A week ago I got the "check coolant level" alert which prompted me to pull off the road at 6am on a Saturday on my way to a cars and coffee. The temp gauge didn't move from its typical 185* mark. Turned off the car, and noticed that sure, it's below the "min" line and chalked it up to possibly being a vapor leak from my old .01 blue cap since I see some flaky white crud around the cap. I managed to put some distilled water in to bring the level up to the "max" line. So far so good, no more alerts.
The next day going to work, quick 20 min fwy drive, I park on a slight incline nose up. I come out to the car at lunch and notice a small coolant drip (maybe a teaspoon worth) of coolant on the ground. Dripping from the heat shield near the rear drivers side turbo. I chalk it up to possibly slight overfill and parking on that slight incline as to the reason it dripped.
Up until this past Saturday, I didn't notice any more drips whenever I parked the car after driving to and from work, sometimes a good 1-1/2 hours of stop and go LA traffic.
This past Saturday I had to drive about 40 miles to work. No drips or leaks after the drive to, but after driving home (more spirited of a drive home, probably shaved a good 15 minutes off coming home) I park in beginning of my driveway (very slight incline) nose up. When I came back outside to walk the dog (a good 30 minutes after I got home) there was now a faster leak happening ( about 1/2 cup worth) on the ground. Dripping from the same place as before with a tad dripping from the heat shield above the exhaust tip.
So thinking the tank has formed a crack. Supposedly the tank was replaced about 3 years ago via the PO. No records or receipts so who knows if it's true. The tank definitely doesn't look 14 years old. It's relatively white in color.
Today, to try and find out where this leak is originating from, I added about 2 cups of distilled water to bring the level back up to just under the "max" line. I removed the rear bumper inner fender liner, heat shields above the exhaust and turbo. Put the inner cooler back on, start the car and bring up to temp. Turn off the car and no leaks or drips?? So I can't see where it could possibly be coming from. I did notice some white/ orange residue on the rubber overflow hose tip.
Should I still chalk it up to being an overflow issue. Owned the car for almost 2 years now. And only started having this drip/leak after I added the distilled water.

 

***update*** so I let the car warm up with the A/C on full blast for about 15 minutes. Low and behold it started leaking 1/4 cup worth of coolant. Pulled the inter cooler back off, and by using a small mirror and flashlight, I can see residue build up on th bottom of the tank. So I'll take that sign as a cracked tank. Ordering parts now

 

i/c are air to air and have no coolant flowing thru them. look at the reservoir tank for cracks and yellowing. its likely leaking and running down the i/c

 

coolant tanks are very common. Do you have a way of pressurizing the tank?

 

Yeah, a year ago when I took the whole rear apart to change the spark plugs/ coils I realized it was a non coolant flowing I/c system. I don't know why, but I did put i/c back on before starting the car, just to take it back off again to see if I could find the leak source. I just figured if there was a cracked tank it would leak all day everyday until it was empty. And couldnt figure out why it coincidently happened after I topped off with D-water.
I have to say I do enjoy learning more about these cars with these little repairs. (CV boots, micro switches, coolant leaks.......)

 

I don't have a Uview 55000 but I may try making a tester using the old blue cap and an extra gauge I have.

 

its not worth the effort. if the tank has any signs of yellowing replace it. not very expensive and ot hard to replace

 

No need to go to that much trouble.

You can run a hot pressure test easy enough. Turn off the A/C and drive the car around the neighborhood at slow speeds in say 2nd car -- at around 25mph or whatever the speed limit is -- until the engine/drive train is fully up to temperature.

At home then you can raise RPMs to say 1K and hold until you detect the radiator fans come on. (You might need a helper to signal you the fans are on.)

Let the engine idle a bit then shut it off. You want to shut off the engine before the fans remove the heat that has been built up from the "fast" idle.

Once the engine is off and the coolant no longer circulates the heat load will raise coolant temperature and pressure and if there's a leak you will know it by the coolant hitting the ground.

Be careful. When I did this a few years ago my Boxster's coolant tank let go with a gush of hot coolant.

The leak may be in one or more radiators -- I had all 3 leaking back in Jan. of 2015 -- so sniff around the front of the car. If you smell anti-freeze the odds there is a radiator leak, or 2 or even 3...

The coolant cap can leak, too. I had to replace both the one on my Boxster and my Turbo. The newer cap has a part # ending in "02" or "04". Even if the cap part # is one those part numbers, it can still be bad.

Make a tent of alum. foil and place over the cap/top of the tank. After a few minutes remove the tent and if any water has condensed on its bottom surface the cap or the tank or something in that vicinity is leaking coolant.

 

r&r of the expansion tank is at this point a highly recommended suggestion. esp if yellow/cracked and you see white dried coolant residue on it or on/near the motor mounts.. its not a rad leak? if its the tank. common. replace the blue cap too.

 

Yeah, parts were ordered (tank, blue cap, manifold gasket) all currently sitting in my living room waiting for a day off to r&r. I also just ordered a Uview 550000. Seems it would make life easy come refilling the coolant system