2012 S4 Coolant Issue

[Trackiscrack]

Ok, I have searched the forum and probably missed it among the 2010 water pump threads :)

I have noticed that my low coolant light has been coming on every few weeks, maybe once a month. So, I checked it yesterday morning when it gave me the low coolant message and and it had 3-4 inches in the reservoir (mid way between empty and minimum).

I added coolant to the min mark and went to pick up my kiddos from school. I left the car running for 15 minutes or so while the kids played at the park and when I walked back to the car, I notice coolant in a thin line streaming out from under the car (parked in space slanted nose down, driver front down)

Popped the hood and the whole front under pinning between radiator and engine is wet from left to right. Also wet in front of coolant reservoir but no visible crack. Coolant back to mid way between empty and Min.

Went home. Let car run for over an hour, no leaks, drove to parts store for more coolant, drove home, plenty of WOT, still dry, no low coolant mesage, WTF.....

Woke up this AM, reservoir still at the mid way between empty and Min. Added coolant to Min, drove to airport, popped hood, wet again, level back between empty and Min........

Any thoughts?
What am I missing?

Built NASA AI racecars from the ground up, understand cooling systems, would love your input!

[Sceanzo]

Radiator or water pump leaking

[Trackiscrack]

Sceanzo - Thank you for the response. Please elaborate on why this would only happen at Min or Max capacity but at 1/2 qt low, does not happen. I assume it would be a system pressure threshold issue?

[infinkc]

If its wet by the coolant res, then its not likely the heat exchanger.

I would check the connection of the hose going from the res to the system, i had this guy leaking on mine before. If you have done spark plugs, when you remove the res it make the oring in the hose unhappy.

next guess would be the water pump. Get a flashlight and look more close when it leaks again.

[Dr GP]

Get the car to the dealership as soon as possible. Otherwise you risk being stranded on the side of the road. Happened twice to me. First time my WP took a crap. Symptoms similar to your's. Second time, it was a stone puncture of the IC radiator. Regardles of what the cause, your symptom indicate impending failure. If they have to remove the Supercharger consider having them replace the PCV valve while it is off. Also, T stat if that is not the issue. They both have a history of failing

[Trackiscrack]

WP, T-stat and some metal pipe under the SC leaking when pressured up. Also had the 55K service done. Bad day for my wallet! :)