thermostat?
 

hello,
Just fired up the ole mk3 gte gettin it ready for summer and noticed that the coolant shot out of the overflow for a few seconds (please dont be a BHG) anyway, i noticed that when the engine got up to temp, the top rad hose caved itself in. and by that i mean, sucked itself tight together. do you think it is the thermostat??? cause thats what im hoping for. or maybe a clog in the cooling lines??? i did a compression test last year before i parked it and every cylinder was above 160psi. so what are your thoughts???