Drivetrain Whine / Squeal

[ahendy]

I've got an odd one that I'm struggling to diagnose..

Sometimes, and I mean sometimes, about 10-15 minutes into a drive, I'll begin to hear whine/squeal. It's relatively high pitched, constant in pitch and volume, and does not change with speed, revs, gear, acceleration, etc. Sounds like someone saying "Weee-oooo-eeeeeee-ooooooo" in a very high pitched tone. I cannot pinpoint where it's coming from but I believe it's somewhere in the rear.

Whenever this happens, I pop it into neutral, turn off the AC/heat and radio and try to see if I can do anything to change the sound in any way. But I can't... except if I come to a stop.

If I come to nearly a complete stop (3-5 mph), the noise will abruptly stop, and doesn't ever return during the drive. Sometimes it won't even return the next drive or the one after that. But eventually it will happen again, with the same symptoms, and the same method to get rid of it entirely.

To be clear.. it's faint. In fact at high enough speed, engine, exhaust, and road noise drown it out pretty well. But on smooth roads, lower speeds, and windows down, it's clearly audible and clearly.... odd.

Some thoughts I've had:

Brakes? Doesn't sound much like brake squeal, and modulating brakes don't seem to change it at all until I get to a complete stop

Belts? Nope.. doesn't change with engine speed, stays constant in volume and pitch even at idle until car is stopped

Bearings? Maybe?

Any idea what I might be facing here? Everything else about the car works exactly as expected and I have no other issues. It's well maintained regularly and is mechanically solid. But I just can't, for the life of me, get to the bottom of this...

[red69]

Sounds like a bearing could be the throwout or pilot bearing.

[ahendy]

Both throwout and pilot bearings were replaced when I had my clutch done about 1500 miles ago. I'm fairly certain that this issue occurred before that work was done, but I had only owned the car for a very short period of time and drove it very little before I had the clutch done, so I can't say with 100% certainty.

If it were a throwout or pilot bearing, wouldn't it change with engine speed? And wouldn't it change whether the car is in gear or in neutral?

[darrin]

what year's your car and where are you located? my 86 Carrera had an issue where the diaphragm on a hose designed to let warm air into the throttle body failed, causing what I'd describe as a kazoo-like sound from the right-hand rear corner of my car until replaced.

[ahendy]

It's an 88.. and I'm in TN..

Was the sound intermittent as I described? Hard to imagine that it could be that and not be related to engine speed.