Oberdorfer impeller change

Aug 28, 2015
190
Oday 28 St Joseph, MI
In the spring of 2017 I replaced the water pump on my Universal 5411 with an Oberdorfer pump. Today in preparing for the new season I replaced the impeller. Pretty straight forward except for the life of me I cannot get that split ring back on which holds the impeller on the shaft. The impeller is all the way in the pump body but the shaft doesn’t stick out far enough to put the split ring back on. Anyone have experience with this?
 
Oct 9, 2008
1,739
Bristol 29.9 Dana Point
You need snap ring pliers.
Mine (different than pic) are great for getting the ring off, but nearly useless for getting it back on. The tool keeps popping out. Important to have the right size.
I found that using a tiny flathead with the pliers works.
Also remove the shaft from the pump while doing this. Giant amount easier.

Edit: I read the other poster's link.
When you pull the impeller, there may be washers on BOTH sides. Make a note to put them back in.
Also, no reason you can't pull the shaft out. It's notched on the other side. When reinstalling, just rotate the shaft till it seats. It can't go back in wrong, otherwise you wouldn't be able to get the cover on over the impeller. Worst case if you can't line it up (I don't see how not) is you'd have to remove the pump and put it back on.
4 bolts.

image.jpeg
 
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May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
Leave it off. Not necessary. They only put it there to keep the shaft with the pump while on suppliers shelf.

Les
 
Aug 28, 2015
190
Oday 28 St Joseph, MI
Thanks for your replies, guys. I’ve read so many threads saying “don’t pull out the shaft” that I didn’t want to create any more work for myself but Skipper’s advice was spot on and Ive accomplished the task. Now all that’s left is to get that screw I dropped under the engine.
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
The don’t pull out the shaft comes from the -7 pump in the Universal M25 ( others??) where universal made a funky 1-2” male-male (or was it F-F) adapter shaft inside the engine. Pulling the shaft can make it hard to get back in with out pulling pump housing if the adapter shifts.

If you have an engine without the adapter - no worries (just make sure there is no raw water in the housing).
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
Or out of the bilge if you remove the pump.
I just can’t see this happening. You would have to be extremely careless and for most pulling the pump is a once a decade occurs to change seals and bearings.

Les
 
Oct 9, 2008
1,739
Bristol 29.9 Dana Point
I just can’t see this happening. You would have to be extremely careless

Les
Me.
I'd forget that the shaft is loose in there. And, the only place Neptune would allow my pump to be, as my hand cocked it just right to allow the shaft to slide out, would be over the bilge or over the ocean.
Or, you could be a subsequent owner or mechanic, expecting engine integrity and not knowing that some knucklehead PO removed the retainer.
Aaannd....
Ping! Into the deep sump.
Or, poink! Into the harbor. (Worse. Much, worse. :-D)
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
Well this knuckle head talked to the factory. As the engineer in me didn’t see the purpose.

Les
 
Oct 9, 2008
1,739
Bristol 29.9 Dana Point
Well this knuckle head talked to the factory. As the engineer in me didn’t see the purpose.

Les
Yet you see the purpose of keeping it in the pump on the dealer shelf....

Parts dropping out of things unexpectedly is not good. Especially valuable, mission-critical parts.

In a single boat/owner/maintainer world with a sharp captain, I agree not needed.

BTW, the term "knucklehead" was applied loosely, as in that's what a subsequent owner or mechanic would say, when their pump shaft flies out.
:-D