Home › Forum › Ask A Member › 1929 Johnson Model J-25 Plug Wire
- This topic has 15 replies, 4 voices, and was last updated 3 years, 7 months ago by
Tubs.
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May 4, 2022 at 8:31 am #259401

I can take a pump apart an to get you piston
dimensions if you are planning to make a new one.
Tubs.A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.
May 4, 2022 at 8:51 am #259402
I can take a pump apart an to get you piston
dimensions if you are planning to make a new one.
Tubs.Thanks Tubs, I’ll clean it up today and see what the diameter of
the piston is, and perhaps estimate how much of the length is
missing, and if I need more info., I’ll let you know.
The real question is, “what” I’m going to find to make a new piston?
I presume that I’d need to silver solder some “hard facing” of some kind, on the
end that rides on the cam.Prepare to be boarded!
May 4, 2022 at 8:58 am #259404
I don’t think there was a hard facing on the piston.
The piston is sacrificed to persevere the cam on
the prop shaft gear.
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A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.
May 4, 2022 at 10:33 am #259406Also consider the surface of the cam. No sense in rebuilding the piston if a corroded cam will just chew it away. See this discussion https://www.aomci.org/forums/topic/early-johnson-plunger-for-pump/
May 4, 2022 at 12:31 pm #259407Thanks for the replies. Regarding “hard surfacing”, maybe I was thinking about
the photo I seen once of someone soldering a nickel onto the piston!
I decided to reuse the piston, as it was just the one end buggered up.
I made a stepped brass end where about 1/8″ inch presses into (and soldered)
the good end of the piston, and another 1/8″ sticks out beyond the end of the
piston, that rides on the cam.
That’s all the longer I could make brass end, and still have clearance without
bottoming out. I suppose one could shorten the piston in order to have a thicker
brass “wear end”, but this should last quite a while, and forever, if I don’t get
it running!
My real thought of the day, how long was this motor ran with that big hole
in the water pump piston? I can’t see how it possibly pumped any water?
Photos this evening, I hope.Prepare to be boarded!
May 5, 2022 at 11:13 am #259443 -
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