Located this on Phil's site. I guess I need a pulley like the one in the picture on the left.
We have a workshop by the barn where I store the CMP. There is a hydraulic press so getting the pulley off should be possible. As long as I can get a hold of the required bits I'll get it sorted. No parts came with the vehicle.
Seeing how big the pulley should be I'm not surprised the cooling systems isn't efficient. It must be making bubbles rather than moving water around.