Coolant Expansion Leak - OK to Drive?
 

Right after I gave the 986 to a family member to drive 800 miles home, he told me the coolant temp light was blinking.

After diagnosing it, it seems like there is a small crack on the seams between the black and clear plastic part of the coolant expansion tank.

If I keep the coolant level below the Low line, nothing leaks out, but when I refill it to the Full mark, coolant would leak out of the crack and then settle at below the Low mark after the car cools down completely.

He wants to just drive it home and take his time to fix it. I think he should be fine since it's essentially like driving with the coolant bleeder valve open right? Or am I completely wrong?

Absolutely not! The tank will not hold pressure with a crack. There needs to be pressure in the system to prevent localized hot spots in the water jackets that will boil forming vapor and preventing proper heat transfer especially along cylinder jackets and heads.

Oh and do not use an aftermarket to replace, that is a common problem area even with the OEM German tank.

And to answer about the bleeder. The bleeder does not vent to atmosphere. It is a high point bleed from the front radiators and the oil cooler to eliminate air in the system.

Sounds like we're gonna have to tackle it before he leaves. Thanks!

If he doeasn't have to go home right away and can wait 24 hours, and the crack is within easy reach, you may want to try JB Weld for the ride home. It does take about 24 hours to cure. I know some pusirsts on here will poo-poo my suggestion, but I've used it to make some "temporary" repairs on a few radiators which ended up outlasting the cars themselves. I even used it once on my 94 Ford Escort with a leaking tranny pump cover with great success.

Of course there are risks, and the safest is to replace it as 911MMonty suggested, but if you're in a bind and can't do it right away it may be worth trying.

Good luck!

It isn't that difficult of a job to do. Could be done in a couple of hours, 4 at the most just depends on the tools you have. Some have even used a dremel to cut out the old one to make it easier to get out.

It's a PITA do it yourself job....Dremel or no Dremel. I took mine to my Porsche indy. Genuine Porsche tank, hoses, clamps, coolant, and all labor was about $1,100......23 year old Boxster, so it's to be expected.

I agree. It was a BIG PITA when I did it. Mine was on the jack for 2 days. I was about to call my LPS (Local Porsche Shop) for a tow but gave one last try... then I made the break through. It aged me. I am not sure if I can, or want to, do it again.

I read enough of those stories, I paid to have mine replaced :D

They say smart people learn from other people's mistake.
Me? Not so smart. :D

Ha! I'm lucky if I learn from my own mistakes! :D

+1 on comments relating to replacement. My PO installed an aftermarket tank and I had to replace it. I used a genuine from Pelican, and it is a PITA bc of the piping thru the bulkhead. I asked a well qualified friend to look at some articles and he charged me $250 plus a extension hose clamp pliers (you need this is you're DIY'ing).
We replaced the level sensor at the same time, as you need to do it with the tank out.

We feel stupid but lucky. It ended up being the cap... We put on the "04" updated cap and no more hissing sound and no coolant loss.

If you have any doubts before the trip get the system pressure tested.;)
If there are any issues a pressure test will tell you.
It is a very simple test.