Hi,

problem with boiling water after 5-6 km of driving...temp gauge is about quater? No racing, just light driving about 70-90km/h, outside temperature 28°C.

When I arrived to garage, heater tank was like "balloon" and water was boiling. (temp gauge still under the quater).

When i turned off the ingnition, boiling raised! It boiled about 2 minutes.
Then I started engine, remove cap from heater tank and water is slowly rising up to the top of heater (cca 30sec up top). I saw bubbles comming out from pipe...but same bubbles I can see if I turn of the ignition so I am guessing that water is boiling inside engine (this makes bubbles) - But there is a question why is water boling inside engine? Car stays for a few years, Last year a cleand water system with 10pcs of cleaners (flush) there was a lot of "mud" in system...Any idea before I demount the thermostat and water pump?

Thanks! (sorry for my english)