along the same question, my 01 jetta gls's temperature guage stays on cold, never moves even after driving for an hour and i am burning antifreeze like a kid drinks coolaid. every 4 or 5 days i have to retop it off because the warning light/sound activates.
top hose, hot, bottom cool/warm, but not hot. i think i might have a few issues here, since the temperature sensor is attached to the top hose which is hot, but it never registers as hot on the guage, could i have a bad temperature sensor?
and with the antifreeze being eaten up i'm hoping its just the thermostat stuck closed.
my main question here is, how can i gain access to the thermostat housing screws? the housing is located behind the alternator, do i have to remove the alternator first?