Just got back from the dealer for second trip to diagnose coolant loss. Same answer as last time. " No problem " it's normal for these cars use coolant. And no answer to where the coolant may be going.

Issue is that tank losses coolant over a period of time,say 3 weeks, and levels off about 1/2" below min mark when hot. No warning lights, temp never above 175. Some evidence of leak at the cap but minimal. Nothing unusual coming out of the tail pipes.

Have heard these cars can leak at the water pump and the "Y" pipe under the intake manifold. Any other suggestions or possible issues would be beneficial. Don't believe the car is in any danger of overheating and have it on record twice on service tickets.

 

Sorry but that as an absolute crock of $hit. No engine should ever loose coolant for any reason. They are sealed systems and the only place for coolant to "move" is into the overflow tank area between cold and heat cycles.

But bottom line you should never have to add, unless for some reason you have a faulty cap and some is spitting out when the engine warms up.

 

The car should not use coolant. I had the low coolant level warning go off once. It turned out to be a radiator hose clamp that was leaking a little, only while the engine was running. Clamp was replaced.

 

After two 997.1S cars , one Turbo , and one 997.2S --I have NEVER added coolant .

 

Check for coolant leak at expansion tank cap.

 

You mentioned the level while the coolant is hot but what is the level after the coolant is allowed to cool over night?

To insure no leaks inject an ultraviolet dye and expose it to a black light.
This will provide a thorough inspection and if any coolant is leaking it will pop out right in front of your eyes making the leak hard to miss.

 

Have checked cap. There was some evidence prior to first trip to dealer. Not wet but some white deposits just under the cap which would indicate it was leaking and drying. Also some just below this area inside engine compartment. Cap was replaced after first visit, tank was pressurized and checked for leaks by dealer and was said to be OK. Second visit was a few weeks after system was topped off and again same issue with no tell tale signs on the parts of the system easily seen.

Will check fitting connections for signs today after the getting the car to normal op temp. Had this issue with the Boxster but it was an obvious tank issue which was replaced under warranty and that fixed it. The issue here is that once the tank gets to specific level it stays at that level. Which would suggest to me a crack in the tank somewhere above the coolant level but dealer pressure check says no.

Don't suppose there is any easy way to check the water pump for a slow leak ?

 

Coolant level seems shows little difference once it gets to a certain level and is not recovering when cold. System was tooped up yesterday at dealer so will check it hot and cold, once weather allows for a test drive, and report back.

Will suggest the dye test to dealer next visit as it sounds like a lift would make for a more thorough inspection. Sure sounds like a good excuse to buy that lift I'm been looking at.

 

I like your thinking. I have had Eagle Equip SS7000 for about 5yrs now and not only is it excellent for items like you suggest, but, also great for stacking cars. (My ceiling is only 9'10" high, but easilly can stack my C2S above my wifes Z3.......so I can keep the motorcycles on the other side of the garage!).

 

The coolant reservoir is known to crack and leak out the tail pipe. get a good flash light and look at the bottom of the res. by the level sensor or on the rear frame rail under the res. To get a good look the intake tube from the lid to the air box needs to be removed.

 

So...what was the resolution on this? Where was the coolant going? I'd be suspicious of it being devoured by a system. Was there a leak?