Fan belt AGAIN!

Asking on behalf of my daughter, who some may have met on the Jimny meet. ( red hard top jobbie)
Anyway her fanbelt snapped again 3rd or 4 th in a year. The crank pulley has been checked by the local garage , when they fitted a new water pump. But can you diagnose the fault of bonding failure when cold and stationary in fairness.?
This morning ...the first deep frost , it squealed a bit but soon stopped , went to the stables and the usual smell , signs ...yep no coolant and a snapped belt.
Question which is the more likely cause , alternator bearings or crankshaft pulley. In ideal world both , the water pump is new so shouldn't be that,
It's a 2004 hard top so M13 engine no aircon .
She phoned hoping to just borrow our cabrio ....but as fate would decree our brake pipe are gash as per another thread.....

Ps I have read some other threads on here but no conclusions it seems .

With the engine running, look at the pulley/belt. Is there any wobble

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I’ve had two snap on me, after fitting the second replacement I checked and adjusted tension.

I get squealing sometimes when I first start, I avoid using the blower and heated rear window and any lights and let the car idle for a couple of minutes to replenish the battery before driving off.

I know this is more about treating symptoms than a cure, but I can’t find any faults.


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Only a thought,but have you checked the 'V' on the water pump pulley which you say has recently been changed.
If any of the 'V's' are different, alternator-water pump etc are the wrong profile it will cause excessive wear on the belt under tension.

i had this kind of thing happen to me a few year ago i was stumped all pullies was ok and the water pump was fine , the problem turned out to be the altornator bearing but the bit was when you spun the pulley it spun well what was happening was after a while running it would tighten up to almost siezin up , i changed the altornator and all was well i went thru a few belts before i got it , best way is to be ready to spin the altornator pully after a trip when everyhting is hot

Which engine is it? If its the m13 it is not always obvious when inspecting the crankshaft pulley that it is delaminating. My daughters car ran two belts and I replaced the pulley and no further problems. There looked to be nothing wrong with the pulley! Ensure you put the correct length belts on. The numbers relate to the length.