PO-15 Lower Unit questions

[Buccaneer]

I took the gear box apart today (bottom half) on the PO-15.
The prop shaft has an extra hole in it that seems to have
no use. This 1/8" hole has a pin in it, but is flush with the
shaft. This hole would ride inside the prop hub bore.
Any ideas what it’s for?

Also, the prop shaft outboard bushing has been modified
(perhaps as mentioned in the Johnson repair manual)
to accept a modern seal, to replace the cup with leather washer.
It appears the seal number is…..
CR 301991, but it’s hard to read.
That number does come up on Marine Engine as a seal,
but of course it gives no size or application.

I did not pull the seal yet, but the bore is about 1.400 inches,
and the shaft size is .875

The Johnson repair manual doesn’t say what seal number is used
in the modification, but then again, the modification may
not have been done by a OMC tech!

Has anyone run across the CR 301991 seal in their PO-15 prop shaft,
or can verify the dimensions of this seal?
Thanks!

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Prepare to be boarded!

[dan-in-tn]

#301991 is a retainer according to my 1970 parts price book. ME does show it as a seal. If you decide to buy an after market seal try for a stainless steel case as steel won’t last long! I did not find anything that matches up in the Sierra catalog unless you want to make a sleeve to reduce the outside diameter. They make a seal #18-2026 .875 X 1.250 X .188 wide. I think you have a lathe so a sleeve would be one way to go. That Sierra seal $9.76 is more than the proper number seal. $9.00 isn’t too bad for a seal?

Dan in TN

[Buccaneer]

Dan, Thanks for the reply. The seal that’s in it is a brass case, very sturdy
looking, and probably 5/16" thick. The SKF seal look-up has some
that are close to what I need. I probably need to pop the old seal out
to get a better OD measurement.
The $9 ME seal would be okay, just want to make sure that’s actually
what I need. I haven’t tore into the drive shaft housing yet, but I
don’t think that even has a seal.
Hope you’re not near all the fires down there!
Thanks!

Prepare to be boarded!

[Buccaneer]

I popped the lower driveshaft out of the housing today.
No drive shaft seal for sure, but in looking at it,
there’s never water in the drive shaft housing… unless
a gasket or prop shaft seal leaks.. so no seal needed.

I also popped the prop shaft seal out of the gear case today
and got an accurate measurement on the diameter, which is
1.375 OD. Looks like the bore will take a seal 3/8" thick.

Prepare to be boarded!

[Author]

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