I am going through coolant like crazy on my 90 wagon. About a gallon every 100 miles. There is the faint smell of coolant turned to steam under the hood, but no visible signs of water/leaks. I just left Wolfgang the local Volvo guy, who put a pressure device on the fill tank. The system held pressure of 100lbs for 10 mins. with the engine off then slowly lost pressure to 80 lbs. with the engine on. There is no noticeable steam or the smell of steam coming from the exhaust and the oil looks good...no white sludge. With this much loss I was thinking blown head gasket but with nothing coming out of the tailpipe both Wolf and I are stumped. Any thoughts?