So I don't know if this has been asked before, but I have no idea what to search for. So for the past few monings I've been checking the coolant tank and it seems like there's way more water in there than there was about a couple weeks ago. It has the white lines on the side of the tank like it's been puking coolant and the tank itself is so over filled it's almost up to the threads of the cap. It was right at the max full line a couple weeks ago, So pretty much I'm just wondering where all this extra water could have magically come from. I'm used to this car losing coolant not gaining it. Thanks for the help.

 

The cap may have not been tightened enough or it needs replacing. Typically, there will be pressure building up and that will help open the thermostat.

 

I changed the cap out probably 3 months ago so probably not that unless I got a bad one. I bled the system that morning and turns out there was a huge bubble in the upper radiator hose. After bleeding the system it seems to be staying at a fine level since. sorry if I'm explaining this bad but I'm just wondering what would cause the bubble to form there. The system didn't have any bubbles a couple weeks ago so I have no idea what would cause it to unbleed itself.

 

Best guess. The old cap that was failing caused low coolant condition in expansion tank. The result of which was an air pocket created within the system. There are TWO bleeding points for the system. One is close to the thermostat itself, in difficult location. Second as you are probably already aware, at top radiator hose near front wall.