Best Exhaust Sealant In 2021 (Review And Buying Guide)

November 26, 2021

Having an exhaust leak on your car is probably one of the most annoying things out of all car problems that exist out there. To start things off, the most annoying thing about an exhaust leak is gas getting inside the cabin. At first glance, you would want to diagnose this issue using an OBD reader but that won’t really help because it cannot point to an exhaust leak after the oxygen sensor location and exhaust leaks can happen anywhere. Today we will share with you the best method to find an exhaust leak as well as the best exhaust sealant to buy.

Before we get into that let’s learn about diagnosing an exhaust leak on your car using common tools.

How to find an exhaust leak on your car?

The exhaust is basically what runs from your engine to your pipe and sends the smoke out to the atmosphere after the fuel-air mix has been burned inside the engines. This whole system is built up by the exhaust head, catalytic converters, or particulate filters. These are all parts used by automakers to make the smoke released from cars as little harmful to the environment as possible.

Now that you know that the exhaust system is made up of these components you must also keep in mind that these parts are interconnected together by tubes clamped by flanges. The area where the flanges meet the tubes is most commonly known to have exhaust leaks, yes that tiny spot will cause that P0420 error code you are looking up.

To find exactly where an exhaust leak is blowing you can use a blower (hairdryer worked great for me) to push air inside your exhaust system. Don’t worry if your car has 2 exhaust pipes you can seal off the second pipe by using a glove or an old cloth. Once you are blowing air inside the exhaust system, start to soak the headers first with a mixture of water and shampoo, anything that can make bubbles works great.

If there is an exhaust leak then you should be seeing bubbles otherwise the shampoo and water mix will just soak a piece of metal. Do that for your whole exhaust system and make sure to go through this process carefully and not miss any spot. Once you are done you can use a marker to point the leak you want to seal. Now the interesting part, sealing the leak.

Best Exhaust Sealant In 2021 Editiorial Choice

Best Overall: J-B Weld

best exhaust sealant

J-B Weld is the best exhaust leak sealant that comes in the form of an applicable adhesive. This is the classic and most easy-to-use exhaust sealant because it’s liquid and you can shape it around the leak easily. The J-B Weld is an RTV (Room Temperature Vulcanized) meaning that it could withstand high temperatures.

Using the J-B Weld is very easy as the sealant can be pushed out with little force over your marked area. Let it cure for 1 hour according to the manual but you can also perform a test yourself. Our best advice with adhesive exhaust sealants is not to start the car after applying your favorite sealant of choice. This is because you will blow up all the soft adhesive you just applied over the leaking area. Using the J-B Weld as your exhaust sealant you should be expecting a red color after the adhesive is cured. Then it should be ready to go.

Tip: Don’t hesitate to put a little extra, if you dip anywhere else other than exhaust you can wipe it off while it’s still soft and not cured yet.

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Best Exhaust Gasket Sealant: Copper-Spray

One other place that is very common to get an exhaust leak is the exhaust gasket. This is the gasket placed between the engine block and the exhaust head and as miles roll it starts to bust. Never attempt to apply Copper Spray over the exhaust head thinking that you will seal the leak. This requires you to take off the exhaust head, install a new gasket (or use the same but gaskets are inexpensive generally), and coat it using Copper-Spray, it is the best exhaust gasket sealant out there and the application process is fairly simple. Make sure to use gloves if applying this spray can exhaust and coat the gasket with sealer both ways.

As one of the best exhaust gasket sealants on the market Copper-Spray itself helps to dissipate heat, prevents gasket burnout, and improves heat transfer. It fills minor surface irregularities, hot spots, and surface imperfections. Suggested applications include cylinder head gaskets, carburetor gaskets, exhaust manifold gaskets, and other high-temperature applications.

Tip: When finished spraying, flip the exhaust seal upside down and press to release all the remaining liquid from the pipe so you can easily use it next time without clocking the pipe.  Don’t ask yourself what is the best exhaust sealant because there is only one the rest will make you spend your money and solve nothing.

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Best Heat Wrap Exhaust Sealant: Design Engineering Exhaust Heat Wrap

Another good way of sealing an exhaust leak is using the best exhaust heat wrap. This is basically a material that will wrap around the leaking area and isolate any leaks. It is commonly used by tuners to wrap the exhaust headers before installation as it absorbs heat very well.

Some of the benefits of using the best exhaust heat wraps are low-cost sealing, prevention of corrosion or rust, and a better-looking exhaust head. Design Engineering seals the leaks at high temperatures, up to 1800 Fahrenheit. The sealing process is fairly simple, to cover small areas of leaking you won’t need as much heat wrap but make sure to cover 2-3 inches more from the leaking area to assure 100% sealing. Installing the heat wrap is pretty obvious, the sticky side will attach to the exhaust.

Tip: Make sure you find the leak and let the exhaust cool down a bit before applying the exhaust heat wrap. This is also the best exhaust sealant that comes in the form of a wrap but it will require some help to cover small areas, make sure to add additional stainless steel zip ties to your amazon order, it is already suggested and comes as a combo on Amazon.

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Best Exhaust Sealant Tape: 3M High Temperature Flue Tape

This is for real the easiest way on earth to seal an exhaust leak, just tape it. Before you do that you might consider going the extra mile and devote some time into making a better job at sealing the leak from your exhaust. The 3M high-temperature flue tape sticks to most metal surfaces and withstands temperatures of up to 600 degrees Fahrenheit. With that in mind, there is one single process to do before wrapping with the tape and that is cleaning and preparation.

Make sure to have a very clean area and it’s thoroughly dry before applying the tape because it will stick better and prevent rust or moisture from building up. It is the perfect and most convenient solution when it comes to emergency exhaust sealing. It can be used on mufflers too but it’s ideal for wrapping around and forming a unibody rather than a tape over a leak.

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Commonly Asked Questions

Q.What Is The Best Exhaust Sealant?

A: There is no final answer when it comes to choosing the best exhaust sealant. There are different types of leaking in the exhaust which can use different types of products to seal the leak. After all, all products will do the same job but it’s a matter of what your exact problem is and how you can fix it the easiest and most efficient way.

Q. What is the best exhaust manifold sealant?

A: There is only one product which we suggest using as the best exhaust manifold sealant. That is Copper Spray. The process of sealing an exhaust manifold leak is not the simplest and requires some nuts and bolts to be taken out but if you are reading this you know a thing or two about cars.

Q. What Is The Easiest Way To Seal An Exhaust?

A: You could also turn around into an exhaust leak flange. It’s basically a flange that will wrap around the leaking exhaust area and you screw it tight to keep it steady and ready.

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