gratian

Just start the car after several month and the water flush out...Could be the water pump get stucked? The electric fan starts to blow when water gets out, so the thermostat is working...
Also the upper water hose seems to "breath"/pump, like some pressure builds up there...

Thanks!

Ish_944

You've got a coolant leak somewhere, possibly at the heater hoses. Then as the engine heats up, the air in the system expands and pushes the water out through the little pipe at the back of the expansion tank.

Find the leak, bleed the system, done.

Yet, I'm still having this issue after literally replacing every single part of the cooling system...

gratian

I wish you are right...
I start the car every 2 weeks for about 10 minutes...It was ok for years, but this time get into trouble. I have to take out belt cover, to be shure that water pump is turning...
10 years ago, i have to replace water pump for the same reason...
One drop of water in that bearing and after one year, most of the time not moving, rust everywhere...