I have an 89 Ford Superduty with a 460 engine. The engine was replaced with a Jasper last Sept. by a jasper insatller. When the engine was pulled they told me the drivers side exhaust manifold was cracked and replaced it. About 4000 miles later it cracked again. Exhaust leak. What would cause this? I know this is probably a pretty generic question but if someone needs more info ask. Thanks. Matt

 

well, either something's hangin out of a hanger toward the back, or a motormount's bad,because something's causing that manifold to flex in a way that it doesnt want to.