[whited44]

Just thinkin outloud here.. 

I found all 4 valves.  I ran the Aquahot preheat today to try to isolate the Aquahot loop to see what valves warmed up the fastest with no real concrete outcome.  Valves 2,3,4 warmed up and 1 was cold.  

From what I’ve read about semi’s with 60 series motors is that the inlet to the heater core is up my the thermostat (valve 2) and the return is on the suction side of the back of the water pump (valve 1).

Valves 3 is almost impossible to get to. I need longer arms.  Once they go over the transmission I can’t see where they go.  

I’m going to close valve 1 and 2 and fire it up to see if the aqua hot still heats up.  

Let me know what you guys are thinkin