To Bypass the Heater Core: Do I loop the lines or block them off? (1 Viewer)

[GRM]

Looking for some quick technical help: I have a 2FE in my old 40 series. The heater core started to leak, but since I never drive this thing in the winter, I just want to bypass it.

In the process, I’m also gonna clean up some heater hose routing.

On a F series motor, should the line to the heater hose be capped or looped?

I pulled up a diagram to show what I would want to do. Essentially I think I should be capping the heater hose line going into the thermostat housing, and also cap the line that t’s into the lower radiator hose.

Can you help me confirm if this is correct? Or if I need to loop from the lower radiator hose to the thermostat housing?

The diagram shows how I propose to route the heater hoses.

 

[73FJ40]

Block off. Any coolant flow through the heater circuit bypasses the radiator. If ambient temperatures are cool enough to warrant heating the cab, the heater core acts as an auxiliary radiator and it's likely the radiator is over-performing with cold air passing through.

If the heater circuit is looped, hot coolant leaving the head is dumped into the suction line of the water pump, mixing the hot heater circuit coolant with cooled fluid returning from the radiator, raising coolant temperature entering the engine. Obviously, this will not provide the best scenario for engine cooling on hot days or high load conditions.