Don't attempt this yourself if Apple will do all the repairs for free (or may even replace your G5 with a new Mac Pro, as they did with me). While there are now increasing reports that Apple is no longer covering the cost of the repairs or replacing the G5s with new Macs, it's still worth a try.
http://www.xlr8yourmac.com/systems/G5_coolant_leaks.htmlAlso, it should be noted that many liquid cooled G5 owners haven't discovered the leaking until the G5 started to misbehave - usually due to damage to the processor. Given the cost of that component (if you can find it!) and the ongoing safety issues involved (power supplies have caught fire in leaking G5s), if Apple won't replace or repair your G5 it really is time to get a different Mac, not mess around repairing it. Just my opinion, of course. And if you have a working liquid cooled G5, it's important that you check it regularly for leaks. And whatever you do, do NOT buy one of these models used.
