Hey guys!

Today was the hottest day here in MD since i owned my Porsche and i noticed that the reservoir tank expelled some coolant. I checked the reservoir tube that throws out coolant in case of an overfill and it had a drop of coolant so i assume that's what happened. Its been a good daily for the past 3 months, no complains and no leaks..This is the second time it happened recently but the first time was a couple of drops only. I did top off with water that first time the next morning..

Is this expected behaviour on these cars? I am positive the reservoir is not leaking and i added a UV additive to verify for leaks in the area just to be sure..

 

Keep an eye on your temps. About a quarter inch past 180 degrees when driven hard is about normal. If you can see coolant in the reservoir, I think that's OK. The high to low mark is only about a pint of coolant so I wouldn't be topping it off to the full mark as it will expand when hot and do the same things again. Lifting the pressure relieve and expelling unwanted liquid. You might want to clean some of the crap out from between the condensers and the radiators as a build up there can overheat the system. If you are a DIY man there are good video's on YouTube on how to do that job.

 

Do yourself and your car a favor and buy a new coolant tank cap. Latest one I think ends in P/N 04. I drive in Florida and it has been very hot lately, 90+, coolant temp. running about in the middle of the zero of 180. I never see a loss of coolant or drips from the expansion tank overflow drain pipe even on the hottest days.

 

Thanks guys, will do that today.

 

Topping off only assures a repeat....

 

The system shouldn't expel any coolant. The likely cause of this issue is an old, dried-out coolant tank cap. This is a common issue. Pelican and other Porsche sites carry the updated coolant tank cap. I had to replace the cap on both of my M96-powered cars, as the original (1999 and 2003) vintage caps both crapped out and allowed coolant to escape.

*edit* Dammit, didn't see that Joe posted the same info earlier. Oops.

 

Great to hear there is a solution to this issue. I just ordered the black cap from pelican

 

FWIW, I got one of these last fall from Pelican and it is blue. As another poster pointed out, the P/N for the current iteration of caps ends in 04.

 

Same thing happened to me the first summer I owned my 996. Hasn't happened again after replacing cap with newer model.

 

MAX on the reservoir is for HOT engine with expanded coolant. MIN, or a little above, is for cold engine/coolant.
Refilling to MAX when cold will cause some, 1/2 - 1 cup?, to be expelled when fully warmed up.

 

UPDATE:
So I changed the coolant cap and that did not solve the problem. My next step is to replace the coolant tank but first I want to make sure that its bad.

Whats the maximum PSI that I should add to the cooling system to check for leaks?

 

If you have air in the cooling system, it can cause the car to run hot and/or yack out coolant.

 

19 PSI for 20 minutes then check for leaks.

 

Had the same problem and tried the quick fix of replacing the coolant cap......no luck. The issue was a temperature sensor that controls the rad fans. I can't recall how much the repair was exactly but sub $150 parts and labor.
Owner of EU Autowerks in Toronto (a favourite Rennlist Toronto shop) when I reported the problem said that the first place to look was fan operation if the cap was replaced.

 

Neto,
Are your radiator fans kicking on when the car is hot? (check both sides). Also, when you turn the A/C on, the fans should come on no matter the temp of the coolant.
The radiator fans operate on two different speeds, and the fan resistors that allow the two speed operation often fail causing the fan to cease working.

There are also relays in the relay panel next to the fuse block under the driver's side dash. The relays can go bad and cause one or both speeds to cease working.

If you need more info on this subject, just search the forum as there are several good threads about diagnosis and cure.