All engine cooling system hoses work the same way. They are pressed onto a connector at both ends, and either clamped, or sealed with an O-ring type seal. This provides a watertight seal between the two components being connected.

Coolant hoses can be damaged by oil leaks. The issue should be addressed in order to avoid damaging the new hoses.

A failing heater hose may cause the vehicle to smell of engine coolant under the hood. If coolant runs onto the heater core inlet or outlet, the cabin could begin to smell of coolant and mildew. Also, the engine may being to run increasingly warmer until the vehicle is repaired. Coolant may leak onto the engine, firewall, and ground, as a defective hose may swell and burst. The worst-case scenario is engine overheating, and possible cylinder head gasket failure.