Serpentine belt squeal

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Serpentine belt squeal

October 21, 2019, 03:58:31 pm

Our serpentine belt on the coach started squealing while we were staying in PA. At first I thought it might be a bad tensioner or water pump so i pulled the belt off and checked all the pulleys and they all spun freely without any noticeable drag. Then I went and got some belt dressing just to see if it made any difference and when I sprayed the belt the squeal went away immediately. Then it came back the next time the engine was started. That same situation happened a few times until found a new belt that had been packed away by the previous owner.

I cleaned all the pulleys off because that belt dressing is nasty stuff and replaced the belt. No more squealing after that so I went and bought another belt just to have a backup and didn't worry anymore about it.

It's been a month or so and 7xx miles since then and now the new belt is squealing again and I'm not sure what to do. I pulled the belt off and checked all the pulleys again and they all seem fine so I tried the belt dressing again and the squeal went away for about 30 seconds and then came back with a vengeance. Now it sounds really terrible and has me worried that something might be wrong somewhere that I'm not seeing.
I haven't tried the other new belt yet because it doesn't make much sense why the other one is squealing so soon.

The belt that we found and the one I bought for backup is a Gates that is 1 3/32 x 61 1/8. I'm not 100% certain that they're the correct size because I haven't found anything that says what the correct size is or isn't but they matched the old belt and fit nicely on the engine.

I was thinking that maybe the belt we have is a little too long and has possibly been stretched enough to cause some slippage and therefore the squeal but it seems adequately taut. I tried putting a 1/2" ratchet in the tensioner and applying more tension to see if it made any difference but it did not.

If anyone has any ideas we'd really appreciate hearing them.

Thanks!
Tyler

Re: Serpentine belt squeal

Reply #1 – October 21, 2019, 04:37:24 pm

Had similar issues last week.. You can look at my post but for now try removing the belt and spraying the pullies with either and brushing through with a stiff wire brush.. The edge of the pulley nearest you will hide the first couple groves so brush heavy there.. Watch for rust dust on those outside edges.. You say your pullies checked out but with engine running be sure you have no up and down bouncing on tension pullies. They should hold steady with engine at idle running..clean those pullies

Re: Serpentine belt squeal

Reply #2 – October 21, 2019, 05:07:10 pm

Quote from: Dub – October 21, 2019, 04:37:24 pm

Had similar issues last week.. You can look at my post but for now try removing the belt and spraying the pullies with either and brushing through with a stiff wire brush.. The edge of the pulley nearest you will hide the first couple groves so brush heavy there.. Watch for rust dust on those outside edges.. You say your pullies checked out but with engine running be sure you have no up and down bouncing on tension pullies. They should hold steady with engine at idle running..clean those pullies

Great tip Dub!

Here's an excellent video on cleaning the pullies using carb cleaner and steel wool, etc. He says to spray the belt also.

Jerry

https://www.youtube.com/watch?v=RUJQ271mHPs

Re: Serpentine belt squeal

Reply #3 – October 21, 2019, 06:54:39 pm

In my case the old belt looked fine, but a new belt cured the squeal. Sprays were only a short term solution.

Re: Serpentine belt squeal

Reply #4 – October 21, 2019, 06:55:44 pm

Quote from: Tom Lang – October 21, 2019, 06:54:39 pm

In my case the old belt looked fine, but a new belt cured the squeal. Sprays were only a short term solution.

Totally agree. Belt dressing should be considered "get me to a place where I can figure out what is wrong".

Re: Serpentine belt squeal

Reply #5 – October 21, 2019, 07:12:55 pm

Quote from: Dub – October 21, 2019, 04:37:24 pm

Had similar issues last week.. You can look at my post but for now try removing the belt and spraying the pullies with either and brushing through with a stiff wire brush.. The edge of the pulley nearest you will hide the first couple groves so brush heavy there.. Watch for rust dust on those outside edges.. You say your pullies checked out but with engine running be sure you have no up and down bouncing on tension pullies. They should hold steady with engine at idle running..clean those pullies

I will definitely try this because there is almost certainly rust on the pulleys and I wouldn't have thought of cleaning them. Thank you

Re: Serpentine belt squeal

Reply #6 – October 21, 2019, 07:28:32 pm

If rusted, sandpaper is your FRIEND.

Re: Serpentine belt squeal

Reply #7 – October 21, 2019, 07:34:25 pm

The belt dressing is definitely a band-aid, I just wanted to try it and see what happened. After seeing and cleaning off the sticky residue it left on everything I really don't care for it.

Re: Serpentine belt squeal

Reply #8 – October 21, 2019, 08:21:00 pm

Your welcome Tyler.... You will get it quietened down.

Re: Serpentine belt squeal

Reply #9 – October 21, 2019, 09:01:12 pm

Went through all this when I bought our coach.
I would suspect it needs a new tensioner. Solved my issue.
Same on my Jeep wrangler last year, new tensioner solved it.
Might as well replace them both, they are not expensive.
Belt dressing is a no, no on serpentine belts. Made for old V belts.
Chris

Re: Serpentine belt squeal

Reply #10 – October 21, 2019, 09:15:06 pm

The belt tensioner could be off plane. With the engine running, put an 8" long half-inch extension into the belt tensioner. Instead of increasing or decreasing the tension on the belt (which you already did), gently push the extension north, south, east and west. If moving the tensioner in one of those directions quiets the belt, you may have discovered that the tensioner is off plane. If so, you can shim it to get it parallel with the belt and other pulleys. That's how I stopped one of my belts from squealing.

Re: Serpentine belt squeal

Reply #11 – October 21, 2019, 10:02:25 pm

Chris,, my belts didn't start squealing until I put on 2 new tensioner's and 3 new belts.. Squealing belt can be a tricky egg to crack.. Any and all the above can be a culprit, been there and done it but THIS time after all the chasing and replacing the fix was deep cleaning groves on pullies.. I had no noise to begin with and reason was my water pump belt lost 2 groves and wasn't running on the rusty groves on the pulley.Only thing I replaced that didn't need replacing was a water pump..

Re: Serpentine belt squeal

Reply #12 – October 22, 2019, 02:59:10 pm

Quote from: EricFromPA – October 21, 2019, 09:15:06 pm

The belt tensioner could be off plane. With the engine running, put an 8" long half-inch extension into the belt tensioner. Instead of increasing or decreasing the tension on the belt (which you already did), gently push the extension north, south, east and west. If moving the tensioner in one of those directions quiets the belt, you may have discovered that the tensioner is off plane. If so, you can shim it to get it parallel with the belt and other pulleys. That's how I stopped one of my belts from squealing.

I did a deep clean of all of the pulleys with a wire brush, carb cleaner and a wire wheel on a drill. There wasn't much rust on any of them but they did have some buildup in the grooves. Unfortunately the squeal was still there after a few seconds of idling.

I put an extension in the tensioner pulley and moved it around like you suggested. I found that when pushing the pulley inward towards the engine but without increasing or decreasing the tension on the belt that the squealing stopped. I took the belt off and did the same thing and the pulley arm has quite a bit of in and out movement at the pivot point. I'm not sure if there is any way to shim it since it stopped squealing when pushed towards the engine.

I had looked into ordering a new tensioner when this all started and they're not too expensive so I'll probably just order a new one.

Thanks for the suggestion, it was another thing I probably wouldn't have thought to do. I

Re: Serpentine belt squeal

Reply #13 – October 22, 2019, 07:34:42 pm

Quote from: The Soft Boulders – October 22, 2019, 02:59:10 pm

I did a deep clean of all of the pulleys with a wire brush, carb cleaner and a wire wheel on a drill. There wasn't much rust on any of them but they did have some buildup in the grooves. Unfortunately the squeal was still there after a few seconds of idling.

I put an extension in the tensioner pulley and moved it around like you suggested. I found that when pushing the pulley inward towards the engine but without increasing or decreasing the tension on the belt that the squealing stopped. I took the belt off and did the same thing and the pulley arm has quite a bit of in and out movement at the pivot point. I'm not sure if there is any way to shim it since it stopped squealing when pushed towards the engine.

I had looked into ordering a new tensioner when this all started and they're not too expensive so I'll probably just order a new one.

Thanks for the suggestion, it was another thing I probably wouldn't have thought to do. I

There are two different brands. Gates and Dyco. Can't remember which brand I switched to,but different from what the factory used. Maybe someone on here can answer this.

From all I read, it was a better one then the factory used. So I changed them both. Never an issue again
Chris
Maybe search on here will reveal the brand. It wasn't expensive.

Re: Serpentine belt squeal

Reply #14 – October 22, 2019, 07:52:27 pm

Chris,

Could it have been Dayco? They have an excellent reputation and if we didn't have all Gates Green Stripe belts, Dayco would be a good replacement. Lots of race cars used Dayco belts in my time. See Dayco at: Dayco Products, Dayco Belts, Dayco Belt Tensioners

Pierce

Re: Serpentine belt squeal

Reply #15 – October 22, 2019, 07:59:58 pm

Gracerace and Pierce, are you guys talking about the belt or the tensioner? I was going to order the tensioner from Cummins. I should have ordered it while in PA because there was a seller on Ebay that had new OEM Cummins tensioners for like $68 instead of the $120 from Cummins. Oh well

Re: Serpentine belt squeal

Reply #16 – October 22, 2019, 08:23:22 pm

You can get the tensioner at NAPA

Re: Serpentine belt squeal

Reply #17 – October 23, 2019, 09:01:54 am

I have always been partial to Gates belts and Gates tensioners.

Re: Serpentine belt squeal

Reply #18 – October 23, 2019, 09:29:53 am

I ordered a Dayco tensioner from Amazon and it'll be here Friday. Thanks to everyone for the information on the dayco and gates products because I wouldn't have known otherwise. There's so many aftermarket manufacturers with such a wide pricing range that it's difficult to know which to buy.

Re: Serpentine belt squeal

Reply #19 – October 23, 2019, 10:45:56 am

Quote from: The Soft Boulders – October 22, 2019, 07:59:58 pm

Gracerace and Pierce, are you guys talking about the belt or the tensioner? I was going to order the tensioner from Cummins. I should have ordered it while in PA because there was a seller on Ebay that had new OEM Cummins tensioners for like $68 instead of the $120 from Cummins. Oh well

Both Gates and Dayco make excellent products. I've always been a Gates fan but my engine builder always put Dayco belts on the stock car engines. Probably splitting hairs favoring one over the other.

If you order from Cummins or Foretravel, expect to pay a big premium for the exact same part you can get at an auto parts store or even cheaper online. I some cases, you may even be getting an updated product from a volume supplier rather that one that has been sitting on a shelf for a long time.

Pierce

Re: Serpentine belt squeal

Reply #20 – October 23, 2019, 11:19:35 am

Quote from: Pierce & Gaylie Stewart – October 23, 2019, 10:45:56 am

Both Gates and Dayco make excellent products. I've always been a Gates fan but my engine builder always put Dayco belts on the stock car engines. Probably splitting hairs favoring one over the other.

If you order from Cummins or Foretravel, expect to pay a big premium for the exact same part you can get at an auto parts store or even cheaper online. I some cases, you may even be getting an updated product from a volume supplier rather that one that has been sitting on a shelf for a long time.

Pierce

Tensioner is what I am talking about

I personally don't buy anything from Cummins, Cat or Foretravel. I find it on Ebay normally. they charge sometimes double what I can find it for.

I know lots of people favor Amazon, it's definitely easy. But even with free shipping, I find the prices much higher on Amazon then other places like Ebay. But I admit they give good service.

As for the difference, I believe it is a bearing issue with the 2 different brands. One has Chinese bearing, and fail early, the other is German.

I am about 99% sure the Dyco tensioner is what I put on ours, after reading about the two. Not saying the Gates is bad.

I know as a tech, even on newer FT's (90's then), I replaced them regularly for customers.

Chris

Re: Serpentine belt squeal

Reply #21 – October 23, 2019, 03:40:44 pm

Quote from: gracerace – October 23, 2019, 11:19:35 am

Tensioner is what I am talking about

And the tensioner is also what I'm linking here. This the the MOST expensive Dayco tensioner I could find. Other Dayco or Gates tensioner were less expensive in a 30 second search on ebay.

110,000 on our 1993 tensioner with only a squirt of oil every 30,000 or so.

Belt Tensioner Assembly Cummins ISX QSX DAYCO 89440 | eBay

Pierce

Re: Serpentine belt squeal

Reply #22 – October 23, 2019, 05:50:20 pm

Quote from: Pierce & Gaylie Stewart – October 23, 2019, 03:40:44 pm

And the tensioner is also what I'm linking here. This the the MOST expensive Dayco tensioner I could find. Other Dayco or Gates tensioner were less expensive in a 30 second search on ebay.

110,000 on our 1993 tensioner with only a squirt of oil every 30,000 or so.

Belt Tensioner Assembly Cummins ISX QSX DAYCO 89440 | eBay

Pierce

I would be super careful. Many look the same. You want to cross reference several times to make sure you have the right one. Especially since you are switching brands.

I have my numbers, but yours will be different then our Cat

BTW, it's a sealed bearing, so not sure oiling helps. Ours had 111K miles when I replaced them. Looked original.

Chris

Re: Serpentine belt squeal

Reply #23 – October 24, 2019, 11:34:00 pm

Not sure if this is of any value or not given the different years and engines, but we had a similar problem with our '92 U225. We have the Cummins 230 and had it serviced at a Cummins shop in VA. Shortly after, we developed a horrible belt squeal. It would generally quiet down after running for 10-20 seconds or so and was worse on restarting after stopping for fuel.

It drove us crazy for months. We had it checked by numerous shops, had the water pump and tensioner replaced, and more, all to no avail.

We verified on numerous sources that the Gates belt used was the one specified by Cummins for that engine. But then...we found out that Foretravel had specified a slightly smaller belt. The one specified by Cummins for our engine is an 080620, the one specified by Foretravel is an 080610.

Keith R at MOT changed the belt and the squeal immediately went away. Oddly enough we had some subsequent work done at another shop and they, thinking the 610 was the wrong belt, replaced it with a new 620 without our knowing it. Sure enough shortly after that the squeal returned just as bad as before. Once we realized what had happened we had the belt switched back to a 610 and the squeal has been gone ever since.

Again, this may have no relation to this problem, but it might be worth checking.

Re: Serpentine belt squeal

Reply #24 – October 25, 2019, 04:13:35 pm

Got the new tensioner on and the belt was still squeaking on startup which really bummed me out. The squeak was much quieter than before but was still very noticeable. After letting the engine idle for a while the squeak and squealing has gone away. I killed the engine and restarted it a couple times and still no noise. Hopefully the problem has been solved but if it comes back i will try a shorter belt like Jeff and Deb suggested. Our belt is a 080605 and the next size down is a 080600 and it's 1/2" shorter.

Thanks again for everyone's input, I will update if the belt starts squealing again.

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