i have just done a top end rebuild on my 2wd sapph including arp stud and nut kit and a group a headgasket.its using around a tank of water every time i take it out.no more than a tank.when i blow through the relief valve on the cap i can blow through it no problems with no resctriction,surely this valve only vents a little under high pressure.i think the water is escaping through the cap by evaporating.anybody else experienced this?