If the idler pulley bearing has play in it, replace it before it bites you in a bad place.
You do not want that collapsing on the freeway at 70.
Or halfway up a mountain trail.
You should be able to get just the pulley with the bearing installed instead of the whole arm.
If the old one is steel, and the new one is plastic, you can sometimes get the replacement bearing and replace it so as to have a spare if the plastic pulley wears out.
Funny thing, my 89 Ford has plastic a idler pulley.
It wore through the part that the belt rides on in about 15K. I bought a new pulley and bearing, and it lasted about the same length of time.
So, I bought a couple of them, and made me an arm with a socket welded to it for changing them in the field.
Every so often, I could check how deep the plastic was worn and replace the pulley if it was getting close.
One day, it suddenly quit wearing. The pulley looked the same, but there was no wear to speak of when I checked.
After a while it was starting to bug me. Everytime I checked, no measurable wear.
Finally I checked with a Ford guy I knew. He started laughing. It seems on my Ford, the waterpump and fan runs off the back side of the serpentine belt.
Ford was worried that there might not be enough friction on the slick back of the belt to spin the fan and pump, so they specified a soft sticky type backing on the belt.
Then, they discovered that it picked up sand and wore the plastic idler pulley out.
So, they changed the spec to a harder slicker back. When I changed the fan belt, I got the new spec without realizing it and so the pulley quit wearing out.
