Raw water impeller replacement interval / pump retrofit

[dedgell]

Yesterday I changed the impeller in my Sherwood water pump. I was reminded again of what a terrible design that is. I don't change the impeller often enough as I dislike that job. The impeller had last been changed 200 hours and three+ years ago. The old impeller looked fine upon removal, but I must admit that the engine pumped better with the new one in place.

Two questions:
1. What is the appropriate replacement interval for the impeller, i.e. How often should it be changed?
2. Has anyone upgraded to the Oberdorfer pump retrofit available from Catalina Direct? http://www.catalinadirect.com/index.cfm ... ngines.cfm
If so, please let me know of your experience. I'm thinking that next time I may just upgrade the pump since it appears the impeller is much more accessible.

Thank you for your thoughts

David Edgell
S/v Blue Wing
C350 #442

[wcconway]

Our mechanic upgraded to the Oberdorfer. It's has worked great. No issues. I have pics, but it won't let me upload from my iPad. If you would like pics let me know and I can email.

[KenKrawford]

This was discussed recently on the C34 message board and also has a link to the C36 board - http://c34.org/bbs/index.php/topic,9410.0.html

[C350ia]

Th eOberdorfer M202N 908 is the best way to go. Oferdorfer redesigned the unit just for the M35B and is works like a charm with removing and replacing the impeller from the front, just 4 screws and a snap ring pliers. Try this link for a discount.

Mike Cronin
#314 FlagShip

[C350ia]

Here's the link https://www.marinepartssource.com/newde ... .N202M-908

[KenKrawford]

Mike I think the Orberdorfer part number you want is N202M-15. (M & N were transposed in your original post).

[C350ia]

Yes Ken, I got the M and N reversed. I checked my invoice and I ordered the N202M-908. In conversation with Oferdorfer, if you want to get brass "L-brackets" or hold downs, order N202M-837 which is both the pump and L-brackets.

[dedgell]

Thank you all for your comments and advice. I'll probably go ahead and change the pump out next year as I'm commissioning, or before if the Sherwood starts leaking.

David Edgell
S/v Blue Wing
C350 #442

[Chuck_on_Hudson]

Question about this Oberdorfer pump...is it 100% compatible with the M35 engine, or does the base of the pump need to be modified as described on the Catalina Direct website and the C34 forum?

http://www.c34.org/wiki/index.php?title ... Oberdorfer

A few years ago, I believe that if you bought the Oberdorfer pump, you have to machine away part of the base so it would fit on the engine block correctly because that pump was not specifically made for the Catalina 350 engine. Has Oberdorfer created a new model with the base 100% compatible with the OEM Sherwood?

Thanks,

Chuck

[C350ia]

The Oferdorfer N202M-908 is the model redesigned by Oferdorfer as a direct replacement for the Sherwood. Good Luck

[zman18]

Can I just confirm that the Oferdorfer N202M-908 can be used on the M35B with out any modifications? If so any suggested sources for purchase.
Thanks
John
Hull # 484

[JohnNorton]

Sounds like you have something on your prop/prop shaft hitting the hull. I'd dive in and take a look.