Problem even porsche engineers have no clue

Anyone has an explaination my coolant in my 987 S mysterious lost on a trip and end up towing back to service center just six month after regular service? 8-4-09 Technician tried the pressure test and there is no leakage found in the system whatsoever. 8-5-09 He then topped up the coolant but all was gone after the test drive. Pressure test again and no leakage. 8-6-09 Coolant topped up and certain amount was lost after 2nd test drive. 8-6-09 No coolant lost after 3rd test drive. 8-7-09 They told me the car is ready to be pickup.

Sorry never heard of that. But I think you should keep a close eye on it!

Did you get any warning lights with this problem?"Low Coolant"? etc.

Yes, what were the original symptoms? If you had to have it towed, I assume that you had some serious indication to begin with. And, how much coolant was added the first and second time? Also, when was the pressure test done - hot or cold? One last point - I assume it was a tech and not an engineer, as you mention in your title?

Yes, as above, was the pressure test done while hot? If not, I would. Is the coolant leaking out on the ground - or going out the exhaust as steam?

My guess...there is a temperature range where the leak occurs. As temp changes, the leak is sealed by expansion of something. Any whitish cloudy stuff under the oil filler cap ? I say head issues. But I am not a tech, let alone an engineer. LOL.

Check under the seats! It has to go somewhere! :hilarious:

take it to an auto mechanic aka grease monkey [not the lube joint] and put a dye in the system

Had the same problem just once. Toped it up and it never did it again, and that was BEFORE track days!

Why dont you take your car somewhere else to check again? I never have such experience with coolant. Let me know if you need better mechanic.

Thx for your interest DaveN007. No whitish cloudy stuff anywhere.

Thx azect. Any recommendation?

May be i should check if porsche deserves its status in the industry. HaHa

Found this on Wiki, however may not apply to our cars... Hong Kong is a subtropical climate with humidity up to around 90% at this time of year. Because the thermal efficiency of internal combustion engines increases with internal temperature the coolant is kept at higher-than-atmospheric pressure to increase its boiling point. A calibrated pressure-relief valve is usually incorporated in the radiator's fill cap . This pressure varies between models, but is typically 9 psi (0.6 bar) - 15 psi (1.0 bar). As the coolant expands with increasing temperature its pressure in the closed system must increase. Ultimately the pressure relief valve opens and excess fluid is dumped into an overflow container. Fluid overflow ceases when the thermostat modulates the rate of cooling to keep the temperature of the coolant at optimum. When the coolant cools and contracts (as conditions change or when the engine is switched off) the fluid is returned to the radiator through additional valving in the cap .

Not sure about the HK reference, but everything else seems to relate to the operation of just about every car on the market today...... Unless you have a leak in the overflow bottle, then everything usually acts normal.

Spider, I had a coolant issue at @ 15,000 miles. "Low Coolant" warning but no temp gauge increase. Fluid from the overflow reservoir would cascade just inboard of the right rear tire. Towed to dealer. Topped off, pressure checked good. I picked the car up and by the time I drove it 5 miles back to work, the warning was back on. I called the service writer back immediately and she told me to return right away. I drove it back as I didn't see any fluid leaking. I told them to keep it until they found something. They ended up finding a crack in the coolant overflow tank and the connection to the tube from the radiator line (this is a common problem on most of the water cooled Porsches as it's all plastic). THey replaced the tank and the offending part of the line. It has been perfect ever since. I did not get a Low Pressure Warning. There are other posts here on Coolant Problems you can review that might help in dealing with your service tech. There's definitely something wrong! Craig

I had something similar. And soon ended up with a new motor.

Re: I had something similar. Unfortunately, the service reps at Porsche dealerships are very much like the person you purchase gas from at your favorite station who will not be able to answer gasoline questions either. Some have completed only a little training and have limited knowledge and are in an entry level job so when in doubt push the issue up the food chain. Some dealerships (and all are private enterprises that may not conform to Porsche standards) reward the service writers based on the amount of jobs finished not the satisfaction of the customer. So insist on what you think is fair.

Your right, the field engineers are as clueless on some things as the shop people. Plus they put you through hell. If there is a worse dealer service dept than Bert Smith Porsche, Id love to know about it. I think they are the worst in the USA. I have front end problems, rear latch issue, left belt squeaks. The car has been out of service 90+ days while I pay for it.

I have friends with BMW 's that won't go to Bert Smith as well.

I don't see it mentioned. Is there evidence of external leakage? If not, is there any coolant in the oil?

Was it extremely hot or cold where your trip was? Did they check all pipes/lines? Good Luck!!:burnout: