Westerbeke Stopped Running

[Fisk]

My Westerbeke 10Two stopped with a bang and I was hoping to get some advice with the first round of diagnostics.

It happened at the end of an hour plus motor back to the harbor. About 20 minutes in, I heard a light rattle coming from the engine compartment at a higher RPM. Throttled down, the rattle went away and continued the trip. The final approach to the harbor involves fighting a three knot tidal current with swirling eddies (we call it the washing machine). Well, I gave the throttle a push to get through a tricky spot. That's when the engine gave a loud BANG and stopped. Luckily the current pushed us away from the rocks and a some nice people in a cruising tug boat pulled us to our mooring field.

My initial thought is some part like a valve or rocker arm let go and got lodged. The engine was not overheating and there was oil in the sump. The prop turns when in neutral. Any ideas of what I should start to look at?

[motion30]

Try to turn the motor over with a breaker bar on the crank pully

[Fisk]

Thanks Motion, I'll start there.