Horrible rattly grindy sound at 3-4k

[Gazmondo]

Wondering if someone can help me with this, I have a rattly/grinding noise coming from the engine bay at around 3-4k rpm, whether moving in gear or stationary in neutral. A fellow 200sx'er has said possible bottom end bearing. It doesn't sound tappy or knocking at all.

I've attached a video.

[Hugh Janus]

"vid not found"

[Gazmondo]

Ammended ��

[BreadBin]

Doesn't sound like bottom end to me, more like a heatshield.

[Gazmondo]

I'm yet to get it on the ramps, I had very high knock yesterday on high boost - 91. The clutch is also on its way out, gonna get it on the ramp tonight and have a good look underneath.

[shaboy]

not listened to the vid (at work) but it could be a gasket (if you have metal ones) or heat shield, the might only vibrate when the revs get to a certain level causing the right frequency.

[auz200sx]

If clutch Is on it way out lm going for realise bearing

[Gazmondo]

The clutch is on its way out, and the release bearing is also, as I can hear it when it's not engaged.

Didn't think the release bearing made that sorta noise though.

[turbodonkey]

I seem to have this problem to. Just as I start hitting 4k. Weird thing is it only happens in 3rd gear. Or so I've noticed anywag

[ANDY black s13]

Its hard to tell from the video sound track,but like others have mentioned it sounds like a heat shield or something similar
If its doing it stationary you could get someone to hold it at the rev point it makes the noise,and you go over the car chasing the noise
I suspect an exhaust heat shield, the rear most one above the rear silencer can rot around its bolt holes
or one of them is slightly loose or has been bent so its just touching something like the exhaust or the flour pan?

[Jon]

The video is better than a text description, but is still hard to tell what's going on.

If you still have the thin metal heatshield over a standard exhaust manifold, that would be my first place to check. The thin heatshield rusts around its fixing bolts and comes loose and then vibrates. Mine certainly did.

Next would be other similar thin heatshields, as said above, exhaust downpipe, catalyst, and further back.
As a means of diagnosing where the noise is coming from, simply bending one heatshield a bit should let you know which one is to blame, as the noise will change, after you bend the culprit.

EDIT: which is almost exactly what ^^^ ANDY black said