I have an exhaust leak on my '97 F-150 4x4 4.6L Seems to be coming from the left manifold to headpipe connection. It only does it when it's cold and seems to stop after the engine is warm (5-10 min). I'm assuming it will only get worse with time, so when I do go to fix it, is there a donut gasket beween the manifold and pipe, or is that sealed some other way.

 

It should just have a flare type connection. The pipe is spread out to fit around the rounded manifold. There should be no gasket there.
I would closely look to see if you have any broken manifold studs in the head. This seems to be a common problem with these engines. It will cause an exhaust leak in the same area.
Jimmy

 

Thanks lxman, I'll check the studs. Will spraying soapy water in the suspect areas work or is there a better trick?

 

Look for any black soot around the manifold and pipe.
Go to AutoZone or somewhere like that and get a cheap mechanics stethascope.
Jimmy

 

I haven't seen any soot. It may take a while to show up since it only does it when it's cold. Is the EGR tube prone to leaking? Does the EGR open after the engine is warm? I'm thinking that if it opens once the engine is warm, it releaves the backpressure that is causing the leak. Just an idea.

 

It only opens at part throttle when warm. It is closed when idling.