Disappearing coolant leak?

[Starter986]

I'm guessing it burped... maybe some air in the system, or too much coolant.

We're you running it hot and hard before you shut it off/down? I believe the recommendation is to, after running the engine hard, is to let it idle for a couple of minutes in the driveway... then shut 'er down.

Wiser minds?

[Rob175]

I suppose....but IF it "burped" or it was overfilled I would assume it would flow out of the overflow tube (IF there is such a tube) and not deposit a little bit in the trunk.
As I wrote it just seems too coincidental to the water pump replacement 10 days earlier.

I guess I'll remove the trunk carpet and sub-floor after I drive it next and inspect it again.

[blue62]

Originally Posted by Rob175

I suppose....but IF it "burped" or it was overfilled I would assume it would flow out of the overflow tube (IF there is such a tube) and not deposit a little bit in the trunk.
As I wrote it just seems too coincidental to the water pump replacement 10 days earlier.

I guess I'll remove the trunk carpet and sub-floor after I drive it next and inspect it again.

If it was me I would leave the carpet and sub floor out for a number of drives and check it each time I drove it. Then I would know for sure. Also there is a wire loop on top the coolant tank it is a bleeder valve there is a gasket under it which can go bad and cause some coolant weeping. Or the service tech could have just spilled a little around the top of the tank and it found its way to the ground.

[Rob175]

Thanks for the suggestion.....I removed the carpet, drove it all day, stopping several times to check the trunk. It took about 3 trunk checks before the leak once again showed up. I drove it to my "indy" Porsche guys and sure enough the bottom far corner of the tank (seen with an inspection mirror) has what looks like stress cracks (btw, the plastic tank is very dark brownish/yellow). These cracks appear to be dripping coolant once the coolant gets hot and the system gets pressurized. It holds the coolant for awhile than just "spits" it out all at once, then pressure goes down a bit, the coolant stops leaking from the cracks, until the pressure builds up once again and it "spits" again.....and the process just keeps repeating. That's why it sometimes appears that the leak is gone in between clean-ups.

So.....it goes to the shop tomorrow for a "genuine" Porsche coolant tank replacement. Between the new water pump replacement 2 weeks ago and a coolant tank replacement this week i'm "tapped out". My 1998 Boxster has never cost me as much as it has in the last few weeks. Hopefully it won't need anything else for this driving season. I can't really complain because the car has barely cost me anything over the 15 years that I've owned it, except for the usual maintenance, tires, brakes, oil changes, battery, etc etc.

Before anyone suggests I perform the work myself, don't bother. I have no way to lift the car, nobody to assist and limited space and expertise to attack it so I "pay the piper"....LOL