[Guy]

Thanks Richard.
I am embarrassed to admit that while I was fighting a leak going to the cab heater I added automotive prestone coolant. I will drain the system, refill with distilled water, run to operating temperature ,drain the system and refill with Fleetguard oat. Cheap insurance. I don't see any fittings to bleed air from the system, so I will just refill and bring to operating temp, cool down, check coolant level and repeat.