Just replace the pump. The March pumps are nice because they are
small, quiet, and draw little current. I doubt if losing prime caused
the failure but it might. I have had mine lose prime but the high
pressure switch cuts off the compressor in a short time. Jabsco
makes a pump for refrigeration but it is physically larger and
draw more current. It is self-priming though. In my case, the
pump lost prime and cycled on and off for several hours before
I discovered the problem. If your boat was left alone for an
extended period of time and kept activating just to be shutdown
due to high pressure then I suppose that the pump may have
wore out. That could also explain the other problems of a loose
belt, etc since continually cycling on, building up head pressure
due to the failed water pump and then cutting off via the high
pressure switch will definitely be hard on the compressor and
probably stretched the belt.

Doug
s/v Callista

"Jeff Morris" wrote in message
...
I have a Crosby 1/2 HP DC refrigerator/freezer on my boat, which normally
runs
an hour or 2 a day. Shortly before I hauled out for the winter, I found
the
system in dire straights. I'm not sure about the "cause and effect" but
the
belt was very, very loose, it was making bad sounds, and I didn't think it
was
pumping water. I tightened the belt, but it was then overheating, and I
didn't
think the water pump was running.

At the time I thought maybe the pump had died from running continuously,
perhaps
running dry, so I brought it home for dissection. I finally got around
to
checking it out. Its a "March 809 BR" with the inline bronze head. When
I run
it without the head, it spins and hums. When run with the head it make a
horrible, screeching noise. Is that simply because its running dry, or
does it
need more help? Nothing looks obviously bad, but the shaft holding the
vanes
seems to have uneven wear.

As long as I have it all apart, is there a better pump that I might use?
This
is below the waterline, and needs help priming. Its possible that losing
prime
was the trigger for my current problems. I do like the fact that this is
quiet
and small, because it lives under the floorboards in my kid cabin.

Any comments appreciated,
Jeff