I have a 99 xc70, I had a problem with the cooling system a few months ago. After driving it for an hour or so, it would boil over after turning it off. the temp gauge would show the temp was in the normal range (dead center of the gauge). I then blew the engine up on the highway...ran out of coolant. So I replaced the engine and the same problem is still there. I loose about a quart of coolant everytime I turn it off after driving a hour or so. Short trips of 20 mile or less there isnt a problem. I check the cooling fan and it is working. I watched the gauge when I turned it off and there is no temp spike. It appears it is only leaking from the coolant tank/cap.
Has anyone seen this before?