Liquid Cooling on Power Mac G5 After Years Of Sitting?

My uncle has a late 2005 Power Mac G5 Quad that hasn't been used in many years (quite possibly over a decade)! From what I've heard, the Quad G5s have much better liquid cooling thats not as prone to leaking but I'm still concerned about whether or not the pump could be seized, or if the coolent is gummed up! And if any coolent has somehow leaked out, would the power supply blow up like what happend on that one Computer Clan video? Should I rebuild the liquid cooling, convert it to air cooling, or just power it up to see how it works?

Any advise would be appreciated!