Im in process of putting in my Vintage Air system and need to know which way the coolant flows,Im assuming it come from the water pump nipple->- to the heater core ->- back into the engine at the side nipple,Dont want to start it to find out and have it puking my antifreeze all over.

 

FordF250 and I were trying to figure this out, and we found out through various means that the coolant definitely flows from the head port through the heater core then back to the water pump. Here is your proof.

7.3 IDI Diesel coolant filter. - YouTube

 

Thanks Mac did ya let it warm up to full operating temp to be sure it wasnt just the bye pass..

 

It wasn't all the way warm, but it ran for way too long for it to be just residual run off. Plus Ford found a coolant system diagram that confirmed it. It is all in a thread on here somewhere. I'll see if I can find it.

 

Page four of this thread has more info.

https://www.ford-trucks.com/forums/1...mpleted-4.html

 

Well, That would of messed me up I thought the wrong way good thing I didnt cut my hoses yet

Thanks Mac!

 

Glad to help, I thought the same thing, then realized it could flow either way. It does make sense that the water would be coming directly to the heater core from the cylinder head where it is the hottest when you think about it though.

Good luck,

Mac.

 

you also want the coolant flowing into the lower nipple of the heater core, and returning to the engine from the upper nipple. this ensures the core is full of coolant.
hooking it up the other way could result in a waterfall sound coming out of the heater box.