does it in neutral or in any gear

EDIT: noise is coming from the transmission

 

I have an idea. How about you stick your head under the hood and try to track this noise down and stop looking at a tach?

That noise could be anything. From your video it sounds like a vacuum leak.

 

you're probably right about the vacuum leak. one of the valve cover bolts are broken and the bolt is just sitting in its hole (not tightened and not sealed)

but the noise sounds horrible, or is that just what the valve train sounds like? why does it come and go at 3k rpm only?

 

Not gonna answer any more questions until you look under the hood.
Also wondering why we haven't bothered to fix known deficiencies?

 

Loose heat shield maybe, List what mods are done to the car and especially if anything was done right before this started.

 

just went out and looked at it, definitely coming from the transmission

the bolt is broken off in the cylinder head, that's why

heat shield is already off

no mods and ive been hearing this for quite some time now while normal driving. when you drive down a road that has things on the sides that echo sounds you hear it more (under a bridge, bridge with concrete walls, etc)

 

So that means you don't fix it?
https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/noise-3k-rpm-only-when-car-driving-2918535/

 

i don't have the tools to drill it out readily available. i will eventually

thank you for that thread. makes sense since december of 2011 i was being stupid drifting in the snow in a parking lot. lost control and rammed right front wheel sideways into a curb