Cracked Exhaust Manifold A cracked or broken exhaust manifold is most often caused by one of two things. The first reason is heat cycles and/or age. Over time, the manifolds just can’t take the heat anymore (literally and figuratively), and cracks begin to form in them.Click to see full answer. Correspondingly, what causes a cracked intake manifold? Why manifolds crack and leak As the fatigue becomes worse, it’s possible for the manifold to develop cracks. Like the manifold itself, the gasket is subjected to significant heat, as well as expansion and contraction. It will eventually fail (this is normal, and cause by nothing more than general wear and tear). will cracked exhaust manifold damage engine? This can damage plastic components in the engine bay. There’s also the possibility that it will affect engine performance. If your exhaust manifold is cracked or leaking, the back pressure in the exhaust system will be incorrect, which can reduce engine power, cause sputtering and other problems. Similarly one may ask, what happens if your manifold is cracked? Exhaust Manifold If the manifold is cracked or has a leak, the back pressure in the exhaust system will be incorrect, which reduces engine power. These leaks permit hot toxic gases to escape, which can damage other components in the engine compartment. A leaking exhaust manifold can also affect engine performance.Can you fix a cracked manifold?If the crack in the manifold is narrow, as opposed to a large enough that you can get a finger inside it, it may be possible to solder it; these repairs can only be undertaken if the crack in the exhaust manifold is not too large.