Posting on this old thread..............
I too have a problem with the heater circuit. I have proven that there is flow in the entire heater circuit by removing both hoses in the engine bay from their spigots and running a garden hose through the supply hose (comes off the water pump) and and watching the flow form the return hose. I did see a lot of air purged BUT my return hose does not connect to the thermostat housing as stated by a few on this thread - mine connects to the the engine block just above the water pump.
My thermostat housing has connections for the supply and return from the radiator, supply to the water pump, hoses to the top and bottom of the expansion tank and return from the carbie. Supply to the carbie comes off the heater supply spigot on the water pump.
Playing around a little, I also reconnected the supply hose to the water pump, left the return hose disconnected, plugged the return spigot on the block and ran the engine. At idle there was little flow, upon revving the engine I saw some flow, but nowhere near what I would expect given the revs. Previously, I have replaced the heater valve inside the cabin with a new plastic unit. The hose leading into the valve is hot, the other is not - and this is where my question begins.
1. Have I reconnected the hoses in the cabin the wrong way around?
2. Is there a wrong way around?
3. Does water flow from the valve into the heater or from the heater into the valve? (this will tell me if the hoses are indeed the wrong way around):bang:
Suggestions?