Losing Prime Raw Water

Anybody else lose prime on their raw water pump when they sail fast and heel?

That used to happen to me years ago. I think I solved it by making sure the strainer cap was tightened down real good. I would use a bit of grease also to help keep a seal. I haven’t had any problem since doing that.

Ron Thompson
Ho’okahiko 97

We had the problem for several years before we finally got it figured out! The early problem was: no exhaust water for a minute or two after starting the engine, after sailing at 5 or 6 knots. It finally came to a head when cooling water was lost whenever we were in rough enough water for the intake to take in some air. The alarm would go off, and we’d shut her off.

Replacing the impellor, and turning over the pump’s face plate (it was slightly scored), made no difference. I finally used a caliper to measure the depth of the pump, and discovered that the bronze pump was several mm deeper in places than the thickness of the impellor! So, water (and air!) was able to pass BEHIND the impellor. When sailing with the seacock in its usual open position, water was pulled OUT of the heat exchanger. Rough water sucked in air that the pump couldn’t recover from, with its weak flow.

The pump was about 17 yrs old and had about 4000 hrs on it. A new pump fixed all the problems. I guess we got our money’s worth out of the old one! I sure wish I’d figured it out sooner.

Hope this helps.
Shaula BCC #58

Ok thanks, 2 different directions to check out. I have 1200 hrs on my engine, 450 during my ownership. Pump is 20 years old, but hardly has the hours Dan’s pump had. I have been in the sea water strainer a few times to clean out some offending weeds. I’ll check both these ideas out. Thanks!

A plug and play complete spare raw water pump is always on my spare parts wish list… WISH being the operative word.

Thanks for the insight guys – any other thoughts out there?