Why do they have the three way in the heater hose. my heater hose is old and leaking at radiator. can i just run hose to heater core to block and another heater core to water pump and plug radiator? Why the bypass?

 

I'm guessing this is in the auto truck? I just replaced all the heater hoses on one of mine, the F350 with E40D, and it had that same three way setup. I just took a hacksaw, cut the crimped clamps off the tee part, took the old hose off, and shoved new ones on and then hose clamped them. For $2 worth of hose, it seemed to be best to replace as original.

I did notice the fitting in the rad only has a small hole in it to feed that hose, I suspect it would act as a 'bypass' for the thermostat. I can see it doing one of two things, either the heater core gets warm while the thermostat is closed, or, it lets some heat into the rad and therefor the tranny cooler so that in winter the tranny fluid gets warmed up a bit on cold starts.

Then again, I'm basically guessing, so could be totally wrong on both ideas!!

 

thats right.
it helps warm up the radiator/doubles as a "warmer" as the trans fluids flows through this section of the rad,the trans fluid is warmed up faster from the engine coolant.
this helps the trans warm up quicker of course and helps get the unit up into it's ideal operating temp for max efficiency sooner.

i wouldn't bypass this myself.id repair it like grey did.

 

gumper i think i passed you on 13 northbound on sunday at about 130 to 3 in the afternoon i was in a silver 09 focus i think it was you anyway were you blowin smoke in the blue an white truck with a plow mount on the front with a headache rack with 2 lights on it spread wide???? it was just south of polo by that old grain elevator

 

Eh, one more connection to fail IMHO - I got rid of mine, and my E350 rad has that port plugged anyways.