Exhaust Manifold Leaks – Causes, Failure Signs, Potential Damage

Exhaust Manifold Leaks - Causes, Failure Signs, Potential Damage
Exhaust Manifold Leaks - Causes, Failure Signs, Potential Damage

So, exhaust manifold leaks, can be dangerous. And, also cause other costly problems.

The function of the exhaust manifold, is to collect the exhaust from each cylinder. And, then combine it, into one pipe.

It is bolted, directly to the cylinder head. Therefore, it is the first line of defense, from hot and dangerous gases. Consequently, once these gases exit the exhaust system, the exhaust manifold has done its job.

Above all, if there is a crack or any exhaust manifold leaks, the whole exhaust system is affected.

When gases come out of the engine, they are extremely hot. But, they do cool slowly, as they reach the tailpipe at the back of the vehicle.

Visual Crack On Exhaust Manifold
Visual Crack On Exhaust Manifold

So, if you smell exhaust from the engine compartment and hear a ticking noise, you could have a leak. Over time, the gases leaking from a manifold, will damage other parts.

If you think you have a leak, always start with a visual inspection. Look for black soot around the manifold and downpipe connection.

Exhaust Manifold Leaks, Will Produce A Few, Failure Signs:

  • Excessive, engine noise
  • Decrease in power, acceleration, and fuel efficiency
  • Burning smell, coming from the engine bay

Exhaust Manifold Leaks, Can Be Caused By:

  • A cracked manifold
  • Leaking gaskets
  • Loose or broken bolts or studs

Cracked, Exhaust Manifolds

So, leaks in a manifold are often, cracks in the metal. And, are due to the intense temperatures of the engine. Cracks may start out small, like a hairline crack. And, may be apparent, when the vehicle is first started. Once the manifold heats up quickly, the crack might self-seal, as the metal of the manifold expands. Actually, this can also, affect an intake manifold.

Visual Crack On Exhaust Manifold
Visual Crack On Exhaust Manifold

As a result, the noise coming from exhaust manifold leaks, then becomes less apparent. However, over time, the hairline crack will begin to increase in size, due to constant heating and cooling.

Leaking, Manifold Gaskets

The gasket is another area of concern. Because, it has to sustain the expanding and contracting, of the heated metal. Its failure signs, are similar to the cracked manifold and could, become a larger problem.

Exhaust Manifold Gasket Leaking
Exhaust Manifold Gasket Leaking

Exhaust manifold gaskets, are very important. Because, they are the main gasket, that seals the entire exhaust system. So, if the exhaust manifold gasket fails, it can cause problems, with the performance and drivability of the vehicle.

Loose Or Broken, Bolts Or Studs

Sometimes an exhaust manifold starts to leak, because a bolt or stud has broken. Exhaust manifold bolts and studs, both suffer the same fate. Consequently, getting brittle from too many, heating and cooling cycles. Finally, with expansion and contraction of the whole system, something has to give. As a result, causing exhaust manifold leaks.

Broken Bolts In Cylinder Head
Broken Exhaust Manifold Bolts In Cylinder Head

Consequently, making broken bolts or studs, a fairly common problem. Not to mention, the repair for this, can be a nightmare as well. The good news today is, there are better tools and techniques, for making this repair easier.

Potential Damage, Caused By Leaks Include:

  • Burned, exhaust valves.
  • Improper fuel trim  (as the leak introduces extra oxygen that is picked up by the (O2) oxygen sensor.)
  • Slow warm-up time  (which also causes, using more fuel.)
  • Catalytic converter fails too soon.
  • Sensors ((O2) oxygen sensors).
  • (EGR) Valve function.

So, these factors all depend on, where the leak is located, in the exhaust system. The further away from the engine and the catalytic converter, the less damage can happen.

Leaking Gasket
Leaking Exhaust Manifold Gasket


So, if you have any exhaust manifold leaks, it will have an impact on, the pressure in the exhaust system. As a result,  loosing fuel economy and leading to, higher emissions.

Thank You !