Does it matter?

[In The Ten Ring]

This is how my heater core was hooked up and the original owner (my dad) said he had never messed with the heater. It's a little hard to see here, perhaps even harder for iphone users, but it's about the best pic I have.

[geezer#99]

Right from the factory!
Correct for a six banger. Thermo housing to the bottom of core. Top of core back to the water pump.

[afdcaptain]

I know this is an older thread but is correct that the top heater core hose goes to the water pump and the bottom goes to the intake

[Rufas]

Originally Posted by 69chevytrucker

funny both my heater hoses are diff sizes

Same here. What size hose fits the heater control valve?

[Old Money]

old school way to remember, bottom hose to top and top hose to bottom. no matter how you looked at it. it always worked. old money

[Andy4639]

Ok here is my take. The inlet of the heater core is the bottom hose this makes sure you get all the air out of the core when filling it. Same as a transmission cooler. This should be the line form the intake.

The water pump is pulling the cool water from the bottom of the radiator and pumping it through the engine so it would also pull from the core as well. The pump is hooked to the top fitting of the heater core.

Another note. if your truck has AC and it has heat under the dash when your AC is on your not getting full benefit of your AC. I put a manual valve in the line to insure no hot water comes in the cab when the AC is on. It's worth a good 5 more degree's inside the cab!