I had one of the first Koolance systems, the one with the big aluminum resevoir / heatsink on the bottom of the case but without the watercooled power supply.
The pump in the resevoir was a cheap fountain pump. I had two of them die on me. The first (original) pump had a burned trough coil. It was completely dead. The second pump had its impeller catch something in the housing and stopped turning. My guess is that the resistance of the narrow water hoses is too much for these pumps to perform properly.
Also the power supply died. The only part of this case that is of some quality is the resevoir / heatsink. Totally useless though because a regular heatercore is much better / lighter / smaller. I will never buy a Koolance product again. Wasted $350 on that piece of crap.