pretty sure my idler pulley isn't spinning...but the jeep is running seemingly fine? can i drive like this till this weekend? and would this be a good reason for my drop on MPG in the last month?

 

you can view if your idler pulley is not spinning...

and NO you cannot you will burn thru your belt and depending on the wear strength of the belt it is possible the belt CAN catch fire. I bet it would break first tho.

along with the idler pulley you need to get a new Serp belt

 

this happened to the wifeys tj yesterday.
the belt was mia when i opened the hood. i removed the idler and it was rusted except for one spot, the belt actually ground down the pulley a bit.

off to the parts store tomorrow for a new idler and serp belt.

the weird thing is the bearing still spins, but the pulley was tight against the bracket. so i'm not sure how long the belt was turning down the metal before it let go. it was quite rusted.