bmorrisj

when your looking for bubbles under the rad cap, are you looking for bubbles like blowing through a straw or foam?

roundman

any bubbles at all are not good be they big ones or foam. in the case of foam, try scooping it out with a spoon and then see if it comes back or just fill the radiator up until it just does overflow and then look for the bubbles. bubbles indicate a blown head gasket, but I guess you already knew that right?