i just picked up a very nice 90 F150, Lariat 4WD with only 119,000 miles on the 302. It has a exhaust leak on the passenger side that you hear slightly louder when it is cold and it quiets down somewhat when warm. expansion and contraction I know.......but how do I determine exactly where this leak is and is there a particular troublesome area to look for......thanks

 

I think the best way it just to grab a flashlight and look and listen while the truck idles. I do know that the stock exhaust manifolds on these trucks are notorious for cracking or warping away from the block, might want to start there and work your way back.

-Chris

 

I'd bet it's either a cracked manifold, or a hole where the y-pipe joins. My '87 had a manifold that had cracked completely in half, right between two exhaust ports, as well as a bunch of rust holes in the y-pipe. Not anymore though She sounds good with a 2.5" mandrel bent Y-Pipe, and a 3" single exhaust.

 

I recently bought a 96 with a 5.0 and it had a exaust leak on the passenger side. Took a look, listened and felt around, found it at the exhaust manifold. It is cracked almost all the way around. It must be common problem for right side because is it more difficult to find one for that side.

 

If that engine has it, check the small tubing goes back to recycle exhaust. Those break/crack with some frequency and can sound that way.

 

He's talking about the EGR tube. And yes, those can be prone to rot out too.

-Chris

 

I just had a mechanic look at mine yesterday and he told me that it was coming from the y pipe where it meets the manifold. He had a stethascope I think ( the tool that doctors listen to your heart with) that he had put a hose on and took the disk off the end. He stuck it up there while the truck was running and listened around. He also said that at his shop they just get the manifolds milled and do not use gaskets when they work on them because of heat transfer causes them to blow out.