No, it makes no difference whatsoever which direction the water flows through the heater core.

 

According to Johnpro (same topic a few months ago), the way you described, with the top hose running to the intake, is correct. The heater will heat either way, but that routing will help keep air out of the core.

 

Can't recall the original routing for sure but I would/do plumb the heater so that the water enters the bottom of the core then out the top.

This reduces the chance of trapping water or bubbles in the heater core reducing the effectiveness of the heater

 

Water goes out of manifold--into water pump ! ! ! ::

Manifold to bottom---Top to suction side of water pump ! Keeps air from being trapped in heater core , also keeps it from gurgling .

 

Don't know exactly what you're working on, but here's a pic from the '65 Shop Manual for a V-8:

http://a2.cpimg.com/image/60/24/13071712-d806-02000125-.jpg

 

WOW>>> you learn something new everyday!!!

 

Mstngjoe,

Thanks for the picture, that clears it up, and makes sense.

Does your manual have a schematic for the I6? I think the coolant flows FROM the water pump discharge (PS) into the lower fitting, and OUT the top fitting to the pump suction on the drivers side. If not, I need to reroute mine.

 

I misquoted johnpro in a post earlier on this thread. He said (back in March) that the hoses were routed just as mstngjoe's schematic shows. :: I waited too long to try to edit it. Sorry John!

Oh, well. I get to start a new year in about 10 minutes..

 

.....I think the coolant flows FROM the water pump discharge (PS) into the lower fitting, and OUT the top fitting to the pump suction on the drivers side....

That's what it shows in the '65 Shop Manual.