I noticed on my Porsche 996 that the coolant level was about a half inch below the minimum mark on the overflow tank. So I decided to top it off well after taking her for a drive a noticed coolant coming out of my overflow hose. It eventually stopped and settled back down to the same mark it started at.
This has happened over and over again on three separate occasions. Here is what I have done so far:

1) Replaced the Cap (Mine ended in 02 so I put a 04 on)

2) "Attempted" to replace the coolant overflow tank.. Mad points to any of you who were able to get that sucker out of there. Mind you I saw no leaks from the tank itself - verified that each time it was coming out of the hose.

3) Verified that no leaks were present in the oil or plugs

I plan on flushing the entire system this weekend and maybe there is an air pocket somewhere. It doesn't make sense the car has never showed any signs of overheating (keep in mind we haven't have a day above 75 yet) and it always goes back to the half inch below minimum mark. Once it is there the coolant never overflows or drops below this mark.

Could this be the new "min" mark and that is why it always settles out to that mark? Anyone else experience this? I am not ready to throw in the towel and take it to the dealership yet! Thank you for everyone help

 

Mine's the same. Fill it up to the "full" mark and it blows it back out the overflow so I leave it where it is and just make sure it doesn't go below the min mark. Temp still settles between the 8 and the 0.

 

The correct answer is - if it is overflowing you filled it too much.

 

The fill is correct, they tend to run just below the min line. As mentioned, if it's overflowing you have too much.

 

+1 Same here.

 

Not rocket science but plain liquid expansion and retraction science. Heated liquid expands. Cooling liquid retracts. Happens to most liquids. There is a saying. Doing the same thing over and over again and expecting a different result is insanity. Nothing wrong with your system. If the coolant disappears from the coolant tank, that's the time to be worried. Your system is not over heating. Don't worry about it. But keep your eye on the cold level before your start the car. Is the coolant tank the original to the car?

 

Same for me.

FWIW, the blue "04" cap actually was an improvement ... my old black "01" cap leaked.