[C38] Changed seawater pump impeller fail

[Pierre Patino]

OK, new information (and I may be an idiot too!).

I got a pressure gauge to measure the output at the Oberdorfer raw water
pump. I was able to estimate around 8-10psi  (the needle jumped back and
forth due to the nature of the pump mechanics) so I thought that seemed OK.
I have yet to find the pressure specs on that pump so I'm not sure. The
flow rate into the bucket as stated earlier is definitely "enough" and
around 2-3gal/min so I believe that's close to spec.

I then hooked up the dock water line to the outlet hose which leads to the
heat exchanger. Using the least amount of water pressure I could muster by
barely squeezing the sprayer's handle (sprayer was coupled to the hose via
a barbed fitting) I was able to see water coming out of the exhaust. So now
I'm back where I was, completely perplexed.

I thought about something a colleague at work said: "did you purge the
line?".  Well, I've never done this before when changing the impeller so I
thought "why not?".

I was extra careful when disconnecting the dock's water hose from the hose
to the heat exchanger and I kept my finger in place to keep the water from
spilling out. I also raised the other end of the intake hose above the
water line. I carefully fitted them together and then tested again.

Amazingly, this worked! Water flowed out of the exhaust for several minutes
after turning the engine on.
Problem fixed? Time will tell.

Questions:
Am I an idiot for not purging the line? I've never had to do that before.

Also, I paid close attention to the water coming out of the exhaust. The
flow is  quite uneven. A bunch of water comes out and then much less and
then a bunch more and so on. Is this expected?

Thanks again!





On Tue, Mar 2, 2021 at 8:33 PM Max soto <maxsoto at gmail.com> wrote:

> Wow, honestly this is a though one..  years ago I had a persistent problem
> that there was no water in the exhaust, but it happened every now and
> then...  turned out it was a little piece of mud or barnacle that was
> trapped between the thruhull strainer and the barbed fitting on the other
> side of the valve.  That piece seemed to have life of its own. I blowed air
> through the hose and easily heard the bubbles coming out on the water, so I
> thought the intake was not the problem.  This piece was freely moving in
> the thruhull and clogged the intake every now and then. .. just my two
> cents.
> Regards,
> Max Soto A.
> +506-8312-1367
> Alajuela, Costa Rica
>
> On Feb 8, 2021, at 20:44, Pierre Patino <pierre.patino at gmail.com> wrote:
>
> 
>
> Hello All
> As the subject implies, I failed to do this properly I believe. I bought
> the replacement impeller parts and removed the old one. Removing the old
> impeller was easy. I cleaned the cavity (there was some salt buildup, my
> fault for waiting too long)  and when I proceeded to put the new impeller
> (looks exactly like the old one), I was unable to put the snap ring back.
> I'm not sure how important this is. In any case, I put the cover on with
> the new o-ring and started the engine.
> Now I notice zero water coming out the exhaust. I feel something's
> buggered up and I'm not quite sure what the fastest way to troubleshoot is.
> Suggestions?
>
> By the way, the intake valve is open so I know it's not *that *operator
> error.
>
> I've made sure the impeller spins by running the engine and checking that
> the shaft has rotated as well as the impeller (taking the cover off and
> putting it back on).
>
> Just before I started on this project, water did come out of the exhaust
> so I know it "used" to work.
>
> I'm perplexed why I'm having such a hard time with the snap ring. I just
> did not want to try jam it in with excessive force. The last time I did
> this I had no trouble. Maybe I need to get yet another impeller kit?
>
>
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