing gloves, safety glasses and a dust mask.

Remove the hoses which are attached to the manifold, then, using some WD40, spray the bolts on the manifold heat shield. Remove the bolts. After the bolts have been removed, you can remove the exhaust manifold.

Using a lacquer thinner, soak the interior of the manifold. Using steel wool and a wire brush, scrub the manifold exterior, paying special attention to coated spots. Wipe the entire manifold with the lacquer, let it sit for a while.

After the manifold has been cleaned, you simply need to reattach it to the engine.

Daniel Calvin is the blog writer for Capristo Automotive, sharing high torque content in the sports car world.

Editor’s Note: The opinions expressed in this article are those of the author.

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One Response to “How to Clean Your Exhaust System – Inside and Out”

  1. Joe Allen says:

    You forgot one important component of the exhaust, that is the oxygen sensor. Any condition causing the motor to run hot coats the sensor with a black carbon soot which causes the motor to run rich, which puts more carbon on the sensor, etc. I don’t know how you clean one, but if the sensors have quite a few miles on them, replacement is a great idea, and can save fuel.