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(E55 Bobcat) New fan belt tore apart after 20 hours of use.....any ideas as to why?

rdavison39

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Hmmm.....okay. yes, that inside belt (to the left) is the one I just changed. So where do you think is the likely mis-alignment? Alternator, flywheel, fanwheel...I'm not sure how to tell...
 

rdavison39

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Just saw stretch in your note. That is not the one I just replaced. That is a couple hundred hours old
 

rdavison39

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I will order a new pump belt - seems like it needs replacing. In terms of being off a tooth I know the pictures aren't great so I took a closer look. I think the belt is in place. I posted some more pics a bit closer up. If you think they are still off a tooth let me know
 

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Delmer

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Coaldust's red arrow to the AC compressor has two grooves visible, and that front belt shows wear. The wear could be from rubbing the failing back belt, that failure could have thrown the front belt off a groove or two on the compressor. Put it on straight, and it might run fine for many years.

Does this have a solid crank pulley or any kind of harmonic balancer?
 

mks

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I would look at the belt/pulley relationship with a mirror or cellphone picture from below the red arrow upwards to see how the belt and pulley groves line up
 

Delmer

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Yes, the visible grooves in the AC pulley are suspicious, but the real test is alignment. A straight edge is the standard, but just looking at that belt with the exposed grooves looks like the belt is at an angle to the groove, that's a tough viewing angle to judge. Take a picture from each end with a ruler on the recessed pulley to show the alignment, will be close enough. It's not like the alignment is adjustable, just make sure nothing is broken or otherwise messed up and the belt is in the right groove and you should be good.
 

rdavison39

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Ah...okay. I see I've been concentrating on the fan/alternator belt which is the one that snapped and then shredded....i will look more closely at the AC belt to see it is still off a tooth. I'm not sure if it has a harmonic balancer or not. Thanks for drawing my attention to this!
 

rdavison39

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Thanks CDust and Delmer. I was focused so much on the fan belt that I have been replacing that I didn't look closely at the AC belt. I looked this morning and as you guys picked out it was off a tooth. I moved it over and it seems to be on all the teeth now. Thanks for helping me out. Took a before and after picture - hopefully this looks good to everyone!



beltoff3.jpg
 

keif

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Mar 8, 2020
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USA
I'm not sure what's going on but only getting 200hrs out of a belt seems way too short of a lifespan.
 

rdavison39

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Hi Keif - the belt may well have over 200 hours. But that is all I have put on the machine since I purchased the machine so that is why I said 200 hours. I should have clarified that....thx
 

rdavison39

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So an update to this saga. After putting on the 2nd belt and triple checking everything (as per pics above with you guys) I ran the machine for about 15 hours this time and the belt shredded yet again :(. I talked to the Bobcat service techs and they felt something was out of alignment and that I needed a technician to remedy echoing aharts comments. So I bite the bullet and had the machine floated to the local Bobcat dealer for their service technicians to take a look. Gave them the history, showed them the pics I had posted here, etc. They went through all the wheels and alignment of everything looked great. They put the new fan belt on (they called it a stretch belt as ahart mentioned) and ran it for a while. The belt ran a bit hot in their opinion so they took it off. They noticed a bit of rubber residue built up on a couple of the wheels so they cleaned it up with a brush and solution and reinstalled the belt. They said that this residue shouldn't have caused the problem but was the only thing they could really find. The bottom line to me was "we didn't find any smoking gun". That really wasn't what I wanted to hear. They replaced the compressor belt at the same time and I had them do a bunch of other unrelated service since the machine was in the shop.

Anyway - I'll be back at the job site in a couple of weeks once i get the unit floated back and will give the machine another run - and will update thread if I make it past 20 hours....or if I do not

Thx again for all your help
 
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