Cat 3126 shredding serpentine belts

[Carl Boger]

My 1998 Beaver Patriot with a Cat 3126 and a rear radiator has shredded 2 serpentine belts in about 7000 miles.
The first time I had just reached a campground just south of New Orleans, about 750 miles from home.  Had run fine until reaching the campground then suddenly ran hot.  I had a used belt with me so I replaced the belt and I was back on the road.   The Belt was totally gone leaving just shredded material behind. Bought a new belt outside of Atlanta and then installed it.

That lasted right at 7000 miles and a little over a year until yesterday.  Coming home on I85 about 10 miles from the SC line and having just fueled up, the coach suddenly ran hot and derated.  I pulled over on a exit, and checked.  The belt was gone,but shredded pieces of the belt were around the pulleys or laying in the engine compartment.   Having spare belts I replaced it, before the engine had cooled, but I was in a hurry.  I first had to pull all the shreds of the old belt out and then putting the new one on was the easy part. 

So my question is does anyone have any idea why this is happening?  Belt was a NAPA 25 080710HD.  Pulleys and grooves appear good.  Belt seems to run true.  Has anyone run into this in the past?  Alternator is new as is the AC compressor. 

I did run through a debris field of shredded tire from a Tractor trailer that was maybe 1/2 mile in front of me when his LF blew and he ended up on the rim.  I didn't think that I had hit anything, but who knows.  That could at least explain this.

I hope to get it in a local shop soon as I really can not get to the area to do a proper inspection and evaluation, or I'd just rather pay then do all the work involved in removing the rear radiator. 

I would appreciate any insights before I leave for a 1000 mile trip in Nov.

                                                               Thanks Carl



 

[Fred Brooks]

   Carl,

I ran into that on my summer vacation in 2024. I replaced the a/c compressor and it looked fine when I installed it. After shredding 2 belts, I decided to do an in-depth alignment check of all the belt pulleys. On my coach, the serpentine belt keys off of the bottom crank pulley. I went to HD and purchased a flat stock steel 1" x 1/8 x 4'. Holding it on the crank pully I aligned it with the Idler, alternator, tensioner pulley, and then the a/c compressor clutch pulley. Everything was ok except the a/c clutch pulley. It was off 3/16". Turns out when I installed it, I put the spacer washers on the wrong side of the cradle mount. I relocated the compressor correctly and all is good. Hope you find it, Fred

[Eric Maclean Co-Admin]

Carl
As Fred described check the pulley alignment first if you replaced both the alternator and the A/C compressor make sure they both have the proper pulley on then ( count the groves on the pulley ) if they ore too narrow or not aligned properly you will have belt issues.
Next with a rear rad I assume you have a belt driven cooling fan check it for bearing slop and rumble a belt issue if the bearings are going bad..
Next check the belt tensioner and any idler pulleys for bearing issues.
And finally take a real good look at the spring loaded belt tensioner if it has one, they tend to fail in a couple of ways  they will get seized or sticky and not move through their full travel second the center pivot will get worn allowing the tension arm to deflect which tilts the pulley which in turn allows the belt to misalign and or roll the belt off the other pulleys which will cause the shedding you describe and of course a weak spring in the tensioner will also cause issues with belt chatter and slipping .
Anything that can cause the serpentine belt to misalign or slip will be catastrophic to the bell considering the fan assembly can require upwards of 45 horsepower to drive at highway speeds..

Hope this helps
Eric

[Richard Davis]

I agree with the things that Fred  and Eric have said.  The only other thing I would check is the grease zerk behind the fan pully on the 3126.  Most people do not even know it is there and it does not get greased.  It is hard to see.  You have to be looking straight down on the back of the engine to see it.  Because it got overlooked, CAT changed the design when they went to the C7 and used a permanently greased bearing.  Anyway, if that bearing is starting to seize because of lack of grease, that could cause your belt problem.  Good luck.
Richard   

[Carl Boger]

Thanks for everyone's responses!

I took the belt off today and made sure that all the pulleys felt smooth.  I have not used a straight edge like Fred suggested, but will.  I did watch the belt running and it appeared to track straight, but that doesn't mean it actually does.

As for the zerk, well I will have to look for that one.  Not a problem.

I actually just relocated the MH today to a friends property since I am having some concrete work done here.  So now instead of being right here to work on its 30 miles away.  I drove it down there today with no issues.

I will double check the pulley's grooves, but I believe they are correct.  Since I have owned it I have replaced the AC compressor, the Alternator, and the Water pump.  Thankfully the water pump has its own separate belt.

Thanks for the ideas, I will see if I can get things lined up better.  Worse case maybe I can get another 7K before another belt lets go.