- What type/brand of V-belt? Top cog types (with the notches on the outside of the belt) tend to be problems. Go to NAPA and get their Premium belts.
- Do you have the stock crank pulley on the engine? An oversized crank pulley would spin things faster.
- Is the adjustment on the PS belt at the end of its adjustment range when you put on a new belt? How much belt wiggle is there when you tighten the PS belt? You should be able to wiggle the belt in and out the belt no more than + or - 1/4" when it is properly tensioned.
BTW, the pumps may spin free by hands but that is not a 100% guarantee of them spinning freely at running RPM's. Wiggle the water pump pulley side-to-side and if there is any sideways slop, then the bearing is going. Sitting for that long, pump bearings may be suspect.
