Hillsborough County schools get out May 25 for the summer break. ChaCha on! 7 years ago
Â· just now. Report Abuse. A cast iron manifold will expand and contract, the JB Weld will not. I think JB Weld is fantastic stuff (have some as we speak) but not for a cracked exhaust manifold.You can always check out their website: http://jbweld.net/index.php I only have experienced JB with cast though, if your manifold is another material you may get lucky.ource(s): Q: Will J-B Weld work on an automotive exhaust? A: Because of the extreme temperatures of exhaust systems, we do not recommend J-B Weld for use on exhaust manifolds and catalytic converters.
The exhaust system itself has many parts, some are very complex. The manifold is simple in design and function. They connect to the cylinder head and funnel hot exhaust fumes into one simple exhaust pipe. An exhaust leak can be due to a blown exhaust gasket, which is a relatively inexpensive fix, if caught soon enough. Leaks can also come from cracks in the manifold itself.