I have a 2003 Surburban LT, 2-whl drive. Recently at low speeds (25 mph and less) I get a rattling noise, which seems to come from underneath the passenger seat. Also, when its off, I get a cooldown popping noise. Anyone have ideas to problem (if any) and fix repair price? Thanks [&:]

 

Our 2000 does the same. I've heard others do it also, so I've never worried about it. We have had it going on 5 years now with no problems from this.

 

Heard that noise before on an old Dodge Omni. It was driving me crazy. Finally jacked her up and pounded on the muffler. Found the noise. It's the baffles have come loose in your older muffler or collapsed altogether. Any way you look at it you need a new muffler. Since then, have often noticed that sound on parking lots when old ****boxes drive by. Don't know about the other sound though.

 

Just take it to a muffler shop and have them diagnose it.

 

Usually the heat shield on TOP of the muffler or converter has partially rusted off.
I bought4 large radiator hose clamp at parts store (connect all 4 together to make a large one) and wrap it around the muffler and shield. Problem solved.