Q: What Causes Cracks and Leaks on the Exhaust Manifold?

The exhaust manifold is designed to route exhaust gases away from the engine and into the rest of the exhaust system. A cracked exhaust manifold not only results in noise, but can also cause engine performance problems. This is because the oxygen sensors pick up the unmetered air entering through the crack and read it as a false lean condition.

Exhaust manifolds crack for a couple of reasons. For one, exhaust manifolds often crack due to the normal expansion and contraction that occurs as the engine is put through it’s normal range of operating temperatures. A cracked manifold can also be the result of a design flaw. Many modern manifolds have thinner castings designed to reduce weight. This makes them more susceptible to cracking.