Serpentine belt coming apart

[BirdTRD]

Ok, so I replaced my serpentine belt last month, <500 miles ago and it's doing the same thing. It's looks like it jumped a groove forward and tore the front edge of the belt apart.
The first belt was installed with the Edlebrock kit over 2 years and >20k miles ago with no issues. Now 2 belts in a month with the same front edge damage. All of the idler pulleys have a tiny bit of wiggle to them but I don't know what's an acceptable amount or if i should be looking elsewhere. (tensioner perhaps)
Any suggestions would be appreciated. (besides the obligatory "should've bought a ......) Thanks

[gtengr]

I would think it's either the tensioner or the bearing in one of the pulleys. How easy was it to move the tensioner when changing the belt?

[Grady]

So the original belt with the SC lasted 20K? Now the 2 new belts go bad within 1 month. I would look at what has changed. First is obviously the belts. 2nd is the installation procedure. 3rd would be tensioner, then verifying pulley bearings/alignment.

[mswbrz]

I would def think it would have to do with the tensioner perhaps wearing out, losing tension and then allowing the belt to have some
Slack causing it to jump a groove and cause it to get eaten up but I'm sure you have thought the same .
The idler pulley at the dealer is about 76 bucks (Subaru dealer in Modesto ca ). I would start with that since they are automatic tensioners.
Are you certain you have the right size belt ? I use gates belts for my jrsc and didn't change it up until recently after being on for about 3 years .
I may be wrong but let us know what you figure out



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[BirdTRD]

Originally Posted by gtengr

I would think it's either the tensioner or the bearing in one of the pulleys. How easy was it to move the tensioner when changing the belt?

I was under tension...how much exactly, I don't know, I used a 1/2 drive socket wrench with a piece of pipe on the end so I wasn't fighting it.

Originally Posted by Grady

So the original belt with the SC lasted 20K? Now the 2 new belts go bad within 1 month. I would look at what has changed. First is obviously the belts. 2nd is the installation procedure. 3rd would be tensioner, then verifying pulley bearings/alignment.

The original SC belt failed last month and I replaced it, now the new belt has failed, currently waiting for the second replacement belt, so the belt was only replaced due to failure with a Continental Elite Poly-V belt. Installation was done with just a wrench for the tensioner and my hands, no tools or prying on the belt.
I suppose if the tensioner has "weakened", that may allow for the belt to jump a rib and rip itself apart like it did, but I think I'm leaning more towards the idler bearings getting a little sloppy allowing the belt to walk. I just hate to throw parts at the problem but there's nothing super obvious at the moment.

[BirdTRD]

Originally Posted by mswbrz

I would def think it would have to do with the tensioner perhaps wearing out, losing tension and then allowing the belt to have some
Slack causing it to jump a groove and cause it to get eaten up but I'm sure you have thought the same .
The idler pulley at the dealer is about 76 bucks (Subaru dealer in Modesto ca ). I would start with that since they are automatic tensioners.
Are you certain you have the right size belt ? I use gates belts for my jrsc and didn't change it up until recently after being on for about 3 years .
I may be wrong but let us know what you figure out

Do you know if there is a spec on the tensioner tension and how to measure it?

[ls1ac]

I found on an earlier car that the make of the belt made a difference. Is the replacement the same manufacturer.

[Grady]

Originally Posted by BirdTRD

The original SC belt failed last month and I replaced it, now the new belt has failed, currently waiting for the second replacement belt, so the belt was only replaced due to failure with a Continental Elite Poly-V belt. Installation was done with just a wrench for the tensioner and my hands, no tools or prying on the belt.
I suppose if the tensioner has "weakened", that may allow for the belt to jump a rib and rip itself apart like it did, but I think I'm leaning more towards the idler bearings getting a little sloppy allowing the belt to walk. I just hate to throw parts at the problem but there's nothing super obvious at the moment.

When bearings go out they can cause some harmonic vibrations that can make belts do weird things. I would feel each pulley, accessory drive when the belt is off to see if any of them have slack or sound weird.

[Ultramaroon]

The belt will slacken upstream of the blower pulley for a moment when the engine sharply decelerates from a high rpm, like when dumping the clutch too early on an upshift. This is from the blower inertia continuing to yank on the tensioner after the crankshaft slows. Undamped tensioners are not good at countering this effect.



Have you changed anything in your driving style that might exacerbate that situation?

[humfrz]

Yep, it sure does look like something is causing the belt to run a notch off center.

Is there a "right" and "wrong" way of installing the belt? I

If so, are you sure you put it on right?

I'd suggest that you move the belt over a notch (to center it), then have someone else start the car while you watch the belt to see if it moves sideways. If it stays in place at idle, rev up the engine and see it moves over.


humfrz

[mswbrz]

Originally Posted by BirdTRD

Do you know if there is a spec on the tensioner tension and how to measure it?

Since the tensioner is automatic their is no certain spec I'm aware of . I gave no idea on how to check the tension either bro :/


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[BirdTRD]

Originally Posted by ls1ac

I found on an earlier car that the make of the belt made a difference. Is the replacement the same manufacturer.

Honestly, I don't know what brand was sent with the Edlebrock kit, that was installed over 2 years ago and no issues up until a month ago.

Originally Posted by Ultramaroon

The belt will slacken upstream of the blower pulley for a moment when the engine sharply decelerates from a high rpm, like when dumping the clutch too early on an upshift. This is from the blower inertia continuing to yank on the tensioner after the crankshaft slows. Undamped tensioners are not good at countering this effect.
Have you changed anything in your driving style that might exacerbate that situation?

I have switched to my left hand recently but what's that got to do wi.....oh wait, you said exacerbate....never mind. But no, nothing has changed in my driving style and no clutch to dump.

Originally Posted by humfrz

Yep, it sure does look like something is causing the belt to run a notch off center.

Is there a "right" and "wrong" way of installing the belt? I

If so, are you sure you put it on right?

I'd suggest that you move the belt over a notch (to center it), then have someone else start the car while you watch the belt to see if it moves sideways. If it stays in place at idle, rev up the engine and see it moves over.

humfrz

I don't think the belt is directional....
For now, I cut all the "bad" parts off the belt so it's running with 4 ribs instead of 6. I don't see it trying to walk at idle so I'll need to get someone on the accelerator.
I checked on the new belt several times after I installed it and no problems.
I had just made a 180 mile trip the day before, it was cold and rainy so I actually took it easy, got home, no issues. Started the car the next morning to warm it up, sounded fine, about 10 minutes later I heard what I initially thought was large rain drops or small hail smacking the hood, but when I looked outside, it was just drizzling. That's when I realized it was the belt slapping the under side of the hood again.
I'm going to try to check pulley alignments today and make sure everything accessory and bracket wise, is secure.

[humfrz]

[quote=BirdTRD;3166188]
Good plan to take the belt off and check all pulleys for play.

Please let us know what you find out.

Back-in-the-day, back-on-the farm, we learned real quick on how to eye ball the lining up of belts. About one slap up side the head with one of those long belts was all it took to learn that. With no "V" and no ribs and grooves, it didn't take much for a flat belt to slide off a pulley.

As a young boy, it was my job to sit on a stack of bags of grain and watch the belt and pulley. If I saw it creeping off, I was to wave my arms and someone would realign the tractor.

To ward off boredom, I would catch grasshoppers and set them on the belt just before one of the pulleys to see if they could jump off before they got squashed. -


humfrz

[Summerwolf]

Weak tensioner

Pulley has come out of alignment

Always had good luck with "green stripe" belts in applications needing extra strength.

My guess in that order. Tensioner has extra work it's doing and you have now introduced non factory pulleys.