Yanmar 2GM20 FV & External Water Heater

[OKCUBye]

Can anybody tell me which inlets/outlets to use when hooking up an external water heater to my Yanmar 2GM20FV?

standing in front of the engine and looking at it: alternator is on the right, water pump">raw water pump on the lower left...

There are 3 ports on the top of the engine at the thermostat...one on the very front of the engine on the thermostat housing, one slightly lower and to the left of that (below the heat exchanger) and one on the right side of the thermostat housing immediately behind the very top of the alternator...

i tried the top and the one to the left in a loop, put in a clear hose to check flow, but nada...those were the ones i was told previously, but

tried running the engine for a few minutes with the thermostat removed...

i checked the thermostat by removing it and putting in a pot of boiling water with a thermometer...thermostat works perfect...but still no circulation through the external loop

thanx!

[OKCUBye]

got it...