I've now got all the manuals and I'll look at the wiring diags. I've got
the heat exchanger and water pump off.. just the inlet man to remove
before I can lift the head.
What model Yanmar do you have? Larry is correct that all of the smaller
Yanmars commonly used in yachts have a warning system - both low oil
pressure and high water temperature. The Yanmar panel has warning lights
and a warning buzzer.