Serpentine belt idler or adjuster pulley noise

[chunker]

Girlfriend says she can hear an occasion high pitched squeal/scraping noise coming from the engine compartment. Being of advanced age and older ears, I can't hear it. It's reportedly when accelerating from slower speeds, stops when cruising or decelerating. One time I had her push the throttle while I listened at the outside off the engine compartment and I think I could hear something and in the vicinity of the serpentine belt adjuster. But because of all the other noises, couldn't be sure of it or where it was. I have looked at the belt and it looks pretty good, but it's a few years old.

I can loosen the tension adjuster but unfortunately will take another person to remove the belt from the alternator so I can check the idler pulley and adjuster for play and noise. Per chance is there a locking hole on the tensioner that when I loosen with the breaker bar I can slide a pin in to hold it's position. Didn't see any mentioned in my research about belt removal.

I did try applying a small amount of penetrating oil around the axels for the items but don't think it did any good since I really can't get it where it might be needed.
Anyone have any other thoughts.

[70ChevelleSS]

I've never seen a way to pin or lock a tensioner once it's pulled back. If you can pull the tensioner back can't you just slide the belt off of it's pulley? Then release the tensioner and the belt should be loose around all other pulleys.

[mackwrench]

The tensioner doesn't have a hold in position deal, you'll need to get belt off.

If you're coach still have the OEM tensioner, chances are that's your noise.

With engine running using a spray bottle of water, spray some on belt. If noise temporary goes away, then you have a misaligned pulley, probably due to worn tensioner or idler pulley, if noise get louder, the tensioner is bad...

I posted this a few thread ago, but it's got some good information about the 1 min mark. Best practices are to replace belt and tensioner as a set as they both maintenance item. Interesting to hear that the belt tensioner cycles a BILLION times in a 100k miles....

https://youtu.be/fFN3pr-OHSQ


Here's a short video on belt noise diagnosis
https://youtu.be/MUnftyDpfv4

[nehog]

Originally Posted by 70ChevelleSS

I've never seen a way to pin or lock a tensioner once it's pulled back. If you can pull the tensioner back can't you just slide the belt off of it's pulley? Then release the tensioner and the belt should be loose around all other pulleys.

Some (rare!) do have a pinning hole.

In my bus I used a long ratchet, and some cord to tie it off to put on the belt. It worked, and the idea came from someone who suggested a strap. I just realized that a strap was overkill and used the cord instead.

[FIRE UP]

Well,
The OP doesn't say what engine he has but, on our '04 Itasca Horizon 36GD, we have the C-7 330HP CAT. And, while I had the radiator and the CAC out, I goofed around with the serpentine tensioner and, found out something that was to me, kind-a odd. It's probably done on a regular basis but, to me was just different. I found out that there are TWO, back to back, twin bearings in there. I pressed them out which, was not very hard at all.

I mic'd them up and found out that they are stock bearings at many regular auto parts and specialty hardware stores like Grainger. And, the idler bearing was the exact same bearing. So, I zoomed down to our local Grainger and picked up three of them for a whopping $24.00. The pulley was in great shape and the spring tension was still very strong. This was all done at about 45K miles.
Scott

[chunker]

Thanks for the replies. Scott a Cummins ISL with side radiator. When I am under and and releasing tension with the breaker bar, I can't reach the belt to slide it off the alternator. From the back I can see but doesn't look like I can get a wrench on it. I thought about bracing the breaker bar and will explore that option.

I've got between 55-65K miles on the coach. I give that range because one of the ECU relays quit sending mileage info to the dash odometer, trip works but not total. Read 5500 miles. (Trip 2 shows 13,000,000+) Another issue. At any rate I suspect the belt and tensioners are stock. GF coming over today and I'll enlist her assistance.

It's not likely belt noise per se. Not that type squeal. I'll look again for a pinning hole. Spring tension for the tensioner quite strong so it's not weak. I presume from what I remember, the idler pulley is bolted to the bolt as is the tensioner. I imagine those bolts are quite strong.

I haven't researched it yet but are they secured with thread locker?

[chunker]

With a little help from my friends I was able to get the belt off and the adjuster and idler pulls all turn freely. I did shoot a bit of lubricant to the adjuster bearing to see how that works. After putting it all back together she thinks the squeal is coming from the large crank pull, water pump I suppose. I can't hear though and everything sounds OK to me.

Next week we have a short trip down to the bayou so we'll see how that sounds. I do have some belt dressing so maybe I'll investigate using that as a "listen see". In January I will be preforming the annual servicing, oil filters, etc, and I'm going to replace the belt. I may pull the tensioner and more thougfhrly inspect the bearing and replace as necessary. There are 2 idler pulls and I don't see how they come off, no bolt on the end of the shaft.

[Motor7]

Different chassis, but I had angry sparrow noises & tried the spray on the shaft's trick too....it did not work either. Replaced the belt, tensioner and Idler & all is quiet now. 64K miles on it and they appeared to be all original parts.

[Monacoach]

Ours chirped at idle until belt broke off. New belt installed and no more chirping.

[LETMGROW]

Originally Posted by drwwicks

With a little help from my friends I was able to get the belt off and the adjuster and idler pulls all turn freely. I did shoot a bit of lubricant to the adjuster bearing to see how that works. After putting it all back together she thinks the squeal is coming from the large crank pull, water pump I suppose. I can't hear though and everything sounds OK to me.

Next week we have a short trip down to the bayou so we'll see how that sounds. I do have some belt dressing so maybe I'll investigate using that as a "listen see". In January I will be preforming the annual servicing, oil filters, etc, and I'm going to replace the belt. I may pull the tensioner and more thougfhrly inspect the bearing and replace as necessary. There are 2 idler pulls and I don't see how they come off, no bolt on the end of the shaft.

Please DO NOT use any belt dressing on a serpentine belt. This will cause the belt to stick and it will break quickly.
Lynn

[vito.a]

I had a loud belt squeal during initial start up. I replaced the idler pulley, the tensioner pulley, and installed a new Gates HD Kevlar belt. The squeal continued, but not as bad.
Then I discovered my engine start batteries were slowly draining down and not being charged while plugged in. The Intellitec Big Boy solenoid was not closing and charging the chassis battery. I took the solenoid apart and cleaned it and resurfaced the contacts. Now the chassis batteries stay charged and it doesn't kick the 270a Leece Neville alternator into full output on initial startup.
Oh well, it needed a new belt anyway.

[RKins]

I had a bad bearing (I assume) and replaced the tensioner for $75 and now it's fine.

[99dart]

Just as a side note, You can repack the bearings on the idler/tensioner pulleys if you are between a rock-ana-hardplace. Carefully pry the seal off the bearing, clean with solvent/gas and repack. Then pop the seal back in place. I've done this a couple times on my Dodge w/a 5.9L Magnum engine. I was doing other work on it at the time and thought Hmm... wonder if? It has worked out great!

[jumpingjack]

Originally Posted by drwwicks

With a little help from my friends I was able to get the belt off and the adjuster and idler pulls all turn freely. I did shoot a bit of lubricant to the adjuster bearing to see how that works. After putting it all back together she thinks the squeal is coming from the large crank pull, water pump I suppose. I can't hear though and everything sounds OK to me.



Next week we have a short trip down to the bayou so we'll see how that sounds. I do have some belt dressing so maybe I'll investigate using that as a "listen see". In January I will be preforming the annual servicing, oil filters, etc, and I'm going to replace the belt. I may pull the tensioner and more thougfhrly inspect the bearing and replace as necessary. There are 2 idler pulls and I don't see how they come off, no bolt on the end of the shaft.

Hi I use baby power on belt stop the noise might let you know if it Belt or bearing