Quote Originally Posted by Gil_J View Post
I recently discovered two heating system valves that were leaking. They were screw type vales, like the 2 remaining, and I replaced them with ball valves. I have 4 valves that are visible and am not sure what each controls. They are pointed to with blue arrows. 2 are pointed to but shown in the next photo. The hoses are a bit difficult to trace. I know that the lines go to the Webasco diesel heater and the engine and who knows were else. There is also a round black device (red arrow) in line with a T fitting and 2 other fittings. What is it and what does it do?
Gil,
The red arrow points to a temperature controlled engine coolant bypass for the Wabasto heated coolant. The device, don't remember the name, is intended to keep heated coolant from the Wabasto from circulating in the engine until the water has heated to a certain point. The intent is to heat up the cabin heaters first, then the valve will slowly open and allow water warm coolant to circulate into the engine.

So if you want to heat up the engine coolant for cold starting, you will need to run the Wabasto for an hour or so. That is what I do.

Hector