J30 noise question.

[DJ MF]

I'm going to describe this the best I can. My initial suspicion is the catalytic converters...but someone with more knowledge can probably pinpoint it.

I'm getting a a 'rattle' after startup that sounds as though it's coming from the underside middle of the car. At idle, it's inaudible. On acceleration, it's fairly loud, but not overwhelming. After the engine warms up and reaches normal operating temperature, you can't hear it at all under daily driving, even with the throttle wide open.

BUT

You can hear it over 3000 rpm if you're driving next to a wall or something that will rebound the sound.

Like I said, I haven't gone underneath yet, but I figure it's the converters, especially considering where the sound is coming from.

Could it be something else?

MF

[scdanny]

Probably a loose exhaust heat shield. Check for this first.

[R4v3n]

Check this site

http://www.fuzzycats.com/j30_diy.htm

This guy registered on here, Carlos, made that site. It's extremely useful, and it has a section on muffler rattle.

[TxGuy67]

My J actually had rocks rolling around in it. It is a loose metal exhaust shroud. A quick spot weld will fix it.

[diamondj30]

both j30s i had did the same thing even with no shields anywere.really pissisn me off.even after complete exhaust system change.one day i bent the ncarrier bearingn shield and it went away but came back.definitally hot and cold sensitive.im sorry but j30s are very noisey for a luxo.othern models are far quiter.

[VimyJ]

You can spot weld the shields or even take them off. My J is silent.