No Hot Water?

[Leo]

After motoring we always have hot water for a shower and cleaning up. We had none at all after motoring for over an hour. The engine temp is normal and I found no obstruction in the water tank exchanger. I plumbed in a bypass before the water heater years ago because it did overheat without it.
Do I have a fresh water pump problem? Pumping enough to keep the engine cool but not enough pressure for the smaller lines in the tank? And last but not least how do you test a water pump?
The engine is a 1981 Westerbeke W40.

Len

[INCOMMUNICADO]

Leo,If the cerculating pump isn't leaking from around the shaft the pump is fine.I would start looking at the water circuit going to and coming from the water heater.I hope this some help.Allen

[Leo]

thanks for the input! I have been advised that it could be an air lock too. Hope so better than rebuilding another pump.

[ishmael]

Airlock is a good try.  Also as a though check the thermostat.  Could be stuck partially open.  Check to see if the engine is running a little hotter than usual.