Checking the Air Bypass Valve When Filling a Car with Coolant

Video Transcript

"Hello, I'm Mark Blocker with Expert Village. In this segment were going to cover the heating and cooling system. In many of today?s new automobiles they have an air bypass valve installed on the cooling system. As I described before there is a thermostat valve installed in the engine. When the engine's cold l this value will be closed. So when we fill the radiator and cooling system with coolant that valve is going to close trapping air pressure inside that head. If we fill it up without bending that air pressure, were going to have a big air pocket in there. That air pocket will not allow coolant to get to the thermostat to heat it up and open it. Thus could cause the vehicle to over heat. Not function correctly air trapped in there can cause hot spots and this could lead to a variety of different problems. So we want to make sure were filling the system to be sure it's absolutely full and free of air. Honda's are equipped with a bleed valve. This is generally located on the thermostat housing in the back. It looks like a little petcock, and by loosing it up, it will open up and allow air to vent, thus relieving the air pressure trapped behind the thermostat allowing us to fill the system completely with coolant. So were going to loosen that valve at this time. Please watch are next segment on filling the vehicle with coolant part two."