Washer fluid leak 2013 C300 sport
I noticed a blue/green fluid had leaked from front left side ( under the washer fluid reservoir) , MB service said the reservoir is probably cracked and needs replacement.
Checked Engine coolant reservoir , just to make sure it wasn't the source, it was full, done at service in Jan.
The car is always garaged and not used much and after its last service in Jan , it was mostly unused , but there were a few very cold days( -15F ), maybe garage was at 5F
Anyway I refilled the washer fluid yesterday ( 65 F outside air temp ) and didn't see any leaks, drove it around to get the compartment warmed up , still no visible leak on the floor.
What might have caused this leak ? which I'm not able to repeat now.
My theory the washer fluid reservoir has small cracks that contract sufficiently only in very cold weather, to cause noticeable leaks?
Any one had this issue , any thoughts ?




Coolant does flow through the windshield fluid reservoir to heat it up. Theres also a sensor that goes thru the side of it sealed with a gasket.
With the undertrays I know at least for me its hard to pinpoint leaks.
Didn't know the coolant has a sneak path through the washer fluid system, they are supposed to be good till -20, but I guess MB probably has insured it works at even colder temperatures.
I did check the Coolant reservoir , and it seems its at the full mark. So at this point it's probably not the source.
As for the color of what had leaked and dried up on the garage floor, its a bit subjective. To me it was blue-green.
So far the garage floor has been clean since I refilled the washer fluid.
I did question the MB service person, because before I saw this leak this month, the car was in for a Service B in Jan ( was very cold then ) and during that visit , additionally on their recommendation the Coolant system was flushed, but they obviously don't think this leak had anything to do with the coolant flush procedure, and claim its a washer fluid reservoir leak.




I also heard that if you over service the coolant system, it can expand and dump it out , ( Recall I had gotten the coolant system flush in Jan ),
don't know if that's indeed a fact and where exactly it would dump the excess coolant overboard, and if that's what might have happened here.




