Kazmon

Issue started a few weeks ago. Back then, if i ever came close to redline, something would start a spinning-type squeal from below 2.5k(?)ish rpm to idle speed. It would go away with clutch being pushed in. Goes away with any throttle. Shutting the engine off, i hear the squeal drop to 0 rpm.
Now, the squeal appears at low rpm’s and idle, without having been near redline. Throttle makes it go away still, however, clutch only makes it go away sometimes, or half as loud.

If this is throwout bearing, could it explain why sometimes when getting going in first, it’s a little shuddery? As if something is warped?

WondrousBread

Could be the air pump, it freewheels at engine speeds greater than 3000.

Free way to check: remove the drive belt for the air pump, take a test drive, reinstall it. This is a bit of a pain with the stock fan and accessories but it costs zero dollars.

Kazmon

Do you mean the A/C compressor? If so, it’s already disconnected. Otherwise, explain it to me as if i was idiot. Lol.

WondrousBread

If you look at the front of the engine, there are four drive belts (fewer sometimes, depending on options).

The outermost belt is for AC (if optioned).

Next inner belt is power steering (if optioned).

Third inner belt is the air pump.

Innermost belt is the alternator.

The air pump is on the passenger side of the engine. It's a belt driven pump that sucks air in from the filter box, then passes it to the air control valve. This valve uses certain sensors to determine when to pump this air into the exhaust catalyst (for emissions), the exhaust ports (for deceleration), or to dump it through a silencer.

Anyways, to remove the belt you need to take off the outer two belts first. It sounds like you already don't need to worry about AC, so for the power steering belt just loosen the nut on the tensioner pulley then wind out the little 10mm nut on the adjuster. That's assuming you have power steering, anyways.

Once the belt is loose remove it and set it aside.

Then go to the air pump. The way it is tensioned is sort of like the alternator, where it has a saddle mount on one side and a bolt on the other. Loosen the bolt on the adjustment slot and push the air pump to the loose side, then remove the belt. You may need to loosen the saddle mount too. Put the belt in a safe place.

Then reinstall the power steering belt and tension properly.

The reason I suspect the air pump is that it disengages above 3000rpm (which is where you say the noise goes away). It also has the air pumped into different places depending on whether you're decelerating or other things, which would be consistent with what you're saying.

I don't know if it disengages when the clutch is depressed, but there is a clutch switch for the ECU to bump idle by about 50rpm. It would not be unreasonable to assume it might do something with the air pump / air control valve too.

Anyways, that's my line of thinking.

Kazmon

Sorry to have you type all that for it to not be a solution for me. Hopefully a solution for someone else. I only have an alternator belt, air pump is blocked off. Bought it this way.
the whining/squeal seems to come from back of engine, maybe something under intake manifold?

i was driving yesterday, the squeal was present at every stoplight. But after so long it went away??? A little while later, by the time i was pulling in my driveway, it was starting again.

WondrousBread

Well the air pump was the easier option.

The next option (especially since it's coming from the back of the engine) is the pilot bearing or throwout bearing. Both of which necessitate removing the transmission for access. The input shaft bearing on the transmission might also do it.

Normally if the sound appears when pressing the clutch, it's the throwout bearing or pilot bearing. Which doesn't seem to be your problem. (Incidentally, I find throwout bearing more likely than pilot bearing from experience). Normally these are replaced together when replacing the clutch, so you may just want to do a clutch job if you get in there and find significant wear.

The input shaft bearing might be making the noise, but I've never replaced one of those. On one transmission I found particularly noisy though, there was some play in the shaft side-to-side. A bad bearing won't always create shaft play, but shaft play always implies a bad bearing.

Before you start removing the transmission though I would wait to see if anyone else has ideas.