Surpentine belt failure question

[Monacoach]

two scenarios just wondering which one is more likely to destroy the belt.
1 putting on the wrong sized belt ( to small) so very tight. drive 30o0 miles
or
2 routing the smooth side of the belt around a ribbed pulley for aprox 200 miles.

I did number two then number one respective and the belt lasted maybe 3000 miles before ripping apart.

a diesel mechanic told me number 1 was most likely the culprit.

[Scarab0088]

I would agree with you...
#2 should be most destructive. Several pullies would be grooved and therefore plowing the smooth side of the belt with every turn.

#1 should be less destructive since the belt, despite being smaller than recommended, was still able to span all the pullies* and fit under the tensioner.

But...if this was the same belt in both scenarios...#1 would exist no matter the side of the belt up/down (#2).

*If the belt was so small that it didn't fit the full run, some pully must have been skipped...right?

Safe travels

[wa8yxm]

I would say too tight is #1..

My belt only half failed.. Yup, split right down the middle along a rib line and 1/2 broke and got wrapped around everyting.. FIrst chance I got I spent like 2 hours on my back with cutters cutting the failed part out

Took a mechanic less than 30 minutes to replace it the next day.

[Monacoach]

Thanks for the input guys. I made a mistake it was actually the ribbed side of the belt going around the smooth tensioner and it was loose. After going around the fan pulley instead of dropping down to the water pump they routed it straight across to the alternator then down to the ac then the waterpump and then around the tensioner pulley. The belt is not supposed to go around the tensioner as apposed to one side of the tensioner. Not sure if I explained correctly.

[clyon51]

All I can can say if you put a new belt on wrong, you are in trouble.... period. Then you have to weigh the cost saving vs doing it wrong and having a professional doing it right the first time. I’m not knocking anyone for trying to do anything themselves, I’m just saying, before you to do, ask for help first.

[saddlesore]

Directed to EVERYONE reading this thread.....
Grab your cell phone or camera and take a few pic's of the serpentine belt (actually all of your belts) on your engine..
That way IF you have to change out the belt(s) you have a reference point (pic's) to guide you on correct installation(s)...

[Monacoach]

Originally Posted by clyon51

All I can can say if you put a new belt on wrong, you are in trouble.... period. Then you have to weigh the cost saving vs doing it wrong and having a professional doing it right the first time. I’m not knocking anyone for trying to do anything themselves, I’m just saying, before you to do, ask for help first.

Heres what happened. The surpentine belt broke while on our way home from a trip. I called and gave a mobile mechanic the wrong part number and of course he showed up with a belt that was to short. ( not his fault) ( I blame my manual) ( ok it was my fault)
Anyways he installed the belt but Informed me that the tensioner seemed to be weak.It got me home ( 200 miles) I researched the proper belt routing and noticed that he routed it incorrectly. I re routed it to the correct configuration but it seemed way to tight.
3000 miles later it breaks again. I get towed to a garage and I give that mechanic the same wrong part number. He gets the belt trys to install it and then tells me it is way to small. We notice the manual mistake and get a new part number by reference of the engine vin number. He says now that I have the proper size belt i should be fine.

[Mr_D]

I changed my belts at 25,000 miles and saved the old ones as spares. They were still stored at 47,000 when we traded the rig off. They will last many miles if everything is set right and installed correctly.

[Tony Lee]

Originally Posted by clyon51

All I can can say if you put a new belt on wrong, you are in trouble.... period. Then you have to weigh the cost saving vs doing it wrong and having a professional doing it right the first time. I’m not knocking anyone for trying to do anything themselves, I’m just saying, before you to do, ask for help first.

OP said " they routed it", not "I routed it" so maybe the experts stuffed it up

[Monacoach]

Originally Posted by Tony Lee

OP said " they routed it", not "I routed it" so maybe the experts stuffed it up

Thanks Tony yes it was a so called expert who installed it incorrectly .
My manual lists the surpentine belt part number and all other parts for the 2008 5.9 cummins engine where as my engine is the 6.7. They changed engines mid year but this was not reflected in my manual or they simply gave me the wrong manual.

So yes it was installed incorrectly probably because it was to small to route the correct way. With help from my brother we re routed the belt properly but had to pry it onto the last pulley. Was able to just get a maybe 1/8 th of an inch of belt onto the pulley then turn the ignition key in short bursts to get the belt fully on. So we drove a couple thousand miles with our 6.7 engine with a surpentine belt sized for a 5.9 engine before it ripped apart.
Now we have the proper sized belt routed properly. Hopefully that is all that is needed.

[RKins]

Did you buy a spare and put it in the coach in a cool dark place?

[Monacoach]

Originally Posted by RKins

Did you buy a spare and put it in the coach in a cool dark place?

Checked with cummins and supposedly my belt is no where to be found in Canada so I will be ordering one from the USA.

[Monacoach]

just a follow-up to this old thread..

My latest serpentine belt didnt last long. 3 hours of driving and 5 months sitting.
I started the coach today and the belt was again broken. I cant turn the alternator pulley by hand so I presume its seized and the reason for the serpentine belt failures.

I assume the alternator pulley should turn freely by hand?

[Spk64]

Originally Posted by Monacoach

just a follow-up to this old thread..

My latest serpentine belt didnt last long. 3 hours of driving and 5 months sitting.
I started the coach today and the belt was again broken. I cant turn the alternator pulley by hand so I presume its seized and the reason for the serpentine belt failures.

I assume the alternator pulley should turn freely by hand?

You are correct should turn free. I would recommend putting a new tensioner on also.