Help - Belt Squeals Only During Startup - Already Searched

[jtfairlane]

My '89 5.0L Mustang has developed a very annoying habit recently. Every time I start the car, the belt squeals badly, but ONLY during startup. Specifically, right when the motor starts (not the second or two while it is cranking). It doesn't squeal at all while the motor is running.

The serpentine belt that was on the car was old and the reading on the tensioner face was way out of range, with the tensioner almost pointing straight down, so I replaced the belt with the correct length Motorcraft belt. With the reading on the tensioner face now back in the correct range, it was still making the squeal.

Yesterday I raised the tensioner pulley slipped off the belt, and spun the tensioner pulley by hand. It was rattling. I removed the tensioner pulley and shook it...very audible rattle. I surmised that the pulley bearing had gone bad, so replaced it with a metal Goodyear brand pulley from the local parts store. The squeal is still there! Maybe even a little worse.

I thought I fixed it for sure with the tensioner pulley, I mean, what are the odds that you have a belt squeal, the tensioner pulley has a bad bearing, and that turns out NOT to have been creating the squeal?

IDEAS/thoughts?

 

[Mustang5L5]

Did you try shooting a little WD-40 into some of the bearings to see if that helps?

Sometimes a bad alt pulley bearing can cause a squeal

 

[jtfairlane]

Sometimes a bad alt pulley bearing can cause a squeal

Correct me if I'm wrong, but I don't believe the alternator pulley has a bearing, but rather the bearing is a part of the alternator. In either event, my 3G Alternator and Pulley are brand new (not rebuilt or remanufactured).

 

[Mustang5L5]

Correct me if I'm wrong, but I don't believe the alternator pulley has a bearing, but rather the bearing is a part of the alternator. In either event, my 3G Alternator and Pulley are brand new (not rebuilt or remanufactured).

Well yes that's what i meant. The bearing inside the alt can go bad and somethings squeal. A little shot of WD-40 can tell you if that is the cause

 

[HISSIN50]

I'd remove the belt and check every accessory (do it first thing in the morning before the car is started - or when you know it will otherwise make noise at start-up).

The Smog pump (if applicable) and PS pump are very likely to be noisy for a second upon start up.

Good luck.