Most pre-98 Honda's have them. Reason being is that the t-stat housing is higher than the radiator fill. So air gets trapped. If it has a bleeder valve, make sure you use it or it is gonna over heat. Fill the radiator, crack open the bleeder and fill the radiator with more coolant until it starts running out of the valve. Close valve and fill radiator the rest of the way. THEN you can start the car.