HELP!? Would belt being a smidge too loose cause it to come OFF?

toyman · Sep 21, 2007

Pokageek said:
I put some washers between the underdrive pulley today and that straightened out the belt track seemingly just fine..

You shouldn't have to do that. What U/D pulley are you referring to Alternator, water pump or crank?

Pokageek said:
So I drove it around the block and it drove just fine. Popped the hood and the belt seemed fine and not jumping around but I did notice my amps gauge studdering a little meaning maybe the belt is a little too loose or something.. But I think it is pretty darn straight..so ...

I took it for a forty mile run tonight..but I noticed a flapping sound on the bway and it did not sound normal, no I nursed it back to my house to find my temps going up, power sterring going out and my battery light coming on..

So when I got it in the driveway just b4 overheating, I popped the hood and noticed the belt was torn to shreads...

I know after the car is warmed up, I can pull the belt off the tensioner pulley by hand.

Is there any tension on the tensioner. Belt shouldn't be that loose.

Pokageek said:
I can only guess that it is a little too loose and when the car heated up it became more loose and jumped then tore itself up[/B]?

Does this make sense to anyone as a possibility? I want to try to nail it down so I don't start spending tons of money on belts..

If there have been no changes ie accessory deletions/additions why do you think that a stock belt wont solve the problem?

Pokageek said:
So I am going to try Mike's suggestion of getting an idler pulley in place of the tensioner pulley to tighten some slack up.

Are they a different size and are they really interchangeable?

Pokageek said:
Also, when I try to sping the idler it turns but does not SPIN, like the bearings are a little worn.. same with the tensioner pulley.. Is theis NORMAL?

They should turn freely and smoothly. I cant say that they "spin".

Pokageek said:
Could this cause a belt to JUMP?

Not likely but loose and worn will as well as misalignment.

1slow95 · Sep 21, 2007

I would go a 1/2" shorter on the belt and swap the tensioner pulley like I mentioned before. I think I still have the box from my belt, I'll look for it tomorrow and let you know the length. You've deleted the smog and A/C, right?

Something I forget to mention before about the idler pulley, I got it from Advance and they changed the design of it so it's too wide to bolt in place of the tensioner pulley. What I did was swap my old idler pulley to the tensioner and used the new one as the idler. If you can find someplace that sells the correct size I would go ahead and pick up 2 of them. Mine spin pretty easy, so I would say it's about time to replace yours.

Pokageek · Sep 21, 2007

1slow95 · Sep 21, 2007

toyman said:
Are they a different size and are they really interchangeable?

Yes they're different sizes, and yes they're interchangeable. With the smog pump deleted, the belt has almost a straight shot from the alternator to the crank and the tensioner doesn't move far enough to do it's job properly. Installing a larger pulley will fix that problem.

Pokageek · Sep 21, 2007

1slow95 · Sep 21, 2007

Pokageek said:
I just caught your post Mike. Yes, I tried to find an 84.5 but they don't seem to make one..or not at salvo..does anyone know if they make that size? I was going to get the idlers from 5.0 resto..

Oh, .. also, you have a mack underdrive, stock water pump and mac alt pulley right? I have a rebuilt alt with what looks like a larger pulley than stock alt, frpp water pump underdrive and frpp crank under drive..

I am wondering if it would be smarter to just match someone like your setup and know for sure I won't go thru 9 $36 belts..

I got my belt at Advance, and I'm thinking 84.5 sounds right...I'll find out tomorrow if I still have the box.

I have all BBK pulleys(alt, w/p, crank). Only my power steering and idlers are stock. I didn't have any belt alignment issues, except for me being a dumbass and not tightening the balancer all the way.

Yeah, the tensioner will knock with the smog pump deleted and the stock size pulley on it.

Pokageek · Sep 21, 2007

final5-0 · Sep 22, 2007

Keith

Sure sounds like something somewhere is not in alignment

Of course you don't want it too loose but something is interfering
with the belt enough to do it damage at higher rpm it seems

If Mike had no probs ... seems like you just have to see what is
different about your setup

Good Luck my friend

Grady

go-stang5.0 · Sep 22, 2007

I have never heard of having to shim an underdrive pulley. I would make sure your crank bolt is tight and that your balancer is not backing off the crank.
It's probably not but just make sure.

95strokerPSU · Sep 22, 2007

My belt would "walk" off the pulleys after two mintues of driving when I got rid of ac and smog. Turned out that the PS pulley wasn't seated all the way.

I don't think the 1/2" shorter belt is going to be the fix, I'd bet one of your pulley's is not in line with the rest.

1slow95 · Sep 22, 2007

I guess I was wrong, my belt is 85".

Here's some pics of my pulley setup.

And here's the difference in size between the idler and tensioner pulleys.

Pokageek · Sep 22, 2007

95strokerPSU said:
My belt would "walk" off the pulleys after two mintues of driving when I got rid of ac and smog. Turned out that the PS pulley wasn't seated all the way.

I don't think the 1/2" shorter belt is going to be the fix, I'd bet one of your pulley's is not in line with the rest.

UPDATE:
Thanks everyone. hmm..., 95, how do you seat the ps pump pulley? Is that those 3 bolts? they are tight. I noticed it does have about a 1/4 inch wobble in the ps pulley.. and it has some play front to back as well. Could that small amount of play do it? How do you fix that? Why does it only throw the belt after the car gets good and hot though?

Final: I tested it at higher rpm's sitting. It stayed on..I am thinking the belt gets loose as the car/belt heats up b/c I don't see anything out of algnment. I will rechck again.

Mike thanks for the pics. Weird but after looking at yours, I noticed there is a good amount of space between your crank pulley and your balancer. I had my pulley on like tht and the belt kept flying off immediately...so i reversed the FRPP crank pulley , which looks a lot like yours and then it stayed on..

On the ques of the crank bolt, it is tight. I put the shims in to line up the under drive crank pulley even with the others. B4 I did that, the belt was ribbing around the crank pulley and riding incorrectly.

As to the diff between mine and Mikes;
#1 I have frpp underdrive water pump and crank pulleys (they might be slighly diff diameter).
#2 I have a a rebuilt motorcraft alt from salvo auto parts. The pulley on that is definitely larger than my old one.

As Mike said though..without having an idler pulley on my tensioner..is it possible the already loose belt is coming off because of the lack of tension and heating up?

toyman · Sep 22, 2007

Pokageek said:
Thanks everyone. hmm..., how do you seat it? Is that those 3 bolts?

I tested it at higher rpm's sitting. It stayed on..I am thinking the belt gets loose as the car/belt heats up b/c I don't see anything out of algnment. I will rechck again.

Mike thanks for the pics.

On the ques of the crank bolt, it is tight. I put the shims in to line up the under drive crank pulley even with the others.

I think that is the troubling aspect. An U/D pulley should just be a bolt on swap with the original crank pulley, shimming should not be necessary. Since everything else hasn't moved or been altered all the other pulleys, alternator, tensioner, idler, water pump and power steering are presumably aligned. I wondering if it's possible to position a laser light from from the PS pulley to the crank to confirm alignment. Of course if the problem is also tension related you have two separate issues.

Pokageek · Sep 23, 2007

nmcgrawj · Sep 23, 2007

I doubt the idler not spinning freely causes it to jump. Its going in a straight line so i'd think if anything it'd burn the belt, i mean the thing would literally have to seize up completely and not spin at all before i can imagine it causing the belt to jump off like that.

That power steering pump wobbling like that sounds ilke more of the culprit. Rev the motor and watch the belt, you should be able to see it "walk" across the idler and tensioner pulleys, and the water pump maybe, and that can help u find whats causing it.

Pokageek · Sep 23, 2007

Ok. I will do that. BTW the idler is just about locked. I checked it and it is nasty.

final5-0 · Sep 23, 2007

Well ... There you have it Keith

You know these things are not supposed to be hard to turn
or
Wobbly

Yes ... I understand ... If it ain't one thing ... its another

I bet when you get these two things cleared up the prob goes away

Good Luck

Grady

Pokageek · Sep 23, 2007

Ok. Is it the pulley or the pump or both? .. I mean, if there is play front to back?

Heres the thread on pulling it.. http://forums.stangnet.com/showthread.php?t=661948&highlight=power+steering+pulley

95strokerPSU · Sep 23, 2007

I know my pump shaft has a little bit of play (in and out) but not a 1/4". It might be time for a new pump?

But before you go and buy parts, I'd really look into the washers that you're using behind the u/d pulleys. It sounds kinda like a rig job and it could be moving the pulleys out of alignment.

HELP!? Would belt being a smidge too loose cause it to come OFF?

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