Revitalize Your Ride: Ultimate Guide to Flushing Your Exhaust System

When you think of car maintenance, the exhaust system is not one of the things that comes to mind. 

But considering its role and value, it probably should be. Keeping your car exhaust system clean and unclogged ensures that it can do a proper job of expelling fumes from the combustion chamber. The technical term for this cleaning is ‘flushing’. 

Wondering how to flush exhaust system? This process involves cleaning the inside and outside of the exhaust pipes, the catalytic converter, and the exhaust manifolds. More details on how to do this are below:

Top methods for flushing an exhaust system

Before we dive into the cleaning process, you might be wondering how the exhaust gets dirty in the first place. Well, there are two main culprits for this: harmful gasses and rust

By now, you already know the primary role of the exhaust is to collect and expel toxic fumes; hence, enabling the engine to work optimally. But during this expulsion, tiny amounts of these gases remain in the pipe forming a black coating. 

In addition to looking hideous, the soot buildup interferes with the performance of the car’s exhaust system. Specifically, it creates congestion, making it difficult for the fumes to be expelled. 

The fumes that build up on the surface of the tailpipes are one of the core reasons for cleaning this system. 

One other reason for flushing the exhaust system is to get rid of rust. But how does rust even form in this system? Well, there are three byproducts released from the combustion process that occurs in the engine: carbon dioxide, nitrogen, and water vapor. 

As these gases exit the combustion chamber, they get mixed with water molecules. As soon as the engine starts to cool off, the vapor condenses forming water. This is why you’ll sometimes notice water dripping from the tailpipe.

This phenomenon is not unusual; hence, it shouldn’t alarm you. 

The problem comes in when you only drive for short distances. When you do, the moisture lingers in the exhaust system, leading to rust formation. 

Whether your car’s exhaust pipe has dirt, dust, or rust, here’s how you should go about cleaning it: 

Materials you’ll need

How to flush the exhaust system

The exhaust system is made up of multiple components. So the best way to clean it is to divide the process into smaller tasks.

I like to start by cleaning the exhaust pipes and the exterior, followed by the catalytic converter and finally the exhaust manifold. Here’s how:

1. Cleaning the exhaust pipes with soap and water

Using good old-fashioned soap and water is the easiest way to revive a rusted or dirty exhaust pipe. Dip a clean cloth in the soap and water solution, then use it to clean the exhaust tip.

Cleaning the exhaust’s interior will require a more aggressive approach like a hard-bristled brush. Insert the brush as deep into the pipe as you can and remove the grime and rust.  


Once you’re done cleaning, the next step is to apply a degreaser. This is the best thing to use when you want to break up carbon deposits or rust residue. For the best outcome, you’ll want to apply the degreaser both on the inside and outside; preferably using a dry cloth

Once you apply, let it sit on the surface for a while. The degreaser’s package should have instructions on exactly how long you should leave it to sit.

Once that duration elapses, use steel wool to scrub it off. You’ll want to use circular motions for this process to remove all the degreasers.

Using  metal polish

If neither of the first two solutions work, another way to clean the exhaust system is by using polish. Start by wiping down the interior and exterior surfaces of the exhaust tip with a microfiber cloth. This is to remove any dirt or moisture present. 

Next, apply the metal polish using steel wool. Leave it to sit on the exhaust for a couple of minutes (or as recommended), before wiping it off with a different microfiber cloth. 

2. Cleaning the catalytic converter

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Have you done an emissions test recently? Did the exhaust system fail to meet the required standards? If so, the catalytic converter is likely to blame. 

Just in case you’re new to this, the catalytic converter is responsible for removing harmful elements from the exhaust gases. In particular, it oxidizes hydrocarbons and carbon monoxide. This makes them a little bit less toxic before they’re released into the atmosphere. 

Cleaning the exhaust tailpipes is a pretty straightforward process. However, cleaning the catalytic converter is not.

In fact, there’s a high risk of damaging the internal catalyst. This is why experts recommend taking your vehicle to a mechanic for this process. 

But, if you feel confident or have in-depth knowledge of catalytic converters, then go ahead and inspect it. You’ll need to buy an OBD-II scanner if you don’t have one. 

Next, plug this device into the OBD-II plug. Consult the car owner’s manual if you don’t know where this port is. 

Finally, turn the car key – without switching on the ignition – then key in your car’s model, make, and VIN number into the scanner. If there’s a problem with the catalytic converter, a specific code will pop up on the OBD-II reader. 

Once you’re done examining this part, the next step is to clean it. Look for a catalytic converter cleaner that works for your car. Then, wait until the fuel tank has about 4 gallons of gasoline. 

Add the cleaner to the fuel tank as per the instructions given before filling it up with gas as you typically would.

All that’s left now is to drive your car to the verge of running out of gas. You will know the catalytic converter cleaner worked if the check engine light doesn’t return. 

3. Cleaning the manifold

The manifold is another important component of the car exhaust system. It’s tasked with collecting all the exhaust fumes from individual engine cylinders and directing them to the catalytic converter

Gradually, this part can fill up with carbon buildup, grease, dirt, and more. And when this happens, it stops functioning properly- a factor that affects your car’s overall performance. The good thing is that regularly cleaning the manifold can prevent such issues. 

Before you start cleaning, allow the engine to cool down for at least half an hour. Next, detach the hoses holding the manifold and spray WD40 on the bolts securing the manifold heat shield. After spraying, remove these bolts so you can then remove the entire manifold. 

Soak the inside of the manifold in a lacquer thinner.

You’ll also want to scour the outside using a wire brush and steel wool. Then, apply the thinner on the entire surface and leave it to sit for a while. Once the manifold is clean, all you have to do is reassemble it. 

Can you put water in your exhaust pipe to clean it?

Yes, you can. However, it’s advisable to wipe the exhaust pipe afterward with a dry cloth. This is because allowing water to sit in the exhaust pipes for an extended period can cause rust.  

Measures to keep the car’s exhaust system clean?

Want to keep your car’s exhaust system in pristine condition? Follow these tips:

  • Simple water wash – if the exhaust system is covered in dirt, then simply wash it with a solution of soap and water. After washing, rinse it with clean water then wipe with a dry cloth to discourage rusting. 
  • Apply polish – applying metal polish is a nice way to prevent carbon build-up. It acts as a protective layer; hence extending the life of the exhaust.
  • Make regular visits to your mechanic – the measures above are essential for the proper maintenance of a car exhaust system. Still, you should consider getting professional services every once in a while. An expert can notify you of any impending problems and fix them before they escalate.


Would you like to flush the exhaust system but don’t know how to go about it? Turns out that his process isn’t as complicated as it sounds. All you have to do is break it down into small steps. 

Start by cleaning the exhaust pipe; both the interior and exterior.

Next, examine the catalytic converter using an OBD-II scanner and clean it if there’s a need to. Finally, clean the exhaust manifold and you’re good to go!


Dean Alvarez, TireForge Head Author

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