I was reading the thread from a while back about doing the heater core bypass and never found out how exactly the 48re guys were doing a bypass to keep a continuous coolant loop from the top of the head for cooling. I pm'd a couple members to get more info. and was about to put together a set of ball valves and tees and started thinking that would sure be a lot of brass wt. under the hood and with quite a few connections for potential leaks anyway.

I came across this thread http://www.dieselwarden.net/ford/coolbypass.html and went and picked up the 4-way valve at NAPA today. It says it provides a constant loop with the valve closed. I water tested it and it seems to work although there is some leaking from the other lines. Not sure if under vacuum pressure the valve may close a bit tighter.

Now, the question is, where can I get vacuum power to tee into and run this thing? Is everything electric controlled now; a/c actuators, cruise, etc.?

 

there is no vacuum source unless you install a vacuum pump.