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What is a Heater Hose?

Robert Ferguson
Robert Ferguson

A heater hose is a rubber hose used in automobiles, and it transports hot coolant to the heater core. The heater hose connects to the water pump and the heater core, which is located next to the firewall on most vehicles. As the hot coolant passes through the heater core, a fan circulates air across the core, which heats the air and distributes it throughout the automobile's cabin.

Over time, as with most rubber products, the heater hose might become brittle because of the extreme heat and its age. This might cause the heater hose to fail, causing the engine coolant to leak out and overheating the motor. To prevent this from happening, vehicle owners should have the hose inspected annually for cracks, swollen areas or splits that could lead the heater hose to failure. The hose should be replaced if necessary.

Man mowing the grass
Man mowing the grass

The engine should be allowed to completely cool down before one attempts to inspect or replace the heater hose. Exposure to the extremely hot coolant will cause serious bodily injury. Radiator coolant should be handled with care, because it is extremely poisonous.

Before one attempts to replace the heater hose, the coolant should be drained from the entire system. The radiator will have a petcock or valve located near its lowest point, and it should be loosened so that the coolant can drain into a pan or bucket. One should dispose of the old coolant immediately in a safe manner. This will prevent any coolant from leaking onto the ground, where it could be encountered by pets and other small animals.

To replace the heater hose, one should release the pressure valve on the radiator cap to relieve any remaining pressure, then remove the cap. The hose clamp that holds the heater hose on the water pump outlet should be loosened, and the hose should be removed. If coolant is present in the heater hose, it should be drained into a bucket and discarded immediately.

The hose clamp that holds the heater hose to the heater core's fittings should then be loosened. The heater core is very fragile, so pulling, tugging or twisting could damage the heater core, causing it to leak coolant and leading to a very expensive repair. A knife or razor blade should be used to cut the hose away from the heater core inlet/outlet tube, and the hose should be gently removed.

One should then apply an applicable sealant and lubricant to the inlet/outlet tubes on the water pump and heater core and install the new hose. The petcock on the radiator should be closed, and the coolant system should be refilled with an appropriate coolant. The automobile should be test driven to increase the engine temperature, and then it can be checked for leaks.

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