coolant turning into foam

Conjecture: Possibly from combustion gasses getting into the coolant through a blown head gasket or cracked head?

Year/Model???

Are you actually seeing "foam"/bubbles or are you mistaking "stop leak" for foam like people often do?

Wouldn't such a condition manifest itself in other ways, such as in really lousy engine performance?

'95 SL2

I smelled coolant while getting out of the car after a ten mile drive, and inspection under the hood revealed that coolant had been forced out of the overflow tank, with the surrounding area sporting a very foamy coating.

During daylight the next day, the cap was removed, and what was visible in the overflow tank was foam.

Not necessarily. Get it checked out ASAP to prevent major damage. Have you looked at your oil lately? A head gasket can leak between the combustion chamber and cooling jacket, or between the oil and coolant, or from combustion chamber to the oil. Each will provide a different experience. If the leak is small, it can be a long time before it becomes noticeable.

Good luck and post what you learn to benefit others.

Bob

Out of risk of activating yet another flame war over the subject - could a blown head gasket possibly lead to a cracked head? I could imagine if you've got co,bustion gases blowing out, you'd get a localized hot spot and all.

And hey, is it me, or are head gasket 'issues' a popular defect in a LOT of cars out there from everyone?