Mercedes-Benz S500 Car Heater Bypass Tube Replacement at your home or office.

What is the Heater Bypass Tube all about?

The heater bypass tube allows a small amount of coolant to circulate throughout your car engine when the thermostat is closed. It bypasses the thermostat, hence the name. Some engines are equipped with bypass hoses, while others have a bypass passage that forms a part of the cooling jacket in the engine. This is really just terminology – the effect is the same.

The bypass tube prevents excessive pressure from being built up within the system, delivers a bit of heat when the engine is started, and allows for even cooling from the point of startup. When the thermostat opens up coolant flow in your car, the engine begins to cool. The car thermostat closes a bit and increases coolant flow through the heater core and the bypass hose.