bubbles in coolant overflow = doom?

[andrew444]

Hello -

 

Over the last few months, I've noticed an antifreeze smell from under the hood of my 98 Forester (AT, 95K) after a hard drive. Last night, I looked in the coolant overflow tank and saw a few bubbles popping up. The temp guage has never risen above the mid point, which is pretty much where it is all the time. The coolant looks clean and green otherwise.

 

Would I be correct in guessing this means my gaskets are gone, or getting ready to go? I will probably unload the car relatively soon, am I taking my chances by driving it around like that, or will it last a bit longer?

 

Thanks,

Andrew

[blitz]

I get the same bubbles in the overflow on my '02 2.5. It's been happening for about a year with no increase in severity or abnormal movement of the temp gauge, although I do get some dry, black, flakey residue in the O'flow tank (carbon???).

 

The only way to know if it is combustion gas or not is to have the bubbles sniffed for hydrocarbons, which is something I haven't done.

[Setright]

Both my Subarus have done this. My old EJ22 and my present EJ201. I think it's normal, and have never investigated this phenomenon on other cars, which probably do this aswell.

 

My logic is this: Once the fluid has expanded and slipped past the radiator cap, it is only under atmospheric pressure, and therefore begins to boil and sends vapour bubbles into the overflow tank. It only needs to be around 90 degrees celcius to give off steam, and it's easily that hot when it leaves the radiator.