Hi, newbie here looking to buy mb vito 108 van its a 99 t and has 78,000 on the clock, the guy im buying says the only problem with it is that its started losing water after about 100 miles, engine not overheating just the water warning light coming on. Spoke to a mechanic who warned me to stay clear as he suspects head gasket problem although he is no merc specialist, could there be a more simple explanation and what should i be looking for when i go to look, thanks for any advice.