UKPassats

Right this has been a problem for a while now when my father In law owned the car and since doing the head gasket it's been a bit temperamental. It's a 2001 model and got a awx engine with nearly 200k on the clock and it will overheat constantly if the thermostat is in but it seems like that part of the engine were it is located dosnt get hot enough for it to open and It's had a gen Vw fitted which I tested myself before I gave it to him but if you run it without it will be ok somtimes and then other times you can't go more than 2 miles without topping it up with water and there is no sign of a leak. This is how he has explqned it to me but once I've driven it a bit I will understand the problem a bit more myself and see if there is somthing he has missed as I only got it today and for £300 and i really hope somone can help me out before i buy a new engine for it