I have 2 2007 BF20D3 with extra long shafts on my catamaran. I am having trouble with one engine alarming(overheating) and consequently stopping, when it can be used but not at load. The engine has had salt remover through it and has had the cooling manifold cleaned and the thermostat and the temperature sensor changed despite no fault found. It has a new water pump and good flow through the telltale but still alarms. When it alarms the block and sensor temperatures are not discrepant to the other engine running normally. Does anyone have any ideas???