What did I do wrong here? There is a thin layer of rubber on pulley and there is a very slight hesitation. Other than that runs perfect with no lights.
There was no sticker. The more research I do I think I’m having trouble with the temp set on the tension pullyIs that a new idler pulley?
If so there is often a sticker on the roller, did you remove any stickers?
In any case don't think there is much that can be wrong. If concerned just buff the residue off the pulley best you can with scotchbrite, engine off of course. You may have to crank it over by hand to get to all the surfaces.