When I stop my baleno '99 after driving a while, it makes gargling sounds in the coolant reservoir bottle and water comes out of the reservoir, and I have to fill it in again. Fan is automatic, and it works okay. When I connect the fan directly, there is no such gargling but water level drops a little in the reservoir bottle. The temperature needle stays in the middle. I have got the radiator serviced and changed the thermostat valve. What could be the reason for that gargling in the reservoir and water coming out? I'd be thankful for some advice from my experienced friends here.