Water boiling in the over flow tank need help please.

[ManoNegra]

tired radiator cap not holding pressure thus allowing coolant to boil
happened to me once

[jspaeth]

Originally Posted by ManoNegra

tired radiator cap not holding pressure thus allowing coolant to boil
happened to me once

I think this is what I have, because I lose maybe 1 or 2 cups of water every month or so, but my compression is great, no white smoke anywhere, no oil/coolant mixing.....


If I fill up the rad and fill up the overflow a bit, in a bout a month, the overflow is empty and there is a little bit of coolant missing from the radiator.....

I was thinking that it was because my 15-year old rad cap was allowing coolant into the overflow, and then it was evaporating from there somehow (crack?, not airtight?)