I was out with my wife in our 2003 Boxster with 79,250 miles yesterday driving to three locations each about 10 miles apart. We were late to the first appointment and we took a back way with winding roads. It was a beautiful day and we made good time. It was the second nice drive on windy roads for me of the day. The car was running great.
When we pulled up to the last location my wife notice a bunch of fluid pooling at the curb. Sure enough, coolant was boiling over and running down the overflow tube. I popped the engine cover and couldn't see anything wrong. 20 minutes later there was still some coolant in the expansion tank and I drove with the coolant light blinking to a Seven Eleven 3 blocks away and bought a 24 pack of half liter spring water bottles. I went through a little less than 4 liters and then took an easy way home of roughly 10 miles. With all the covering off the engine certainly sounded different but it didn't sound troubling. It did seem like the Tiptronic was keeping the car in lower gears a bunch, but that might have just been that I'm not used to driving it like an old lady with triple cataracts I stopped half way home and there was plenty of diluted coolant left even as I could see a trickle coming out by the wheel. Not surprisingly, roughly the same amount of water made it onto the driveway within an hour after we parked at my house. Not once did the water temperature gauge seem high.
When I started surfing the boards, I learned that my version .01 coolant cap could be the culprit and should be replaced. I have also read up on this possibly being a head gasket failure which would be much worse. I did pull the oil cap and found more than a few drops on the underside. I have attached a photo but that's after I cleaned up roughly half of the moisture with a paper towel to see if it was colored (it was brownish, maybe a little yellow). I then looked at the dipstick and the Mobil 1 seemed to be a bit watery and maybe a tiny smidge yellow but I might be paranoid at this point. That being said, it didn't seem like a milkshake. Another point to make is that I bought the car used in 2008 with 28,500 miles from a Buick dealership. They had flushed the coolant and replaced it with standard yellow antifreeze which hasn't been a problem (until now?).
The worst part is that I live in Austin and work in San Antonio. We have three cars but my wife is driving the 2000 Suburban b/c her 2007 MB E320 Bluetec is leaking enough oil that it drips on the engine and creates some awful smell and a little smoke. Not good. It looks like I'll be spending $200 to rent a car tomorrow through Thursday unless I get some confidence that my Porsche can make it the 80 highway miles without risk of damage.
What do you think might be ailing my beautiful, until now trouble-free car? What diagnostic tests can I do myself to see if the head gasket is shot?
Drain some oil from above using my topsider? Open the oil drain plug to let a little out?
Cinch down the coolant cap harder?
Drive driving it again to see how the engine is running? Maybe look for moisture in the exhaust?
Thanks in advance,
Trevor
P.S. I did install a new water pump (no broken vanes) a couple months back after the bearing went. And I installed a low temperature thermostat at the same time.