1952 Johnson 25HP (RD-13) crank seal?

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jpatti75
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1952 Johnson 25HP (RD-13) crank seal?

Postby jpatti75 » Fri Jun 08, 2018 5:56 pm

Started working on a nice RD-13 that has been sitting in the shop for a number of years. While going over the ignition (another non-runner reported to be a runner) and finding a dead coil, I noticed the whole armature plate and ignition components are very oily, and lots of it is already gummed up. I assume this points to a faulty top crankshaft seal, but this one has a different seal than I am used to. I removed the spring and retaining washer under the ignition cam. Is it possible to pull the seal, or do I need to split the crank case open to get it out? This may be a dumb question, but is there an option to replace that upper retainer washer under the spring with a lip seal?

It’s all a big oily mess right now, so I am hoping this repair is easier than it looks.

Thanks,
JP
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FrankR
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Re: 1952 Johnson 25HP (RD-13) crank seal?

Postby FrankR » Fri Jun 08, 2018 6:56 pm

There is a carbon seal under the spring and washer. Simply lift it out. There is an o-ring inside it, so it will have some resistance to sliding up the shaft. Careful, it is fragile. Maybe already broken (causing the leak).

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jpatti75
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Re: 1952 Johnson 25HP (RD-13) crank seal?

Postby jpatti75 » Fri Jun 08, 2018 8:31 pm

Thanks, Frank! I’ll be heading down to the shop momentarily to give it a look and start the clean-up process.

Changing gears a bit, I noticed the recoil pawls have scraped the top of the flywheel ever so slightly. The recoil itself seems to be working as it should, so do I possibly need to shim it up ever so slightly with some washers?

Man, these motors sure give your shoulder a work out trying to start them.

JP
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david bartlett
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Re: 1952 Johnson 25HP (RD-13) crank seal?

Postby david bartlett » Fri Jun 08, 2018 8:35 pm

jpatti75 wrote:When properly tuned, they start great. Mine starts in 2 pulls cold, and one pull all day after that! The old style recoil doesn't give much mechanical advantage though.



Man, these motors sure give your shoulder a work out trying to start them.

JP
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Re: 1952 Johnson 25HP (RD-13) crank seal?

Postby Chris_P » Fri Jun 08, 2018 9:20 pm

Check for bearing wear. Try to move your flywheel fore and aft. Perhaps top bearing is shot, causing seal failure, and rubbing of the recoil.

Hopefully not.

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Re: 1952 Johnson 25HP (RD-13) crank seal?

Postby jpatti75 » Fri Jun 08, 2018 11:02 pm

Thanks for the tips, guys!

Although, I’ll try again tomorrow, I did try to move the crankshaft fore to aft, and didn’t notice any play. Maybe the previous owner didn’t have the flywheel torqued down to spec?

The o-ring in the carbon seal was a little brittle, so hopefully replacing it solves the issue (fingers crossed). Could someone confirm that the part number for that o-ring is 302540?

Got all of the oil and dried up old grease off the armature plate tonight and dug up a good coil to replace the dead one. Going to give the condensers a test, too. Hopefully when I get the new o-ring and get everything back together I’ll be able to report that it starts in two pulls like Dave’s!

JP
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david bartlett
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Re: 1952 Johnson 25HP (RD-13) crank seal?

Postby david bartlett » Fri Jun 08, 2018 11:15 pm

302540 is the correct part #. If you want, I have some Quad rings for these I can give you. I have several. PM me with your address and I will send them to you.
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jpatti75
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Re: 1952 Johnson 25HP (RD-13) crank seal?

Postby jpatti75 » Fri Jun 08, 2018 11:23 pm

PM sent, David. Thank you very much!
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jpatti75
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Re: 1952 Johnson 25HP (RD-13) crank seal?

Postby jpatti75 » Tue Jun 12, 2018 7:08 pm

Is the o-ring installed “dry” or should I use some non-hardening sealant on it?

Thanks,
JP
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FrankR
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Re: 1952 Johnson 25HP (RD-13) crank seal?

Postby FrankR » Tue Jun 12, 2018 8:13 pm

Oil or Vaseline


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