How to Hook Up Heater Hoses on Early Engines


The thermostat housed in an engine cooling system blocks the engine cooling system from circulating until the engine reaches a predetermined temperature. Then, the thermostat opens and allows the hot water to circulate. The heater hoses of a vehicle hook to a small radiator that circulates water heated after the thermostat opens while the running engine. The radiator is housed inside a shroud. A blower motor blows air through the small radiator and the shroud sends it into the vehicles cabin for heat windshield defrosting.

Things You'll Need

  • Safety glasses
  • Wrench set
  • Drain pan
  • Screw driver set
  • 4 small hose clamps
  • 2 Heater hoses
  • Box cutter
  • Remove the negative battery cable from the vehicle that you will be hooking up the heater hoses.

  • Place a drain pan under the radiator cock drain. Be sure the engine is cool. Open the pet cock valve and drain the coolant from the vehicle before connecting heater hoses.

  • Locate the two protruding pipes or tubes from the heater core. The pipes should be located on the passenger side of the cowl. If the vehicle is real old it could have a box heater under the seat and the two hoses must run to that heater core under the seat.

  • Locate the two pipes or tubes in the engine bay that supply the heater core with coolant. One pipe should be located on the water pump and one should be located on the engine block or radiator. Beware that sometimes these two pipes have the same heater hose running like a loop to temporarily eliminate a leaking heater core.

  • Cut and connect two heater hoses. One from either pipe or tube on the heater core to the water pump, pipe nipple. Connect the other heater hose to the other pipe or tube on the heater core and run it to the pipe nipple on the block or radiator.

  • Close the pet cock drain in the radiator and refill the cooling system.

Tips & Warnings

  • If the pet cock valve on the radiator is frozen up and not operable, it is acceptable to remove the lower radiator hose to drain the coolant.
  • Remove the radiator cap to aid in a smooth flow of coolant from the radiator when draining it.
  • Always wear safety glasses when working on automobiles.
  • Handle and dispose of old coolant in an environmental friendly way. Coolant may be harmful to animals.

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  • Photo Credit Jupiterimages/ Images
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