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  Topic Review (Newest First)
3 Weeks Ago 08:28 PM
mpoisson
Re: rebuilding Oberdorfer Pump

Good news....it looks like it's fixed. I took the raw water hose and ran directly to the water pump and it primed the pump quickly. Re-assembled the rest of the system, ran to the pump dock and back and she maintained 165 degrees. Note, I'm in Arizona and it around 108 outside right now. Thanks for all of your suggestions.
3 Weeks Ago 07:15 PM
eherlihy
Re: rebuilding Oberdorfer Pump

Quote:
Originally Posted by mpoisson View Post
Thanks Gary, glad to hear that the gasket fixed the problem. My new impeller came with a paper gasket. I ordered from Catalina Direct and both fit perfectly. You now have me wondering though. When I removed the old impeller, there was no gasket at all, only what ever sealant the last owner used. I do have another question. What is the proper position of the adjustment/valve on the underside of the pump?

Thanks for the picture, it is a match for what I have.
Then it would appear that you have an N202M -03 or -07



If your pump has a groove machined into the body, then it is a N202 pump and you use a rubber gasket (#3 in the diagram above). If not, it is a 202 pump, and it uses a paper gasket. There should be no "sealant" other than one of these gaskets.

That "adjustment" is a plug, that can be removed to prime the pump (if you can get water into it).

I suggest that you simply call Depco, and order a new pump.
3 Weeks Ago 09:09 AM
mpoisson
Re: rebuilding Oberdorfer Pump

It is a 5411 model engine.
3 Weeks Ago 09:07 AM
mpoisson
Re: rebuilding Oberdorfer Pump

Thanks Gary, glad to hear that the gasket fixed the problem. My new impeller came with a paper gasket. I ordered from Catalina Direct and both fit perfectly. You now have me wondering though. When I removed the old impeller, there was no gasket at all, only what ever sealant the last owner used. I do have another question. What is the proper position of the adjustment/valve on the underside of the pump?

Thanks for the picture, it is a match for what I have.
4 Weeks Ago 09:25 PM
travlin-easy
Re: rebuilding Oberdorfer Pump

Mark, when I replaced the impeller on my Oberdorfer on my Atomic 4 the first time, I made my own gasket from gasket material I purchased from a local auto store - big mistake. The pump would not prime. I called Moyer Marine and told them what I did, and right away they solved the problem. They sold me a replacement gasket that was only about the thickness of a single sheet of paper. I installed the new gasket and the pump worked like a charm.

Here is the pump I have:



Hope this helps,

Gary
4 Weeks Ago 08:49 PM
eherlihy
Re: rebuilding Oberdorfer Pump

mpoisson,

What make and model engine are you working on? Several different Oberdorfer pumps were used on several different make and model engines. Most references are to a MN-202-15 used on a Universal M12/M15/M18/M25/M30/M4-30/M35/M25-XP/5411/5421
4 Weeks Ago 08:20 PM
mpoisson
Re: rebuilding Oberdorfer Pump

I appreciate your quick response. I read on the forum to coat with soap prior to installing the impeller also which definitely helped getting it in. I'm going to try to connect the water source hose direclty to the water pump intake to take out the filter and associated hoses. It's perplexing, I know I'm getting pressure in the pump due to the amount of air coming from the out put of the pump with the 'discharge' hose disconnected and the amount of pressure I see. It's a pretty simple mechanical system which is why I'm perplexed. If it doesn't work connecting the hose direclty, I'll order a new water pump. however, my pump base looks nothing like the one in the future above. It looks like there are only 2 connecting bolts. I can send pictures if there is a way. Thanks again.
4 Weeks Ago 07:05 PM
eherlihy
Re: My experience, and a few references

Quote:
Originally Posted by mpoisson View Post
Thank you for the thorough report! I have a question regarding priming of the water pump if needed.
I replace a fried impeller and gasket today, made sure all water sources/hoses are clear. Sealed everything up and still no water. I did confirm that the impeller shaft is engaged and spinning when the motor is running. Is there something I'm missing to prime the pump?
Thank you in advance. Mark
One trick that I have used to get my pump to prime is to coat the surface of the impeller with liquid soap. This usually gets the pump to work right away.

The only time that this has not worked, was this year when working on a client's boat. I believe that something that my client did in the process of winterizing the pump on his boat created a leak in the pump housing. We solved this by simply installing a new pump, rather than chasing our tails endlessly. 20 minutes later the new pump was installed and everyone was happy.
4 Weeks Ago 04:03 PM
mpoisson
Re: My experience, and a few references

Thank you for the thorough report! I have a question regarding priming of the water pump if needed.
I replace a fried impeller and gasket today, made sure all water sources/hoses are clear. Sealed everything up and still no water. I did confirm that the impeller shaft is engaged and spinning when the motor is running. Is there something I'm missing to prime the pump?
Thank you in advance. Mark
04-27-2016 09:39 PM
MastUndSchotbruch
Re: rebuilding Oberdorfer Pump

Quote:
Originally Posted by eherlihy View Post

I have since learned that the "C" clip is NOT NECESSARY! It was fitted by Oberdorfer to aid in shipping..
That explains something. I changed my impeller last week, and each time I have done it I wondered why there was the C clip. It just seemed to hold -- nothing! I always put it back since, after all, the engineers who designed it must have known what they were doing, who am I to mess with their design?!

So know I know!
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