a number of things...this was a reoccurring problem on my car when it was in Hawaii. At first, it was a blown gasket on the bottom of the reservoir tank, they showed me the tank AFTER they had fixed it. The car was fine til a month later when it happened AGAIN. I suspect they did not belch the system properly and they put the same original clamps on the hoses leading from it which were not up to date. They claimed nothing was wrong, and refilled the tank and checked it, all good. No problems til I got to Illinois, and the car was leaking slowly this time, anti freeze. Found out the bozos in Hawaii CUT one of my hoses leading from the tank! Aahhhh, I was needless to say, pissed!
Have you had the cars coolant serviced lately? Is this a recent purchase? If so, head to the dealership/service center and raise hell. If not, my first suspicion would be that you have a bad clamp on your hoses, these should be updated, as the original clamps on some of the older Boxsters were not up to snuff....Or you have a bad hose, or perhaps water pump, tho they tend to make some noise before they go, but not always. Good luck, and let us know how this works out for you
