No raw water flow (again) - oil on pump shaft

[kable]

Hi there, trying to help out a racing friend and his Olson 911 w/ a Universal M-18 and a Sherwood water pump.

The other day after a calm day of sailing we powered up the engine to head in and the water wasn't flowing.  We immediately turned off the engine and just sailed into the harbor.  The raw water pump was warm/hot, the immediately obvious things were checked, raw water filter and through hull valve.

The next day he had already removed the impeller before I had arrived so I wasn't able to test if it was spinning, if water was flowing through it and out the hose on the other side.  We used the zip tie trick and put a new impeller back in but couldn't get the retaining clip back on the shaft.  We just quickly put the cover back on to see if water flowed.  Started the engine and sure enough, everything worked.  So we took it back apart and figured out how to get the retaining clip back on and then re-installed.  Now it didn't work again???  Took it apart and we think the shaft wasn't quite aligned w/ some 'ring?' deeper in the pump that the shaft goes through.  We put it all back together again and everything worked.  I did notice a tiny bit of oil on the end of the shaft that meets the engine area.  Later that night I looked this up because it doesn't seem right.  We checked the oil to make sure water hadn't gotten in, seemed good.

Next time out, checked the oil, all is good.  Did this for a couple outings.

Last night, after the race, heading back in, the water quit flowing again.

If we knew what the problem was and it was the pump, he is ready for the Oberdorfer replacement.  But we really don't know what the problem is for sure.

I have seen references to self-priming and some say its an issue some don't.

I guess my question is the tiny bit of oil on the shaft, this doesn't seem right.  I have seen references to the "shaft seal burning up".  What would the symptoms be for this?  Any ideas?

Thanks,
kable

[Stu Jackson]

Sounds like the seals.  Here's how to do an Oberdorfer seal replacement:

http://c34.org/bbs/index.php/topic,6766.msg63510.html#msg63510

There is a Sherwood seal replacement article by Ron Hill, either in the wiki or the tech notes online.

Most all agree the Oberdorfer is a better pump.  Ken Kloeber wrote a "Why" article, It's in the wiki under engines.

[Ken Juul]

The pump should self prime, to some extent. You mentioned racing, is it possible the boat was heeled to the point where the intake hose would drain past the self prime point?  It is also possible the inside of the case has become worn to the point where the impeller can't make a good seal, which would make it less efficient.

Which end of the shaft had oil?  The engine end or the impeller end?

If you think the pump is worth saving, I just rebuilt my sherwood 908 for around $100  for bearings and seals.  Lots cheaper than a new pump.

[KWKloeber]

Kabel,

Oil exactly where?

There are SOME issue with losing prime, but it isn't all installations/conditions and not a certainty. 
A lot depends on the condition of the impeller, case, cover etc etc etc. 
Everything that creates the suction and water flow, wears over time -- and the amount of wear affects (even marginally) the pump flow, priming, etc.

Are you sure it's the correct impeller 0 I;ve had people buy them and they are the wrong ones by a very slim fit margin.

How old is the pump and ever fully serviced?
When was the impeller last changed before this and why? 

I've had situations where machining the cover fixed a no pump situation (not on a boat) - the wear on the cover created just enough loss in suction.

It sounds like it MIGHT be time to just bite the bullet.

Cheers,
Ken K

[Ron Hill]

Kable : If there is oil on the end of the stainless shaft that mates to the slot in the engine - that's normal!! 

[kable]

Just to close the loop, he purchased a replacement Oberdorfer and everything has been working great since.  He is planning on rebuilding the current one for a spare.
-kable