I've had my car for about 14 months now and have to top off the coolant every few weeks or so. After quite a few runs to the dealer and them running a battery of tests checking the vaccuum/Pressure came up with nothing. Everything is fine, they flushed out the system, there is no vaccuum leak, loss of pressure, leaks anywhere around the engine room or under the car when it's parked somewhere. Nobody can figure it out. I took the car to my friend to do some maintenance work on the car and the car's coolant sensor came on saying to check the coolant (I'm so used to this already. It was about a quarter of an inch under the "min" line, so I topped it off to the top of the shaded area where it tells you the coolant should be, drove the car back home, it was parked up all week and I brought it back to my friend again to have the tires changed (ordered 2 tires last week due to road hazard damage), got into the car this morning and the damn coolant warning came on yet again. I opened up the hood and saw the coolant was again, about a quarter of an inch under the "min" line. I filled it up yet again, but this time a lot more, about half of the reservoir is filled now, let's see what happens this time. I haven't been driving it much (maybe 5x in the last 3 mos) because I've been enjoying the summer and the remaining time I have with my Honda S2000 before that lease it up in 10 days. Then i'll be back to full time use on the GTI. Even when driving it all month/year long I still had this problem, so it definately has nothing to do with it being parked up for days/weeks at a time.
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