Originally Posted by Loon
Loon here. Cruising the San Juans and have a question. We developed a noise at 1500 rpms which went away at a lower rpm. A wife complained of lukewarm water while showering. I'm positing the fresh water pump is the culprit however no leakage. It is the 6.354M starboard engine,
The impeller is metal and seldom fails, it's usually bearings that doom the pump. if the engine isn't running hot, fluid levels are normal and no leakage from the bearings....My guess would be it's something else.
I only had this happen once with my old hot water tank. Turned out to be a build up of "crud" at the engine hose bibs (where the heater hose from the tank connects to the engine) restricting the coolant flow to/from the water tank. Cleaned it out with a screw driver and battery brush. If you're at a dock where you can take the hoses loose and catch the coolant, you can check that out pretty easy.
PS: Also try blowing through the hose end to make sure there isn't a restriction in the water tanks heat exchanger.
The noise could be another issue that you might want to trouble shoot right away as well.