What the f&ck is that sound? (video included)

[JEL]

I've been having this sound for a while now and I finally remembered to video record it and post it. I can't figure out what it is, and it always happens at 2,000 rpm under throttle, hot or cold. I've looked all over and simply can't figure it out, but it drives me nuts, it's a quick "tapping/buzzing" sound. At first I thought it was a skid plate, but it's not, nor is is suspension noise as I just rebuilt the entire suspension/steering system (drives great though). Any ideas?


It's a 2000 4x4 v6 with about 160k on the dial.
Thanks

 

[hambob]

Sounds like a computer I had in 1993. Is it possibly coming from in the cab? In the video its hard to tell.

 

[JEL]

Hard to tell in person as well, it sounds like it's either right under the dash or from the area before/after the firewall, but it's strange nature makes it difficult to pinpoint.

 

[Doc2012]

Check your exhaust. Could be a leak somewhere.

 

[Skidmarcx]

That does sound tough to locate... dumb question, but have you tried lightly tapping in areas up front you might hear a slight rattle?

 

[Swimmerboy2112]

Check your exhaust. Could be a leak somewhere.

Yep that's what I was thinking.

 

[TheeMikeB]

does it change pitch with RPMs?

 

[JEL]

Thanks for the replies. I thought exhaust as well but I (nor can my mechanic) find where in the exhaust it may be leaking. I did try knocking around where it's coming from but no luck, at first I thought it was my bad climate control blend servo, but after installing a new one it's still noisy. No real change in pitch with RPM, and it only happens in that limited range.

 

[0xfded]

Can't tell from the video, but from your description, it's the same sound mine makes right in that same range.

Based on some trial and error experimenting, I think it's the exhaust heat shields. My guess is that they vibrate in resonance with the transmission, since the sound doesn't happen when standing still. Pulling one off for a test changed the sound, and at some point I'm going to figure out how to deaden both of them and see if that does the trick.