Throwing belts

How is a Kysor fan clutch adjusted?
I have seen worn pulley grooves cause similar problems.
17 series belts in 22 series grooves can surly do the same thing.
What belt is speced for your truck by the serial number and do you know if it is original?

 

Worn pully grooves would cause slippage and wear the sides of belts causing them to ride lower in the groove.As already mentioned Belts are supposed to ride on sides not at the bottom or small part of V on belt. When the grooves are wore out the belt slips no matter how tight you get them because their riding on the small part of V deep in pully Sounds like the belts You have are too wide or the wrong pitch. If the grooves are worn you can usually see the wear.Were the old belts jumping also? I would double check for proper belt part #

 

Make sure pully are clean.

 

My Detroit has 17 series on the fan pulley.
All my cats are 22 series. I bet you guys someone put wrong belts on his engine.

Worn pulleys dont make belts jump off.

Pretty hard to miss aligin the fan hub and crank pulley unless someone put wrong fan hub on.

 

I think Swaan is right

 

These are 17 series belts on my ddec4.

Belts Run flush with top of pulley.
OP said his belts are higher, so he has the wrong belts.

 

He usually is!
How ever i saw an 8V92 with 20,000 hours on it. Instructions were to keep it serviced, safe, and operating. Spend no extra money on it. It was an off road machine.
The fan hub belts were worn so bad the belts would roll in the pulleys and then fail.
That is unusual so go with Swaan. His belt pics look like our 11 liter three belt Detroit as well.