I have a 1999 Jeep Cherokee Sport 4.0. Recently, my serpentine belt snapped off. At this point I figured the belt was old and time to replace anyway, so I went ahead and put a new one on. A day later, it snapped again. The idler pulley didn't seem like it was bad, but I replaced it just in case when I put another new belt on.

Now, my problem is that somewhere along the way, there is friction on my belt, causing it to burn and snap, but I cannot figure out why. The pulleys all seem fine, the tensioner seems fine, and the alignment of all the pulleys seems fine as well.

The only opinion I've been able to get is that the fan/water pump pulley has gone bad/is frozen. So I guess my question is, can this actually happen with the fan pulley? I didn't think it had bearings like the other pulleys, so I'm wondering how it could be "bad."

Literally the only place I can get another fan pulley is on eBay or in a junk yard, so I really need to know if this is the actual problem before I go through trying to get a replacement.

Any advice, tips, help, thoughts as to what the problem might be is much appreciated.

Also, I don't know if this would matter, but just in case, the entire cooling system (water pump, thermostat, radiator) was replaced brand new just over a year ago.

Thanks!

 

If I recall correctly, I don't think fan pulley actually has a bearing. It bolts to the water pump which contains your bearing. If the water pump bearing were seized, you would be overheating as the pump would not be rotating. Plus you said you recently replaced it.

I would remove the belt, and see what pulleys spin freely. The idler, water pump and power steering pulleys should turn pretty easy when the belt is removed.

The main place I would hone in on and check is the A/C compressor clutch. The clutch might be seized and not turning at all or on the verge of becoming seized.

 

 

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It does run hot, but I figured that's because the belt isn't on to turn the fan and start cooling the engine. I checked all the pulleys and they all seemed to spin fine, not too loose, not too tight or frozen. I will check again when I get home from work today, but I'm fairly certain that with the belt ON, the fab will not rotate.

I don't think it's the compressor, only because the part that the belt fits on is grooved. It seems that the belt is being burnt to point of snapping on its smooth, non grooved side. I don't know if that matters, but it seems logical. However, I will check it out in the process. Thank you.

 

Take a serious look at your harmonic balancer. It is a two piece design with rubber between them. When it starts to go bad, it will separate and can cause belt squeal/breakage. It can be hard to see. I'm on the app or I would post a photo. Use a good straight edge to check it. Search harmonic balancer on here and you can see some photos. I had this problem, luckily I have a parts XJ so mine was a free replacement.

 

Define "seem". How were all the rotating components which are driven by the serpentine belt, checked?