I had an idler freeze up during a 1 hour idle in 104 degrees heat to keep my dane cool.
That caused the belt to shred. Somehow the steel from the belt found it s way thru the inner cover to the crank where it caused the timing belt to jump which resulted in a half dozen rocker arm failures.
So I would advise folks to change out those idlers on every belt change.
It happened a long way from home. Total cost to get it to my garage was $900.00 including rental car, 300 mile return home etc. not to include TB, etc. I did a new head gasket with ARP studs while I was at it. Personal call. But based on my reading on this forum

Bummer. I wonder if the "somehow" has to do with that one slot behind the fan pulley, where it looks like there is a pocket for a different belt tensioner. There is an opening there where it looks to me like debris could get in to the timing belt area pretty easily. I put a piece of closed cell foam in there when I reinstalled the timing cover.

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George Reiswig
2005 Jeep Liberty CRD
Suncoast, SEGR, lift, InMotion tune, homebrew B100
At 138k, new head & gasket, timing belt, rockers and swearing vocabulary

X2 although I would recommend replacing the serp belt at 50K mile intervals or 6years whichever comes first and inspecting the idlers at that time for leaking grease, replace if leaking. You can elect to routinely replace the idlers including the one on the serp belt tensioner as they are all the same. However, IMHO bearings are funny things as they can last forever or go immediately; that said these are sealed bearings so if not leaking grease they should be ok and they should make loud bad bearing noises before going. If you do replace the bearings an alternative to Mopar is NAPA 36101 (just lose the big washer) or Precision Parts EP101

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs