So, I'm well aware that if you have bubbles in your coolant while looking down the radiator fill neck w the motor running you have a bad coolant seal. Sometimes you'll get white smoke with this as well.


Here's my problem - I occasionally see bubbles in my coolant. I recently flushed it + have been running straight water for maybe a year or so. (Yes, I know this isn't the best idea, it's given me a **** ton of rust everywhere.) So I'm in the middle of cleaning everything out + flushing it proper. BUT, my add coolant buzzer goes off a lot. I'll top it off every drive.

Here's the weird part - when I let the car sit overnight, then open the rad cap up, it's still pressurized. I can watch the main coolant hose on the top left shrink when I open the cap.


So is my problem that the rust + debris in my coolant system is causing the water to boil, then all the bubbles make a pocket at the top of my rad causing the buzzer to go off? Or do you think it really is a bad coolant seal?

Also, a bad coolant seal will make it so the coolant system won't hold pressure, correct?

 

Not necessarily. Have a sample of the coolant chemically checked for presence of exhaust gases. If they are there, a seal is blown. if not, it is probably something else...

Any radiator shop can do the test...