My '89 Cherokee got an exhaust leak while under warranty, off to the dealer it goes. "It has a cracked exhaust manifold and it will be 6 weeks to get another." I go to the dealer to see the damage. The manifold was actually a set of short tube headers
. In amongst the bends, sure as life there was an obvious crack. "So you're going to give me a loaner car while you can't provide the parts?" "Oh no. We can't do that." "Give me that manifold!" I took it to work the next day, drilled the ends of the crack, cleaned it up real good and took the MIG welder to it. Took it back to the dealer that afternoon. The next afternoon they have it back together. "Do you think you could do that again? It seems to be a common occurrence with these 4.0s."
Nothing showed bad on x-ray. She tried blasting with air and pushing spots with super cold swab. Nothing. 
This thing has been ringing my bell for a couple weeks now. She saw one corner of a molar that might break off eventually, but I don't think the problem is that far back. So, I guess it's just wait till it gets worse...
