I have developed a strange noise... almost a rattle.. from what I believe is the under/passenger side of my 99 TJ. It doesn't happen all the time, seems to happen mostly when it is warm and has been under a load (i.e. stop-n-go traffic, highway driving, etc) for a while. The rattle is the loudest when under load, i.e. when I take off from a stop sign or accelerate up a hill. It has gotten louder lately. One day it was so bad, the "rattle" (sounds like metal tapping metal, actually) was happening at idle. I got out, and since I was in uniform and couldn't crawl under it, I just stuck my foot on the tailpipe to see if that would stop it, and it seemed to.
I'm finally home, but can't get it to duplicate at a time when I can put it up on stands and take a look at it. Every time I do, it won't duplicate. I DID find a lot of green/white powdery stuff caked on the pipe between the cat and the muffler. I've never seen that before. The pipe has a thick coating of this junk from end to end of the pipe connecting the cat to the muffler.
Any thoughts on this? It isn't one of those "it's a Jeep, it makes noise, deal with it" situations. My wife thought the muffler was dragging yesterday it got so bad.
By the way, I tapped, pulled, pushed, and prodded the exhaust from the downpipe back. Nothing loose that I could see.
Eric
99 TJ SE