alternator belt is screaming ..... how tight shall I go???

[bassman]

I was the guy with the charging problem and now I am charging but the belt screeches when I put it in drive or step on the gas from time to time.

I want to tighten it up but have read that overtightening can break stuff so .... how tight can I go ??

I was thinking it may be a bearing but a bearing would make noise all the time ...??? or not??

[scottxd45]

To find out if it is the belt take some soapy water or belt dressing or something and spray the belt while it squealing. If it goes away its the belt not a bearing. If the belt is squealing it is either loose or worn out. Or you could possibly have so rust or something on the pulleys.

[ls1_se7en]

I replaced everything thinking mine was a bearing or something like that...oops. I would put a good bit of tightness to that belt. Not he-man tight, but nice and snug with a breaker bar. That stopped my screaming immediately.

[WmWatt]

Belts usually chirp, bearings squeal. I'm at the public library and don't have the Haynes manual with me but it says how much play there should be in the belt. You put a straight edge across the top of the belt from pulley to pulley and then press down on the middle of the belt and measure the distance it goes down. I do it by pressing down with the end of a ruler and reading the distance at the stright edge. For a straight edge I use a small (1 foot) metal carpenter's square.
If the belt is too loose it will slip, usually make a noise, and not generate enough juice to charge the battery. The charging voltage across the battery terminals when the engine is running should be 14.7v, I think, according ot the Haynes manual.
If the belt is too tight it will eventually ruin the bearings in the alernator and the alternator will have to be replaced.

[JPT]

If it's a new belt and hasn't been slipping long, just tighten it up (assuming it's the belt that's making noise). If the belt has been slipping for a while, it might be glazed. If it is, the amount of tightness you'll have to use to stop the slipping might wear out the alternator bearing. Then it's time to get a new belt

[leapin]

^^agreed

[bravekozak]

tighten to spec

Only tighten the belt to spec. Assuming it is the proper size to the groove, try spraying some belt dressing. It is resin dissolved in a high flash solvent. It will prevent slippage.
Good luck.

[WmWatt]

Haynes Manual, page 1-2
Accessory drivebelt deflection
Used belts .035-.039 inches (9-10mm), I use 3/8 inch
New belts .031-0.35 inches (8-9mm)

[Pgh5spd]

Every time I've put a new belt on, I've had to go back and tighten it again within the first month. After that, they seem to go for a long while.

[FB71]

^^^ That's normal. The belt will stretch a bit after operation, and needs to be retensioned.

[packrat427]

I had a belt that would never stop squealing on a cold start up , or a restart .

I used a fine grit sand paper to rough up and de-glaze the pulleys , and installed a new gates belt , (not a cheapy).

The belt still squealed on start up , and worse when it was humid .

So I tightened it more and a little more , finally it quit and I was happy ..

Then when we left for Colorado , somewhere in the middle of nowhere in the state of Kansas , the middle of my water pump pulley , broke the center out of it from too much tension .

So be careful just how much whammy you put on it ..LOL

The old rule of thumb was .. in the center of the belt , it should not have more play up and down as the width of the belt around your waist.

[Safety Guy]

I'm bringing this one back because I bought a new belt at NAPA about a month ago. A few days after installation, I had to re-tighten it. That was expected.

A week or so later, it began squealing again, so I tightened it a second time. A week or two after THAT I had to do it again!!

Now, a week or so later, it is again squealing. This will be the FOURTH time I have to tighten it.

Any ideas? This is Twinstiva, who sat for three or four years. Should I sand the pulleys and install a brand new belt? Could the NAPA belt be crap?

I'm sick of tightening belts!!

Karl

[m715]

How free are the bearings in the alternator and water pump? I had an alternator that did that to me from setting too long. Still have it for emergencies, but I could NOT get that belt to stop squeeling with that one! It was one off a parts Steva that charges and all, but the bearings are just are too stiff. Hite Parts Exchange is where I got my replacement, and they are local to you. The replacement had the Ford reman stickers on it, so they must have been the authorized reman there possibly?

HTH

Michael

Michael

[Safety Guy]

Michael, that's very possible. My car sat for at least three to four years.

I have a new alt from Hite. I considered putting it on, but it wasn't the right one! When I bought it I noticed it was different. I compared it with the one on Luxstiva. I went back in and told the counter guy, who looked it up and found the picture of a "Festiva" alternator looked just like the one I had bought. So I figured someone had installed an Aspire alt on my car some time in the past.

The alternators on Lux and Twin are the same. They ARE Festiva alternators. I have no idea what I have, but it has a Mitsu diamondstar logo on the connection side.

I ended up removing my alt from the car and cleaning all the crap off it (powdered black soot). I also sanded the pulley insides. It does seem to be not as "freewheeling" as it should be. That may be the problem.

I may be on the market for a replacement alternator soon. I wonder if my '89 alt off the Mutt will work?

Karl

[m715]

The 88&89s are different. The carb models had an extra plug to power the electric choke, and were 45 amp. 89 ATX was a one off 50 amp w/o the second plug. Both looked identical. 90 has a totally different plug on the back, and as far as I know these are the same through 93.
My spare I spoke of probably looked the same as yours, black carbonish deposits covering the whole assembly. The bearings don't seem noisy, but it does not spin *freely* either.

Michael