It sounds like maybe it is sucking air. Check the lines coming into it.
If is worked before then perhaps someone sold you the wrong impeller. Do
you still have the old one?

wrote in message
...
On Oct 5, 9:46 pm, Wayne.B wrote:
On Sun, 5 Oct 2008 17:17:37 -0700 (PDT),
wrote:

It seems to me that this thing should pump even if it does lose prime
because you would expect it to lose prime as the boat heels and waves
pass under. Any thoughts?

Possible causes, more or less in order of likleyhood:

1. Raw water impeller is tired and needs to be replaced.

2. Raw water intake through hull fitting is fouled. I once sucked
in a jelly fish. Barnacle growth is common.

New impeller. Recent bottom paint and defouling. Besides, I can blow
down through the raw water seacock (with effort, it is 1' under
water).

In spite of all the hassle this has caused, it is fortuitous. While
working on the water pump, i saw a big nut under the prop shaft, then
a big bolt, couldnt figger out where they came from. The another,
HUH? I looked all over for their source. Finally noticed he prop
shaft and transmission were slightly misaligned. AHA, HOLY Shi%. My
prop shaft is held by only one bolt to the transmission output and
even that is coming out. This coulda been a truly nasty surprise when
waaaaay out in the Gulf.