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How To Find Exhaust Leak On Semi Truck? (11 Helpful Tips!)

Are you driving in the middle of the road when you suddenly hear strange noises in your engine or smell like gas? Probably, there is a leak on your semi truck’s exhaust system.

The exhaust system of a semi-truck is one of the most important things drivers should always check since it plays a vital role in making the toxic gasses less harmful in the semi-truck.

Some people do not pay much attention to their semi truck’s exhaust leak, especially if it is unnoticeable. 

But do you still need to wait for your semi-truck to produce dangerous fumes or experience failed emissions before checking it? No, you should find the culprit right away and have it fixed.

Here’s a Quick Answer on How to Find an Exhaust Leak on a Semi Truck:

An exhaust leak on a semi truck can be found by visual inspection. Wait until the exhaust pipes cool down, then locate the exhaust manifold. Follow the pipelines under the truck and check the mufflers, catalytic converters, or resonators for possible holes, creases, or dents that cause leakage.

How do you know if your Semi-truck has an Exhaust Leak?

There are several signs and symptoms of a possible exhaust leak on your semi truck that you should not neglect.

Noises from the engine, loss in power and acceleration, lower fuel economy, and smell of gas are the common factors present when there is an exhaust leak on your semi truck.

The most common are noises you hear coming from the engine will be rumbling noises while driving or if you hear a hissing sound as soon as you start the engine.

If you do not notice it early, the exhaust gasses will also affect the performance of your semi truck’s engine. Frequent part failures and engine acceleration may happen.

You will also wonder why your semi truck’s air-to-fuel ratio seems slightly off, resulting in regular refueling stops more than usual.

But the most important thing you need to know about a possible exhaust leak is the strong smell of gas while driving.

If any of these happens to your semi-truck, consider having them checked. Prevention is better than having your semi truck undergo a significant repair.

Can you Smell or See an Exhaust Leak?

The most common way to find out about exhaust leaks is the smell of exhaust fumes in the cabin.

You can smell an exhaust leak due to unusual exhaust fumes or a gasoline-like smell that spreads inside the semi truck.

You may not see the exhaust leak, depending on the intensity of the air leakage.

But it is more likely for you to hear it since it is quite an unusual sound whenever you turn on the engine or hit the brakes when driving.

What does an Exhaust Leak Sound Like?

There are different sounds an exhaust leak in semi trucks produces. The sound of an exhaust leak depends on the possible location of the leakage.

For example, if you hear rattling sounds when you accelerate, the leak may come from the muffler or catalytic converter. If a hissing or tapping sound comes from the engine, it is more likely the manifold gasket is at fault. 

Will a Carbon Monoxide Detector Pick up the Exhaust leak?

Semi trucks also produce carbon monoxide, so it is normal to think if a carbon monoxide detector can detect an exhaust leak.

A carbon monoxide detector may only pick up inevitable exhaust leaks, especially if there is a high concentration of carbon monoxide in the exhaust gas.

An exhaust leak can even damage a carbon monoxide detector because it produces other components that may harm the device.

Will an Exhaust Leak Affect the Performance of your Semi Truck?

The main reason you need to get your semi truck’s exhaust leak fixed is that it continues to cause damage to the engine.

An exhaust leak affects the engine’s performance, resulting in losing power and poor acceleration. It may not run as smoothly or as fast as it was before.

It is dangerous for you to drive a semi truck with an issue with the exhaust pipes, so it will need immediate attention to prevent more severe problems.

Can an Exhaust Leak Cause a Check Engine Light?

An exhaust leak may often trigger a check engine light due to a frequent and sudden decrease in air-to-fuel ratio or fuel efficiency.

The leak will cause the oxygen sensors to throw off their readings.

Will an Exhaust Leak Throw a Code?

This scenario is on a case-to-case basis. The exhaust leak can throw a code depending on how significant or severe the intensity of the leakage is for it to affect the oxygen levels.

The location of the leakage will also determine the code it will throw.

Can you Drive with an Exhaust Leak?

Since there are instances when you cannot tell right away if your semi truck has an exhaust leak or not, you may still go for a drive and may not notice anything wrong yet.

Technically, you can still drive even with an exhaust leak. 

However, it is unsafe and illegal since you can face several issues or violations while hitting the road with a damaged exhaust.

An exhaust leak can cause severe damage to your semi truck if left unattended, making it more prone to danger. Thus, you need to have it checked or undergo immediate repairs.

How do you Find an Exhaust Leak with Soapy Water?

Once you know there is an exhaust leak on your semi truck, you may find it challenging to find the exact location of the affected exhaust pipe.

Soapy water helps you find that leak right away by showing you bubbling areas. Tiny bubbles indicate the source of the leakage.

Indeed, it is an effective way to find out the exhaust leak right away. It is also so easy to do.

All you need is to mix soap and water. There is no specific ratio to follow. As long as you think the mixture can produce more bubbles, it is good to go.

Look for a spray bottle, then add soapy water. Crawl under your semi truck and spray the soapy water on areas with a possible exhaust leak.

You will then start seeing bubbling areas of the pipes where you sprayed.

While you continue to spray the soap water on other locations, you may even see some parts that also have leaks. If this is the case, then you can fix them right away.

Checks on Semi Truck Exhaust you can do to Pick up a Leak.

There are several checks you can conduct to find out the exhaust leak of your semi truck.

You can start inspecting the exhaust system for potential failures with the typical signs or symptoms of a possible exhaust leak.

You can start checking under the semi truck and look for breaks or cracks on the welds, improper alignment of pipe connections, burned gaskets, leaks on clamp connections, and leakage on the flex pipe, where most failures in the exhaust system happen.

Aside from checking the visible issues on the system, you may also monitor unusual sounds or audible leaks whenever you run or turn off the engine.

The smell of exhaust gasses will also help you confirm exhaust leaks and how you can fix them.

How do you Fix an Exhaust Leak?

Fixing an exhaust leak helps you maintain the performance of your semi truck’s engine.

There are two ways you can fix an exhaust leak, depending on its location. The first one is from the manifold or the joints. The second is a leakage from a break or a hole in the exhaust system.

To fix an exhaust leak from the exhaust manifold or joints, you need to seal the leak by replacing the gasket.

The process is quite challenging or complicated, especially if the bolts in this area are too rusty.

For an exhaust leak coming from a break or a hole in the exhaust system, you need to replace the pipe part where there is a leak.

You can do it by disconnecting the joints and changing that part of the exhaust to a new pipe.

Since the process is quite expensive and challenging because of rusted bolts and some sections of the pipes.

You can bring the semi truck instead to a muffler repair shop to put in a new pipe and ensure there is no leakage in the exhaust system anymore.