Time for a new crankshaft seal?

[opposedtwin]

There is oil residue here under the mag but i did lubrcate the retaining ring and the support when i rebuilt this magneto about 6 years ago. There is also some residue on the mag plate, but i have seen worse.
So i guess it’s worth changing since i’ve come this far, huh? How long should a crank seal last?
Thanks,
Scott

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[Mumbles]

If the motor has the original seal in it, it’s done its job and should be replaced. You can confirm if the seal is leaking or not by pouring a bit of oil or fuel mix over it and slowly crank the motor over. Any bubbles or disappearing oil means you have your work cut out.

Here’s a short video of a leaky seal

https://www.youtube.com/watch?v=cXt6fV6Z5rc

[chris-p]

For the time it takes, literally 30 seconds, and the price, I would change it. Any motor I restore gets new crank seals regardless.

Another thing is to ensure you are using the correct grease on the mag plate. To thin a grease will get thrown off and foul the points. Just a thin smear is all you need.

[frankr]

quote Chris_P:

For the time it takes, literally 30 seconds, and the price, I would change it. Any motor I restore gets new crank seals regardless.

Another thing is to ensure you are using the correct grease on the mag plate. To thin a grease will get thrown off and foul the points. Just a thin smear is all you need.

And that does look like grease on those points.

[garry-in-michigan]

Many outboards bleed off the surplus oil through a passage to the intake manifold. if your model has one, be sure it is not blocked. . . . 😉

[opposedtwin]

Garry, this is a johnson FD-11. Have you got a picture of this passage you could post?

Just found a seal in my new parts bin (woo hoo!) so i removed old and installed new. That’s two in the last month with my new tool i got from Richard! THANKS!!

Will clean up magneto, reassemble and hopefully i’m back on the water tomorrow!

Thanks guys!
Scott

[fleetwin]

I’m guessing this is one of the engines with the goofy oil return system and no oring around the upper bearing….If so, be sure the hole leading down into the intake manifold is clear…

[chris-p]

Scott,

Just so you know, this is not something that you can check with the motor all assembled. Just don’t want you to waste time looking for this! When the crank halves are separated, you can see the oil return hole in a groove in the crank case casting. It is pretty small. I don’t think I have ever found that passage blocked, but I guess it could happen. I have seen some guys install an o ring on the top bearing by mistake…..that could/would block the hole. Especially if they added sealer to the o ring. The intake manifold creates a siphon effect, that draws the oil/fuel mixture from the top of the crank, back down to the intake to be re used by the motor. That, in conjunction with the top seal, prevents fuel/oil mix from exiting the block onto your mag plate.

[fleetwin]

The only clue to its presence I have seen is a slight cut out in the housing just about the bearing toward the intake manifold…

[opposedtwin]

Ok, i guess i won’t worry about it??

Is this a good grease to use on the support and retaining ring?

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