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.
Report to Moderator. So I've got a JD tractor with a fuel tank leak. It seems that there is a crack along the seam of the tank about halfway up. I had the tank out a few years ago and put some JB weld on but that hasnt seemed to seal things up.e: Diesel fuel tank repair in reply to DeltaRed, 01-01-2013 09:05:58. On diesel and oil tanks that need mending, use the exhaust from a vacuum cleaner and put the hose in the tank. This will keep the fumes and smoke blown out so they can't reach an ignition temp or mixture.