Can a Heater Core be Leaking by the Heater Hose?

A leaking heater core can make winter driving miserable.

A heater core is a radiator-like device located inside the passenger cabin of a vehicle. The core is heated by hot engine coolant. Both the heater core and the heater hoses may leak due to wear or damage.

Heater Hose Leak

Heater hoses are flexible lines that carry hot engine coolant to and from the heater core. On most vehicles, the heater core will have inlet and outlet lines that reach through the firewall where they attach to the heater hoses. Leaks in the heater hose will often drip into the engine compartment, but the coolant may also run down the hose and into the passenger cabin.

Heater Core Leak

Heater cores are made of metal and may begin to corrode over years of use. The corrosion may eventually cause a hole to develop or create weak spots in the core that allow it to flex, resulting in cracks that allow coolant to leak. The heater core is most likely to flex at the inlet and outlet lines that attach to the heater hoses.

Repair

Leaks in the heater hose will require replacement of the hoses. Additionally, loose clamps should be tightened and faulty clamps replaced to stop leaks around the clamp. Radiator stop leak additives may repair minor leaks in the body of the radiator core, but larger leaks will require soldering or replacement of the core.

References

• AA1Car.com: Heater Service
• 2CARPROS: How Car Heater Works