My car has an overheating problem. After driving several hours temp gauge goes up and down. When going fast temp is normal. but when slow down or at traffic it started going up. Mechanics who checked the car said cooling system, fans. radiators are fine. i have done a radiator clean also. I found out that previous owner has removed the thermostat. So i put a new thermostat value. Before putting the thermostat there was only over heating problem even after i drive from Colombo to kandy and no boiling. But after putting the thermostat it boils after climbing the kadugannawa. I took to the honda kandy dealer willies. They checked and final decision was. There is a small crack in the head gasket. So the compression goes to the cooling system and coolant or the water form radiator goes to the overflow and fills.