Raw Water pump leak

[Stu Jackson]

Just to be clear, the issue is leaking past the outer lip seal so he needs to pull and inspect the shaft, not just pull the impeller from the shaft.

When one tries to reinsert the shaft/impeller as a unit there's two locations (180 degrees apart) that the shaft fits back onto the camshaft.  If it's not lined up correctly it's difficult to rotate the impeller when inside the water chamber to get the shaft lined up with the camshaft.
 
That's why it's best to mark the position of the impeller when removing it.

Ken's right.  This issue comes up so often that I took pictures of the shaft and what's inside behind the gear case cover.  Those photos are in this link:

Oberdorfer Pump Rebuild 101 - http://c34.org/bbs/index.php/topic,6766.0.html [Link added to main page of C34 Tech wiki]

[junaido]

I had the pump rebuilt. New shaft seals, bearing and impeller shaft. It is not leaking anymore and water flow out the back is good. However, it occasionally doesn't spit water when I turn the engine on. Yesterday I went out for a sail, exhaust water all normal on the motor out. On the return when I started the engine I noticed no water coming out the back. I shut it off and restarted, still no water. Checked water strainer (clean), restarted, still no water. Called for tow (boatUS said 1.5 hour ETA) and sailed around for a bit. Started it again after maybe 20 minutes and the water came out the exhaust immediately. Motored back to slip without any problem. This happened once before as well during my recent San Juan islands trip when the pump was leaking. Any idea why this is happening?

[Ron Hill]

Jun : WOW! One of the hardest items to trouble shoot is an intermittent anything!!!
 
I'm going to guess that you've got something in the raw water line from the output on the pump to the nipple on the exhaust riser that periodically stops the flow of water???

Here's what I'd try: Look at the elbow attached to the output of the raw water pump and make sure it is clear (no broker impeller blade hiding in there - maybe from a PO!!). Then I'll suggest that you remove the Hear Exchanger and clean it out (probably Never done in Many years!!) you just might take it to a radiator shop and have them boil it out!! Check the hose from the Pump to the HE to make sure it is clear. Then check the output hose from the HX to the nipple on the exhaust riser to make sure it is clear (this includes the anti syphon valve that's inbetween the HX and that nipple.

If all of that route is clear - All should be OK.  Good Luck 

A few thoughts

[junaido]

Hi Ron,

I replaced the hose from the raw water pump to the heat exchanger. The old impeller was not missing any vanes. The heat exchanger is probably about due for a cleaning. I will look into that next. Thanks.

[KWKloeber ‘84 C-30 #3573]

it occasionally doesn't spit water when I turn the engine on.

There are times when the seawater "system" loses prime when heeled and for different reasons the pump doesn't pull the prime.  It can be due to poor fit of the impeller against a (worn?) cover, an air leak somewhere before the pump, or a partially blocked external strainer/thru hull.

Exactly why it happens and when who knows? but it can depend on specifics of the setup.

On our 30s it tends to happen more infrequently (the engine sits lower.)

IIWMB and that happened I would pop off the hose on the pump discharge to verify whether seawater is getting good flow that far (and the Hx or injection wye is an issue) or no warer (then the trouble is before the pump.)

Lubricate both pump hose barbs (in fact all hose fittings) so that hoses are more easily removed when it's needed.

Saltwater deposits can nearly block off the injection wye!  Make sure you are running the proper thermostat (160°F) and it is opening at the correct temperature.  Too high and the deposits occur more easily.

[Jim Hardesty]

IIWMB and that happened I would pop off the hose on the pump discharge to verify whether seawater is getting good flow that far (and the Hx or injection wye is an issue) or no warer (then the trouble is before the pump.)

That's where I would start trouble shooting.  That is check all the hoses.  If all else looks good I'd pull the pump and take a good look at the camshaft end to make sure it's still good and not damaged and only catching once in a while.
Jim

[Ron Hill]

Jun : As Ken mentioned, the next time there is no water coming out of the exhaust keep the engine running and pull off the output hose from the raw water pump and see if water is coming out!?!
If not then you've nailed it down to a pump problem or the intake/hose/thru hull!!

A few thoughts