Changing Impeller Oberdorfer Pump N202M-908

Apr 17, 2013
153
Catalina 310 57 Pompano Beach, FL
Have Hull# 57 Catalina 310 recently switched out the Stock Sherwood pump on the Universal 25XPBC with the Oberdorfer N202M-908. When I did the first impeller change the shaft came out of the pump with the impeller attached. Is this normal? There is a circlip which must be removed to take the impeller off the shaft. It was no problem replacing the impeller then putting the shaft back into the pump, just wondering is that what normally happens.
 
Feb 8, 2014
1,300
Columbia 36 Muskegon
I have an older Oberdorfer on my 5411. Can't figure out what that circlip is supposed to do. The impeller is held on by the pump cover and the shaft can't go any deeper into the housing. It does nothing. It's still there on mine but if I ever lose it I don't think I'll replace it.
If the impeller sticks to the shaft, the shaft will pull out. No problem, just slide it back in. It's actually a lot easier to get the impeller and circlip back on with the shaft out. Just rotate the shaft as you push it back in. At first it won't go all the way in, then the slots will align and it will go the rest of the way.
The older pumps have an adapter between the pump shaft and cam shaft than can require removing the whole pump to get it back in right. I think yours is new enough not to have that. The difference is the end of the shaft. Of it has a female slot, there is an adapter. If its a male tang, no adapter. Mine has the adapter but I have been able to put it back in without removing the pump.
 
Feb 26, 2004
22,759
Catalina 34 224 Maple Bay, BC, Canada
1.......If the impeller sticks to the shaft, the shaft will pull out. No problem, just slide it back in. It's actually a lot easier to get the impeller and circlip back on with the shaft out. Just rotate the shaft as you push it back in. At first it won't go all the way in, then the slots will align and it will go the rest of the way.
2.......The older pumps have an adapter between the pump shaft and cam shaft than can require removing the whole pump to get it back in right. I think yours is new enough not to have that. The difference is the end of the shaft. Of it has a female slot, there is an adapter. If its a male tang, no adapter. Mine has the adapter but I have been able to put it back in without removing the pump.
1......Yes

2.......You'd have to have a really old pump for this to be an issue. Here's why, with pictures of the shaft and the slot inside the engine. I always simply pull the whole shaft/impeller out completely.

Oberdorfer Pump Rebuild 101 - http://c34.org/bbs/index.php/topic,6766.0.html

Good move to trash the Sherwood, since it is, well, trash.

Here's why:

Why SHERWOOD Raw Water Pumps leave a LOT to be desired: http://c34.org/bbs/index.php/topic,8493.msg59876.html#msg59876 Thanks to Ken for that one, I'm tired of repeating it. - Stu 5/25/2015
 
Feb 8, 2014
1,300
Columbia 36 Muskegon
Right. Mines the old one. The manual says if you pull the shaft out you have to remove the pump to get it back in. I've found that not to be true.
 
  • Like
Likes: CaptKathy
Nov 22, 2011
1,192
Ericson 26-2 San Pedro, CA
The circ clip is unnecessary. I ran that pump for years without one. Only purpose I can see is if the pump is off the engine the clip will keep the shaft from sliding out the back.
 
Feb 8, 2014
1,300
Columbia 36 Muskegon
That's what I was thinking. Might have a purpose on some engines, but not a Universal.
 

Clydo

.
May 28, 2013
336
Catalina C310 SF Bay/Delta
The circ clip is unnecessary. I ran that pump for years without one. Only purpose I can see is if the pump is off the engine the clip will keep the shaft from sliding out the back.
Same here. Removed circ clip off my C30 M25 and ran over five years with no problem at all. Other members
on list did the same thing. Much easier to replace impeller.

Clyde Thorington
C310 @ 245
ILEAN TOO
San Jose, CA
 
Mar 8, 2016
3
Catalina Catalina 36 Bellingham, WA
Thanks for the info on the Oberdorfer pump. I have N202M-15 on my Universal. I nearly had a heart attack when the shaft came out during the impeller replacement job. I thought there would be bearings rolling around in the pump and I was going to have to take the whole pump apart .... Glad to know about the circlip, too; it didn't seem like the impeller could go anywhere. And the diagram I have since found on the Oberdorfer specs shows that the paper gasket is unnecessary, too.
 
Jul 7, 2023
3
Cal 2-27 Seattle
Hey all - I’m trying to replace the impeller on my Oberdorfer (the late one with the male shaft end). I’ve removed that little caliper but the impeller still won’t come off. It moves around on there just fine so it does not seem like a corrosion issue, just stuck on the end. Any ideas?
 

Attachments