Squeaky alternator on 98 Ford Windstar

Mark opined in news: snipped-for-privacy@4ax.com:

BAd alternator bearing USUALLY dont squeak. Sound more like it might have gravel in it. When that sound is coming from the alternator area, it usually is a loose or worn belt.

In SOME cases the alternator may be putting out a LOT of current or going bad, the belt will tend to slip at the alt causing squeak.

Try letting the tensioner loose to tighten the belt first or just change belt.

On some engines there are both a tensioner and an idler pulley, make sure the one you're looking at is mounted on an arm... loosen the bolt holding arm to engine then use the pulley bolt to swing arm and loosen belt. Some tensioners have a square hole to use a socket drive extension

The alternator starts out quietly, then starts to chirp as it warms. Finally it gets loud but still chirpy. The sound seems like it's in rhythm with the shaft's rotation.

Just before this posting, I hit it again with the WD40. I couldn't get it behind the pully because the clearance was too small. I did try to keep it from overspraying and a hit right at the pulley hub makes the sound go away.

The sound is more metallic than the usual belt slipping sound.

I'm 99.99% sure it's the alternator itself, not the belt.

The diagram on the engine sticker says I'm looking at the tensioner. Another forum suggests that the tensioner is spring loaded - is there a trick to getting the tension off? There's a central hex nut - is that it or is there another point?

-M

On my 95 windstar I had to change both the tensioner and idler pulleys to stop a similar squeal. It would squeal at idle only, in cold weather. As soon as you touch the throttle, the squeal would stop. The repair lasted about 6 months and now it's back. I don't think much of the Dayco parts if they don't even last a year.

Get a manual - it shows how. The CD from Popular Mechanics (Alldata) from AutoZone or a paper manual from the same place is worth the $15-$20 for this type of help. If it is a single, wide, serpentine belt, it probably has an automatic tensioner, spring loaded. I think Ford uses ball bearings in the alternators... swap the belt first or squirt some silicone spray on it while running.

My Crown Vic made an awful sound after starting on cold mornings and I looked everywhere but it would quit before I could find it. A new belt and it hasn't done it since.

PoD

A squirt of silicone spray on a serp belt will stop squeaks. Don't use any other stuff like WD or belt dressing, tho. I can't remember where I learned this but it was a very trusted source and works well with no loss of belt performance I can detect.

PoD