Radiator Overflow Tank Overflowing !
 

S6 FD 13BREW: I had been loosing coolant slowly for a while and I have simply been topping it up each day. I put this down to a small leak in the Air Separator Tank which had been repaired previously but was due to be replaced with a stainless unit. The amounts of water were getting larger each time.

I finally came around to doing this and noticed something bizzare...Whilst the AST was leaking a few drops I noticed for the first time that my overflow tank for the radiator was also overflowing onto the ground. I have never noticed this before. Only it was not a few drops but a fairly large puddle.

I fear something may have gone horribly wrong as the only thing that could force water out of the overflow tank is if the cooling system was under extreme pressure. Pressure from the engine that is - where else?

Has anyone seen or heard of this before? Help!

yup....most likely coolant seals, but give the whole coolant system a good check and maybe you'll be lucky.
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that happens to my fd, on hot days after i stop the car, and after my turbo timer shuts off (and I did the cooling fan mod), coolant will spill onto the ground. After it stopped overflowing, the level is always fine, and I have brought it into the dealer, actually two separate mazda dealers and they have given it a thorough look through the cooling system, and found nothing wrong. Idk if yours is the same case though.

something like that happened to my FC. it was the radiator cap though, the valve was bad on it and it would keep building pressure till it forced most of the coolant into the overflow tank. course my coolant buzzer came on and that when i saw a 98 percent full overflow tank, had it checked and 12 bux later no more problem. anyway, good luck hope your problem is 12 bux also