Help me figure out this L36 engine noise.

[Bugsi]

https://dl.dropboxusercontent.com/u/370 ... .24.59.mp4

Noise starts out after the car warms up, after driving 15 to 20 minutes, or just letting the engine run while in Park.
It sounds like it's coming from everywhere, but here's what we've done to rule out various things:

-Belt has been replaced.
-Water pump has been replaced. (Twice, just for good measure.)
-Tensioner assembly has been replaced.
-Power steering pump has been replaced.
(Note: Those items were original and needed replacing, even though they were not the cause of the noise.)
-Harmonic Balancer has been replaced.
-Torque converter has been replaced.
-Trans pan dropped, filter & fluid changed, nothing unexpected in pan. Trans was rebuilt ~5 years ago.
-Oil pan dropped, lower end of the engine inspected. Nothing unusual. No metal in oil.

I thought it must be a spun bearing, so we dropped the oil pan and the bottom of the engine looked pristine, no metal fragments anywhere. Oil was clean. My mechanic obviously can't figure out what it is, so I'm turning to the experts here. Any ideas of what this could be, or what my next troubleshooting step should be to isolate this?

Finally, it does this WITH THE BELT OFF, so it's not the AC compressor or the alternator.

When it starts making this noise, it does it gradually, sounding something like a chicken clucking:
https://dl.dropboxusercontent.com/u/370 ... .16.04.mp4
(some guy asks me about his flat tire while I'm filming, and I have to tell him I don't work there.)

Other than this noise, the engine runs perfectly, and the transmission shifts perfectly. This is super frustrating and I've spent a truckload of money on it without finding the actual cause.

[RJolly87]

You sure an egg didn't pop out of the tail pipe just after that last vid?

[RJolly87]

Have you dropped the tranny pan to see if there is any fragments there?

Does the engine bog at all when it makes the noise? I am also wondering if it could be the transmission pump.

[Bugsi]

Have you dropped the tranny pan to see if there is any fragments there?

Does the engine bog at all when it makes the noise? I am also wondering if it could be the transmission pump.

Yes, we dropped the trans pan and replaced filter and changed the fluid. No unexpected fragments were found in it, and the trans had a rebuild roughly around 5 years ago. Would I be correct that the transmission pump is *inside* the transmission?
(I'll add that the trans fluid & filter were changed.)

And no, there's no engine bogging. Revving the engine if anything makes the noise very temporarily go away, and it comes back as the engine comes down to idle. The noise doesn't really change pitch at all either, even if you rev the engine a bit.

[RJolly87]

Yes, I believe the transmission pump connects to the torque converter, but I don't know exactly where it is.

I have never heard a noise like this however.

I have heard of some funny noises however when the PCV valve is not sealed properly, and the noises go away when the oil cap is removed. I would also be curious if an induced vacuum leak would have any affect on the noise. I am curious if it could be something resonating with airflow, but most of the things I can think of should stop when the throttle is cracked open.

[Bugsi]

Got it warmed up and began to squeal. I pulled the oil cap off. There was a decent vaccum, a big SUCK in of air when I pulled off the cap and the engine immediately died. This means. . . What?

[Bugsi]

Would it be surprising to find that there was NO PCV valve in the engine at all? There was none in it. It has one now. Retesting.
*EDIT* I let it run and run and it just wouldn't squeal any more. I suspect not having a PCV valve is a bad thing. I'm hoping that's all it was. (Cost $3.27.)

[RJolly87]

You can't be serious...

[Bugsi]

You can't be serious...

Totally serious!

[RJolly87]

I truly hope it's fixed at least, if anything to end the madness, but if that's all it was, I'm truly sorry :(

Not sure if I should hope it's fixed just to end the madness, or hope it's still broken, just to keep taking cracks at it only to find out it is a horrific and deeply involved issue that has never happened before...

[Archon]

IIRC, it's quite possible that was the issue. It's been a while since there have been any posts regarding it, but there were posts where a bad/missing pcv valve created a large vacuum within the engine, and it would suck air past the gaskets creating a squealing noise.

[95naSTA]

My first thought was PCV valve.. Hope that fixes your issue.

[Bugsi]

Follow-up from three years later: Yes, that was the problem. Car still runs great. It's our spare car but we give it weekly driving. Very reliable.