Symptoms of Exhaust Leak – Causes + How to fix it

Unless you’re an enthusiastic gearhead, you probably don’t think about your car’s exhaust very often unless something goes wrong. An exhaust system is almost designed to go unnoticed, as it quietly and efficiently diverts exhaust gases from your engine and out of the car with a minimum of noise and vibration when working normally.

However, if your exhaust develops a fault, such as a block or a leak, it can seriously affect your car’s performance, fuel efficiency and more. Leaks are one of the most common faults with exhaust systems, so let’s look at how you can detect and fix a leak in your car’s exhaust system.

What are the symptoms of exhaust leaks?

A leaky exhaust system can cause serious mechanical issues and even harm the people inside your car if left untreated, so you need to know the symptoms of an exhaust leak to stay safe. Fortunately, a leaking exhaust tends to have several noticeable symptoms, such as:

• A loud noise: If you start your engine and hear an increasingly loud noise coming from your engine, it could be an exhaust manifold gasket leak.
• Vibrating gas pedal: A leaky exhaust will cause vibrations throughout the engine, so get it checked out if you notice your gas pedal vibrating.
• Poor fuel efficiency: Leaks in your exhaust system affect your engine efficiency, so a sudden drop in fuel efficiency could be due to a leaky exhaust.
• Unusual noise when accelerating: If you can hear air leaking or whistling when you accelerate, it’s a clear sign of a leaking exhaust.
• Unusual odours: Many exhaust gases have noticeable odours, so if your car starts to smell of engine fumes, you should quickly get your car checked out.

How can you tell if you have an exhaust leak?

In addition to all the signs, we listed above, exhaust leaks will often make themselves known by their smell, sound and vibrations, which can be noticed throughout the car in extreme cases. If you begin to smell exhaust fumes, feel unusual vibrations or hear hissing or rattling, then you may have a leak in your exhaust system, so you should have it checked out as a matter of urgency.

Another less obvious symptom of an exhaust leak is reduced fuel efficiency, which is often overlooked or blamed on some other factor, such as the age of your car. If you notice that your car is guzzling petrol or not performing as well as it used to, check your exhaust system for leaks.

What does a leaking exhaust sound like?

Exhaust leaks typically produce hissing or tapping sounds, especially during a cold start or when accelerating, as these tend to involve temperature changes or higher pressure in the exhaust. Tapping sounds are usually caused by broken pipes colliding, while smaller leaks make hissing noises as the exhaust gases escape.

How does an exhaust leak affect your car?

Leaks in your exhaust system impact the power, acceleration and fuel efficiency of your car, as they decrease backpressure and interfere with the normal combustion process of your engine. In severe cases, exhaust leaks can even harm the car’s occupants and cause damage to other engine components as they leak toxic gases and heat into the engine bay and car itself.

However, even minor engine leaks compromise the integrity of your exhaust system, as they allow corrosion and exhaust deposits to build up in your exhaust system.

Can you still drive with an exhaust leak?

While it is possible to drive with an exhaust leak (because they rarely disable cars), it is unsafe and will increase your risk of serious mechanical failure. Even minor exhaust leaks can quickly turn into serious issues, so you should try to get your car inspected and/or repaired as soon as you notice the warning signs of an exhaust leak.

How to Fix an Exhaust Leak

Depending on the size, type and location of your exhaust leak(s), you may be able to fix it yourself, without the need to take your car to a professional garage. If you want to try and fix a leaky exhaust yourself, you should:

• Gather your tools: You’ll need gloves, sandpaper, a wire brush, an exhaust band clamp and a muffler bandage with putty and detergent water.
• Locate the leak: Exhaust leaks can be tiny and incredibly hard to find, but if you can get under your car and turn the engine on, you should hopefully be able to see and/or hear the leak.
• Clean the area: Using your sandpaper, wire brush and water, try to clean any debris, grease or rust surrounding the exhaust leak.
• Seal the leak: If you’re looking at a small leak, you should be able to seal it with putty or epoxy resin and make sure to let it dry fully before driving again.
• For larger holes: Use exhaust tape to cover up larger holes, wrapping the tape around the whole exhaust pipe for a secure fit.
• If that doesn’t work: If you can’t fix your exhaust leak using widely available tools like putty or exhaust tape, then you’re better off taking it to a professional mechanic.

Note: Attempting to repair an exhaust leak yourself can be very risky – due to the heat and toxic gases released by your exhaust system – so be very careful and take all reasonable precautions.

The Bottom Line

Even a small fault in your car can cause big issues if left unchecked, so stay vigilant and make sure to get any issues or mechanical irregularities checked out as soon as you can.