Heater core bypass
 

I have to bypass the heater core in my 2001 Expedition 4.6L today. Can anyone tell me how to do this? Any pictures?

No pictures, but just remove the heater hoses where they go in to the firewall, and connect them together with a short piece of copper pipe and a couple heater hose clamps. Or, remove the hose that goes from the water pump to the firewall completely, then remove the firewall end of the other hose and connect it directly to the water pump. If the relative sizes of the two heater hoses make this impossible, then revert back to my first suggestion.

You have the quick clips attaching heater hoses to the HC, so it is not a worm hose clamp type deal. I looked around for a splice tube with those ends on it when my 97 HC was leaking and could not find one. You could always cut both hoses and add a typical hose splice between them. That was going to be my approach, but just did the core instead.

Heater Core By-Pass
 

On my '97 one engine heater hose connection is 5/8" and the other is 3/4". Disconnect the two at the engine and be prepared to catch/loose some coolant. Unless you have the special removal tool, you'll probably want to leave the other ends attached to the heater core.

Four hose clamps, two lengths of 5/8" and 3/4" heater hose, a 5/8" x 3/4" plastic adapter and some coolant/water and you'll be good to go.

If you pop the coolant cap before working on the hoses, you won't loose enough to worry about.