I bought my mk3 gti 2.0 last october. Ever since i bought it the engine has never ran hot, the temp gauge has always stayed really low, or at best after the car has been running for a while and sitting idle maybe at a 1/4 of the way up, and my heat has barely worked, maybe running warm a little bit when the car showed 1/4 of the way on the gauge.
I've been thinking that it is probably a thermostat problem, I purchased a tstat and some coolant and following Dan's DIY tstat change I put the new thermostat into the engine block then put the oring in, then the thermostat housing over it. It seems like I finally have filled the coolant up and the car warms up like normal it seems like, but the gauge keeps going up to 230f and thats when i turn the engine off. The top radiator hose gets hot, the bottom radiator hose and radiator are cold.
I dont think it could be the water pump because I didnt have any issues before with overheating, but when I take the hose off of the top of the coolant bottle and rev the car up nothing comes out. I saw in another forum of someone recomending sucking on the end of the hose to pull coolant through? Does that make sense? Could the thermostat i put in be bad? Is it possible to put the thermostat or o-ring in the wrong even if tstat is facing the right direction? Please any help would be appreciated. thanks