Quote Originally Posted by Jonty View Post
Thanks for this. Yes the return line is very close to water line but I have emptied a bit. Come to think of it the bubbles are worse after is emptied some so maybe you are onto something as it’s probably stirring up even more. I was getting a very small amount of overflow when the reservoir half or more full but now it’s only 1/4 it is not overflowing at all or loosing any coolant (or overheating). I’m also wondering if there is a bit of contaminant in the coolant (as it was recently changed) that might exacerbate the bubbles (it is really a kids bubble bath in there not just a few here and there).
If you are getting foam like soapy water, you may have a contaminant that has amended the surface tension of the coolant (Like adding dish soap to water) Giving it the ability to hold bubblers of air.
My coolant bottle has been at half full for a 1000 miles, over flow tube is bone dry after even the longest drives in mid Florida summer. My temperature gage fluctuates between the 1/4th mark, and about half way between that and the 220 mark.