Murphy finally got to my car! :grumpy: I own a 1992 Honda Accord DX (160K mi on it) that's been running fine until a couple days ago. 1. Now, when I start the car, for about the first half a second or less - as the engine comes to life - there's a rattling sound that I hear from the rear of the car. I'm fairly certain it's coming from the muffler or its vicinity. 2. During regular driving, this rattle is not heard again, unless I'm driving very slowly (<15mph) over a bumpy stretch, or if I do a not-so-smooth gear change at low gears. Makes me think something not too light (something bigger than a washer, small nut/bolt or chunk of rust) is loose in the muffler. 3. Another sound I hear is a low amplitude, medium pitch hum, or rumble, coming from about the same location that lasts for about a second or two in the lower gears (1 & 2). I do not hear it beyond about about 1500RPM (which is pretty low for a Honda). I do not hear this sound at all if my windows are up, or if I have the radio playing (so it's not terribly loud...but then, it's a Honda - the engine itself is as loud as a grumpy lion). 4. I think both sounds started appearing simultaneously, and neither is audible from the 3rd gear and up - not even when I floor the pedal on 4th or 5th (but the humming sound may just be getting drowned out by ambients). 5. Now, from a cursory inspection of of the muffler, I have the following to report: i) The muffler is fairly rusted near all the weld joints on the inlet side. ii) Shaking the muffler horizontally (by hand, so amplitudes were small - much less than an inch), made sound like there was a lot of loose rust chips on the inside. It was perhaps a rustling kind of sound. No clanging or rattling - but then, I didn't really thwack it up or down. iii) The back plate of the muffler (I'll attach a crude diagram, if I can) had an outward bulge in the small portion just below the outlet pipe. 6. That last observation suggests to me that there may have been an engine backfire or some similar weirdness that caused this. However, if the engine did backfire, I didn't hear it. On the other hand, I don't think I've ever heard an engine backfiring in real life, so I'm not exactly sure what it would sound like. But the engine backfire theory is a little weak due to the observation in point #4 - or so I think. So, what do you experts think may be the trouble? Any ideas or suggestions or questions? Should I go do an engine diagnostic? I don't have either the expertise nor the time to do anything more than rudimentary stuff myself, but I'd like to have an idea of the possibilities before taking the car to a mechanic. HELP!!!