From the firewall side, which one is the inlet and which is the outlet back to the water pump, or does it even matter? I can't remember which one is which. My concern is that there might be some sort of check valve in it to prevent backward flow through the heater core and I wouldn't know it until I needed heat. In my haste and disgust when removing the 7.3, I forgot to mark the hoses. Can anyone help?

 

The upper hose on the firewall goes to the water pump,that's got to be the inflow.

 

Supply is on the right, return on the left looking from front of truck. No cv's that I'm aware of , and I've 'messed' with my heater hoses quite a bit!

Following your progress, btw. Keep up the good work!

You rock!

 

The hose to waterpump is return. But that ain't gonna help - he does not have an engine in there... , or if he does it has 2 less cylinders!

 

You are correct, that is the return.

 

My hoses are side by side. I was thinking there is some variation in this between trucks.

That's perfect! That will work out well since the supply on the Cummins is further toward the middle. Thank you for the info. Check another item off the list!