An exhaust manifold leak is a serious issue, as it means that spent combustion gases from your engine are directly escaping into the atmosphere. This isn't a desirable situation, and may deem your vehicle unroadworthy as well. That's why it's crucial to identify and repair such leaks at the earliest.

Not sure where to start when finding exhaust parts? Just check out our Performance Exhaust Systems section, and you'll find everything right there, from mufflers to manifolds, and even entire kits.

What Does an Exhaust Manifold Do?

The exhaust manifold collects the spent gasses after they have been combusted, and sends them down the exhaust pipe into the catalytic converter, where harmful gasses are somewhat neutralized. The exhaust manifold directly attaches to your engine block. If your engine is an inline, or straight type, there'll typically be a single exhaust manifold. If your engine is of the V-type or flat type, there'll be two exhaust manifolds.

Signs of an Exhaust Leak

How can you tell if you're having an exhaust leak, regardless of whether it's at the manifold or elsewhere in the system? Here are the five best indicators that you've got an exhaust leak.

Increased Noise

The most common symptom of an exhaust leak is increased engine noise. While some may think a leaky exhaust sounds cool, the fact remains that your vehicle is no longer road legal. You may also hear tapping or clicking noises if the leak is from the manifold.

Exhaust Odors in the Cabin

Can you smell exhaust gases in the cabin, even with the windows rolled up? This is a pretty common symptom of an exhaust leak. This is actually quite dangerous, as certain exhaust gases such as carbon monoxide are odorless. You could literally suffocate while driving and meet with an accident.

Poor Fuel Economy

An exhaust manifold leak in particular can result in reduced fuel economy. This is because modern engines with electronic fuel injection monitor several parameters, including oxygen content in exhaust gases. A leak in the exhaust can cause the readings to become incorrect, resulting in the engine control unit increasing fuel flow.

Poor Acceleration

Remember that your exhaust system needs to have some backpressure for your engine to perform at its best across all conditions. An exhaust leak minimizes that backpressure, and your vehicle's acceleration will noticeably suffer.

Check Engine Light Illuminates

On most modern cars, an exhaust manifold leak will trigger a Check Engine light (CEL). This can be the first indicator at times, but on older cars or those with less sophisticated engine management systems, the other symptoms described above may manifest before the CEL lights up.

How to Find the Leak

Finding the leak will usually require professional attention. Your car may be placed on a hoist with the engine running, and a technician will attempt to trace the leaky spot. Sometimes, the leak is broken studs, and you'll be able to see missing heads on those bolts. Large leaks may be visually noticeable with black carbon traces around the leak, but smaller leaks or gaps in the exhaust manifold where it meets the engine block will be harder to detect. That's why it's best to take your car to a workshop to diagnose an exhaust leak rather than try to do it yourself.

Options & Costs for Repairing Exhaust Leaks

Repairing an exhaust leak can take a myriad of forms. Typically, it can cost anything from $100 upwards to properly repair an exhaust leak. Trickier manifold leaks that require the engine to be disassembled in the vehicle and the manifold to be replaced with a new one can exceed $1,000 in repair and labor costs.

Other than the manifold, the exhaust piping, catalytic converter, and muffler can all develop leaks. Some minor leaks in the exhaust piping and muffler can be repaired by welding, but catalytic convertor leaks usually necessitate the replacement of the catalytic converter. The good thing is, these components take a very long time to deteriorate to a level sufficient to cause an exhaust leak. The most likely cause of an exhaust leak from an exhaust pipe, catalytic converter, or muffler being damaged due to an impact. Driving over a curb and striking these components, or a stone kicked up by your tires in the right manner are two possibilities.

Exhaust manifold leaks can happen due to thermal stresses, as well as worn-out gaskets and broken bolts. Your vehicle's engine goes through multiple thermal cycles each time you start it, run it, and allow it to cool down. Furthermore, your engine and related ancillaries are subjected to vibration, as well as movement as you accelerate and brake. Worn-out engine mounts can increase this range of motion, causing more damage as a result.

Can You Wait it Out?

It's not recommended to wait for too long before repairing an exhaust leak. Sure, you might be able to wait a week or two if it's a minor leak, but you shouldn't wait too long. Left unchecked, a small exhaust leak will simply become larger and larger, and what could have been repaired before may now require replacement of parts.

Don't forget the major risk of gases, including odorless carbon monoxide entering your vehicle's cabin and quietly poisoning you. If you start feeling dizzy, light-headed, or disoriented while driving, immediately find a safe place to pull over and exit your vehicle. Try to call a tow truck. If you must drive home, do it with the windows rolled down and the climate control system switched off.

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