[C38] Changed seawater pump impeller fail

Sun Mar 7 18:12:59 EST 2021

Here is an article I wrote for mainsheet several years back may be of help

Steve Smolinske
President

4M Company, Inc.
15660 Nelson Place South
Seattle, WA  98188
425-227-4500

The information contained in this email may be confidential and/or proprietary in nature and is intended for the recipient of the email only.  Please treat all information contained in this and any communication with the 4M Company as such.  Thank you. Before printing, think about ENVIRONMENTAL responsibility

From: Listserve <listserve-bounces at catalina38.org> On Behalf Of Steven Ribble
Sent: Sunday, March 07, 2021 2:08 PM
To: Catalina 38 Listserve <listserve at catalina38.org>
Subject: Re: [C38] Changed seawater pump impeller fail

Pierre,
If you haven't cleaned the heat exchanger you should, hopefully it's your problem, but it needs to be maintained regardless. Some years ago [the listserve] suggested using a welding rod to ream the tubes inside the heat exchanger. If you're not familiar, the heat exchanger is a bunch of small tubes conveying raw water running through a big one that has engine coolant.

The welding rod works well to ream the buildup in the tubes, but the flux coating wears off and is a bit of a mess. My heat exchanger sits above and rear of the engine ( I have a Westerbeke, the Universal was replaced) and once you wiggle into position is fairly easy to ream. There's also a pencil zinc on one end that you should inspect/replace regularly. A paper towel at the far end will catch the crud you ream out. I use my cell phone to photo the hole ends to assure the occlusions are cleaned because it's hard to get a good look.

Good luck, have fun...hope it's the problem.
Steve

On Sun, Mar 7, 2021, 4:52 PM charles <charles at finn.ws<mailto:charles at finn.ws>> wrote:
Only way I could manage was to enlarge the opening in the port locker (sawzall) and then remove water heater (fairly easy) and then put down some foam pads and enter head first turning about in port locker.  Make sure there is someone on deck to hand you all the tools you didn't know you needed!

-------- Original message --------
From: Pierre Patino <pierre.patino at gmail.com<mailto:pierre.patino at gmail.com>>
Date: 3/7/21 11:43 AM (GMT-06:00)
To: Catalina 38 Listserve <listserve at catalina38.org<mailto:listserve at catalina38.org>>
Subject: Re: [C38] Changed seawater pump impeller fail

Yes. I think it's downstream from the pump as well. Next weekend's project is to figure out the yoga to get in there and inspect.

On Sun, 7 Mar 2021, 6:42 am charles, <charles at finn.ws<mailto:charles at finn.ws>> wrote:
It is not the pump!  I am guessing your heat exchanger is most likely plugged.  It sits on the rear of your engine above transmission.  My old one got plugged with zebra mussels that enters system as an egg and grows while engine is off.  There are cleanout ports on exchanger but I opted for a larger one.

-------- Original message --------
From: Max soto <maxsoto at gmail.com<mailto:maxsoto at gmail.com>>
Date: 3/6/21 6:44 PM (GMT-06:00)
To: Catalina 38 Listserve <listserve at catalina38.org<mailto:listserve at catalina38.org>>
Subject: Re: [C38] Changed seawater pump impeller fail

Really weird.  Those pumps are, or supposed to be self priming for up to 6’. How old is that pump?  Look for wear in the housing. Somethings the cam might need to be replaced
Regards,
Max Soto A.
+506-8312-1367
Alajuela, Costa Rica

On Mar 6, 2021, at 14:04, Pierre Patino <pierre.patino at gmail.com<mailto:pierre.patino at gmail.com>> wrote:

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<mailto: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<mailto: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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