Bongo Fury

That would be really helpful Dandy.
alphabetter - I follow your logic but I would think the only outlet is from the pump, through the main hose, to the rad top If the water flowed the same way through the whole heater system (anticlockwise in your diagram), that would allow cooled water from the heating system to be sucked into the rear of the engine, via the red hose from the heater circuit. Hope that makes sense!!

francophile1947 wrote:That would be really helpful Dandy.
alphabetter - I follow your logic but I would think the only outlet is from the pump, through the main hose, to the rad top If the water flowed the same way through the whole heater system (anticlockwise in your diagram), that would allow cooled water from the heating system to be sucked into the rear of the engine, via the red hose from the heater circuit. Hope that makes sense!!

Ummm sort of, but not entirely.

Are you saying that the connections may be drawn wrong or are you saying that the flow directions are different?

The way the heaters connect to the engine is pretty clear from the diagrams I linked a few posts back. If there is something I have missed on those drawings please let me know. While I agree that a single circuit would be the normal expectation the actual plumbing doesn't seem to be configured to do this.

The flow directions are based on certain assumptions which I agree could be mistaken.

Hi alphabetter
Not drawn wrong, just the flow directions. If the flow, shown on both rear heater pipes of your diagram, was reversed, the whole system would then flow in one direction. The small red pipe, from the red rear heater hose to the rear of the engine, would then act as an intake of cooled water to the engine. This is, of course, pure guesswork without knowing the pathways through the engine, but it seems more logical than water flowing in 2 directions.

The heater coolant definitely hotter first from the head on the driver's side and returns to the passenger's side of the engine.

Does anyone know if there's a coolant supply from the engine block into the casting where the thermostat is housed?

francophile1947 wrote: If the flow, shown on both rear heater pipes of your diagram, was reversed, the whole system would then flow in one direction. The small red pipe, from the red rear heater hose to the rear of the engine, would then act as an intake of cooled water to the engine.

OK now I understand. As is nothing to make the coolant in the heaters to circulate apart from the pump in the engine block all the pressure to drive the heating system comes from the engine. This means that each connector to the engine block either "blows" or "sucks".

If the red rear hose "blows" then it will blow in to both heating circuits as shown on my diagram. However it is "sucks" it will suck from both heating circuits reversing the flow on both the front and the rear heaters.

Dandy's comment would seem to confirm this outlet "blows".

dandywarhol wrote: Does anyone know if there's a coolant supply from the engine block into the casting where the thermostat is housed?

The gasket "15-165" on this page would suggest the answer is yes.

Nobody has added anything to this discussion for a while. Does that mean we all agree? Job finished?