I have a 2004 Toyota Tacoma. Recently in cold weather there is a high-pitched whine/squeal coming from the engine area. I have ruled out belts with belt dressing spray, and I think I've narrowed it down to the water (coolant?) pump because if I apply a small amount of WD40 on the shaft behind the pulley (is that the term for the wheel the belt turns?) it will stop squealing until the next commute.
My best guess is that the pump bearings are going and it should be replaced. If this is a correct diagnosis, should I replace the unit entirely or is there another fix (e.g. new bearings)? Since I don't know enough about working on engines, I will likely have a shop do the work. That said, should I address this immediately, or should I wait until the belt replacement is due (in another year perhaps) to save on labor costs?