Prop Shaft Seal Replacement on 1974 OMC 25 HP

[h20lew]

So I have disassembled a gearcase from a 1974 Evinrude 25 HP.  I have the Sierra kit and included in it is a prop shaft seal.  I’ve done that seal replacement on 35 HP motors where there are two holes in the face that is facing the prop – but there are no such holes on this one.  I can see the seal behind the face. The factory manual makes no mention of replacing this seal.  Marine Engine gives a part number for the replacement seal which looks like the one in my kit – so it sounds from them that it should be replaceable. My question is – what is the recommended procedure to remove the end face and replace the seal?

[bobw]

You can usually remove that cap piece at the back of the gearhead by inserting a small punch through the front end of the gearhead and tapping the cap piece out the back.   Then you can access the seal for removal and replacement.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[fleetwin]

Unfortunately, it looks like that seal and cover came originally as one piece from OMC:

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1974&hp=25&model=25402M&manufacturer=Evinrude&section=GEARCASE

I suppose you could try to knock that SS cover/shield out of there, and replace the seal.  I’m not sure if I would reinstall the SS cover though, it might come loose back there and flop around causing damage…

[bobw]

I’ve had a few motors with that rear cap or cover and have always found them to be a separate piece that can be removed.   Here’s one I recently removed to replace the propshaft seal.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[frankr]

Agreed, that piece pops out and back in. It is a fish line excluder. It might not even be needed with the new seal pictured above, which supposedly keeps the fish line out by the same close fit. Worst case scenario is even without the excluder, it will be no worse off than the older motors that didn’t have the feature at all.

[h20lew]

Thanks guys – wasn’t sure if it was threaded or not and didn’t want to pound on it without confirming. Popped right out just like you said.

[fleetwin]

Cool!

[Author]

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