mystery squeal '89 W124 (squeak)

[Ironzey]

Hi all,
I have an '89 300E with 150k mi that sqeals all the time now. I first noticed it back in febuary on a warm day, now it's constant. I don't think it's the serpentine belt because I just recently replaced it along with a new tensioner. I am also having some cooling issues wich I suspect is the cooling fan clutch. (the car runs hot, +100, when idleing,or in stop and go traffic for more that a few mins). As far as maintainance goes I don't know what the PO has done, but for the last year I've changed all the fluids.

Thanks.