Coolant tank cap
 

Sorry for my ignorance I know that these cars have an issue with the coolant tank cap what I am unclear about is does the coolant leak out directly from the cap or is it overflowing through the overflow tube because the cap is not keeping the system air tight?

Yes.......

Yes it leaks directly from under the cap or yes the cap let's air in causing boiling and the coolants escapes from overflow?

Yes.......

- yes bad cap allows air in (de-pressurizing system and greatly reducing boiling point of coolant...)
- yes coolant leaks directly from under cap (mostly steam vapor - white crusty residue is sign...)
- yes coolant escapes from relief valve on boil over via overflow aka Boxster will "pee" in front of right rear wheel...

best thing to do with an old cap is to leave it alone until you get the new one. Each time you take off an old cap it holds less pressure and opens the door to problems. Replace the cap every two years.
One of our resident mechanics says it must hold at least 18 PSIG or he tosses them.

Thanks for the info I am assuming you buy your caps directly from Porsche or are aftermarket caps ok?

Porsche replaced the cap with a newer version. I got htat directly from suncoast. Given the issue with faulty caps, I'd just go with the newer porsche cap.

While youre at it, take a look at your gas cap. If the rubber gasket looks cracked, get yourself a new one of those before you start getting a CEL.

If you're still on that original factory cap you might want to have the coolant flushed with the factory pink coolant and have the updated cap on hand. The 101 Projects for Your Porsche Boxster book recommends a flush every couple of years, probably great for DIY'er who can vac fill.
In the meantime it's useful to have a small LED flashlight in the armrest storage that you can use to light up the coolant tank from behind so you can quickly see the coolant level. Sometimes it's hard to tell if its too dark or bright out. If the coolant is below the hash mark on the tank you may have a crack/leak somewhere. Once its vac-filled it should not fluctuate unless there is a leak or air has gotten in. I got in the habit of checking this with the flashlight before I got in for a drive around the time my water pump started sounding funny. Sure enough I missed my appointment to have it swapped out due to work, and it let go the day before my new appointment on the drive home... Murphy's law.