There should be either 2 or 4 hoses coming off the 8V92 to feed the heat exchangers. These hoses are on the driver's side of the engine near the radiator. On mine there are four hoses, two going to the exchangers and two bringing water back. One of those hoses likely goes to an auxiliary 12 volt water pump that helps pump the water to the front heater core. If you have that auxiliary water pump you might try turning it on by moving the dash heater control to max heat and running the engine. That may help clear one major source of air. If you have the four small water lines on the engine, one will go directly to the water heater heat exchanger and the bay heater exchanger. I have not had a problem with that system not purging itself with the engine running since there is not a valve and pump in line but you can verify that the system has water in by carefully loosening one of the radiator hoses going into the water heater and verifying that coolant is in the line.
Tom's coach only has the one circuit (2 hoses) that goes through the solenoid valve and pump. Without the pump running water does not flow to his water heater engine heating system. Mine has the four lines so only the dash heater is affected by the valve and pump. If water drains out of the return line the engine can't pump water back into it through the closed valve.
If this suggestion doesn't work, let us know and we will try some other tricks.
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