Popping sound, it's continuous...

[Casey B]

This is the best was that I can explain it. Do you ever hear a popping sound coming from under the Trac, or any vehicle for that matter, after you have parked and it is cooling off? That sound has become continuous in my Trac. It doesn't matter if I'm idling cold, driving (accel and decel), or idling hot. It's a pop that happens every so often. Almost predictable and it didn't start until my last dealer visit where they upgraded the power steering pump, replaced the a/c compressor, and packed the front bearings. It's annoying and I know it wasn't there before. Any ideas as to what this may be? I've tried isolating the sound by crawling under the Trac but can't figure out where it is coming from.

 

[EddieS'04]

Catylatic converters cooling down. My '04 does it. Other cars I have had done it too...

 

[Casey B]

After reading more about cat converters, I think it's a possibility. My mpg's have went down over the last couple of months. It sounds like someone is throwing a rock and it is hitting the underside.