Calling Guru's: Vibration rattle? Specific RPM range under acceleration.

[robb1887]

Alright Guru's,

I've had my truck (97 limited 3.4 4x4) for a while now... and its finally starting to drive me mad.

I have a weird "rattle" vibration-ish noise coming from the engine bay when under acceleration. From what I can tell its coming from the driver side, and only happens from ~2100-2500 RPM.

I've looked at the exhaust manifold "shield" and it looks like everything is tight, it sounds like a heat shield vibration from others I've heard. I thought it might have been my radiator fan lower shroud since I had lost a clip when replacing the radiator and thought the fan might be contacting it when spinning hard and pulling air, but I finally replaced that. It happens no matter the conditions, hot, cold, dry, wet, windy, rainy, snowy, on-road, off-road, engine cold, engine warm, low speed, highway speed, and everything in between.

I'm going to be doing a VCG job this Friday and was looking for advice of things to check while I'm in there.

TL;DR
Weird vibration rattle from 2100-2500 RPM, in any conditions, under acceleration. What to check?

Thanks for the help

 

[iowajosh]

I have a 4cyl but I have noticed my noises like that are the exhaust rattling around.

 

[robb1887]

Bump for any more ideas

 

[hambob]

Cat "shield"? sound can be deceiving.

 

[masphx]

I love these threads. Ever since I bought my Runner 20K ago it has had this sound. Check out this video. Does it sound like this...

1998 4runner sound - YouTube

 

[robb1887]

Update:
[MENTION=71420]masphx[/MENTION] from what I could hear it sounds like yours might be the "heat shield" from the cross over exhaust pipe.

I found mine was missing bolts between the exhaust manifold and the cross over pipe which allowed it to vibrate. Replaced the nuts/studs that were missing and its significantly quieter.

 

[robb1887]

Update:
[MENTION=71420]masphx[/MENTION] from what I could hear it sounds like yours might be the "heat shield" from the cross over exhaust pipe.

I found mine was missing bolts between the exhaust manifold and the cross over pipe which allowed it to vibrate. Replaced the nuts/studs that were missing and its significantly quieter.