engsol wrote:

You mention above that the engine was "red hot" after shut-down. What were
the indicators? The temp gauge only? "Frying" noises and smell of a hot engine?
Smoke/smell from hot paint? Could a stuck-closed thermostat be the problem?

We bought our boat used and as we were taking it home it appeared to overheat.
I sweated about that and got a diesel guy in, and he found that it was a
malfunctioning voltage regulator. It was cranking up the temp gauge.

If the temp gauge was the only indication, I'd certainly recommend a
consultation with a qualified mechanic before you take your engine out and shoot
it.