AOA! Water level of radiator and bottle gets very low after 10-12 km drive. It remains on same level without driving. I have changed radiator cap cover as it is maintaining the pressure. I recently plugged in the heater pipe and changed my clutch plates and pressure plates and then i realized that water level gets low after every drive and car gets over heated.. I went to a mechanic he checked into my car and said that there are little bubbles rising in the radiator its mean gasket is leaked and it pull off the water outside through bottle. He also checked for if there is any leakage from heater pipe or not but he confirmed it with no. I have no trust on that mechanic as he didn't checked it thoroughly. Can you please suggest me why it is happening and what should i do. Is Gasket is responsible for it or how should i check if there is leakage or not?