s4alex

Maybe, not sure. Are you first owner or do you know complete history of car?

I would try what BigSmoke satated, about taking a picture of the back of the coolant tank (when cool) to see if you spot any weeping or leakins in the nipple section.

If the entire coolant tank looks clean, then see if you can try and follow the lines and spot any leaks. If you can try and get a good view of the pump try looking there.

If all else fails, take it to your dealer or fav indy.

DB's997

I am the third owner, she had 44,500 miles on her when I purchased early this month, April 2015. The tank looks extremely clean, of course Momentum Porsche detailed her before I took possession. I expect the engine bay was detailed as well. The Independent that did the PPI did not see a leak, and they noticed the low level. I will be looking very closely now for any signs of leakage. Crap, I didn't want to have to deal with something like this on my new to me 997. My old 996 was in great shape and I had just had the 60K service done.

DB's997

The new cap seals so much better, problem solved. The photo is after the cap has been off for more than 24 hours. The permanent grooves baked into the old cap looks to have prevented a good tight seal, allowing a slow steady pressure release along with fluid?

DC911S

That's what my original cap looked like too at 45k miles. Not much of a seal

Ericson38

Glad to hear you found your leak. We just bought the same car, seal grey, cab AWD, with Carrera S wheels, 6 speed, and in our case, it was the vent line coming from the left radiator.

DB's997

New 2010 Carrera S acquired two weeks ago. I decided to check the cap, big mistake! Old cap had not been leaking, but threaded on very tight. It started leaking as soon as I re-installed it.
The old groves in cap were petrified, unable to get a good seal now. New cap to be delivered tomorrow from Pelican. I should have waited for the new cap before checking out the old one.

malexgcab

I was having the same problem recently. I had a cracked coolant reservoir that was replaced by an indy shop last year. I noticed recently the coolant level was low. I added more and then replaced the cap.

So far the coolant level has not dipped lower.

DB's997

I just received my new cap from Pelican. Put her on hand tight, then a few twists with the big wrench.
Test drive time, looking for integrity in my 3 week old 2010 S. Three miles I pull over and check, I see pink fluid around the cap.
I am unable to budge by hand any tighter. So I drive home thinking I just need a few more big wrench turns and all will be OK.
When I get home I discovered the big wrench turned very easy! CRAP, the cap was completely loose, a trail of fluid leading up
the driveway. I thought I knew how to install the cap, but obviously not. I am thinking the cap got hot and expanded, then spun off?
I turned the crap out of the cap when hot to tighten, hoping that because it was hot, it would seal better.
Anyone know what I am doing wrong here?
( Genuine Porsche part )

DC911S

You broke the threads. No need to use a big wrench. Just hand tighten to snug. Go look at the cap and the threads on the resivior.