Here's a head scratcher for you. I know it's a 300ZX, but I though I'd see if anyone has an idea.

1985 300ZXT 5-speed

A sequence of events led to a timing belt break (head bolt broke and lodged under the cam) and susequent head removal (no damage) and a replacement of the head gasket, new timing belt and tensioner. I replaced the water pump and all 3 drive belts as well. Everything went well and the car started right up and runs fine.

Now I've got a squeal that sounds like a bearing going/gone bad when it's cold. It lasts for about a minute and then goes away.

I've re-checked all the belts

I pulled the A/C belt (V-belt) to see if was the A/C idler pulley. Still squeals

I pulled the P/S belt (V-belt) - Still squeals.

I puled the Alt/water pump belt (ribbed belt) and started the car - No squeal.

I manually spun the alternator pulley and the water pump pulley. I found a little play in the water pump (new) so I removed it and put the old pump back on - no squeal at start up and nothing while the car idled and warmed up.

The next day, the squeal is back in the morning.

Could it be the fan clutch? It was laying flat when it was off the car? The hayden web site talks about bearings in the clutch.

The alternator was not squealing before so that's my last suspect.

Any ideas? I'd like to figure it out rather than replacing part after part.

Do you have a stethoscope? If not , a long screwriver or 3/8" ratchet extension will do. Being VERY CAREFULL, touch the various suspects; alternator, water pump, associated pullies, etc. with the motor running. You will quickly determine the source of the squeal, or at least eliminate the innocent.

Believe it or not, I have also encountered a vacuum leak that made a high pitched squeal, just like a bad bearing. You might want to check the tightness of all your manifold bolts if you can't find any other source.

But the long screwdriver trick should help to track down the source of the sound.

This may or may not be what you're experiencing but a couple of years ago I was chasing down a squeal like that in my 810 and it turned out to be a very small leak in the AC vacuum bottle. Replaced the bottle and the sound has been gone ever since.