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Anyone have a photo of, dimensions, or an actual part #303894
called a “Retainer” in the photo below?I thought I was missing the (original style) carbon seal spring on this project,
and ran across the Johnson Service Bulletin “Carbon Seal Upgrade”
for the TN28. I read where later models used the same carbon seal as
the upgrade bulletin, hence I ordered a used carbon seal assembly
from a 1957 Evinrude 7.5 hp.It turns out that the only parts in the assembly I ordered that are the same
as the bulletin, are the “carbon seal, spring, and o-ring”.While awaiting the carbon seal assembly to arrive, I thought I’d move the
pressed on collar (on the driveshaft) to the 2-5/8″ position from the top
of the driveshaft, per upgrade instructions. This did not go so well,
and I ended up making a new collar on the lathe.After that, the mail showed up with my used 1957 carbon seal assembly.
As noted, the parts mentioned above are correct, but the “drive shaft
to crankshaft plate” (washer like thingy) for the 57 assembly, does not
work on the TN.
I should have done a little more research, as what I have won’t work
without the missing retainer shown in the Service Bulletin.
I can probably make one, but it would be nice to have an actual photo,
with dimensions, even better!It appears that the original carbon seal actual rode of the bottom of the
rotating crankshaft. Is this correct?
It appears that the upgraded carbon seal does not come in contact with
the rotating crankshaft end, but rather the missing retainer.It also appears that the original assembly was totally worthless as far as keeping water of
of the crankshaft splines, as there’s a big gap between the carbon seal
ID and driveshaft. The TN parts manual does not suggest that I’m
missing any of the original parts.
I’d like to make the upgrade work, as the original setup evidently
wasn’t too good, hence the upgrade bulletin.
Thanks for any help.
Prepare to be boarded!
P.S.- Needed retainer above shows up on Marine Engine as S.O.L.,
and I don’t find one on EBay either.Photo to show just how sloppy the original carbon seal is around
the driveshaft. I don’t understand how it would keep any water
away from the driveshaft splines, but I have to say, the splines
were not rusty or stuck at all when it was taken apart.Perhaps I’m not understanding something?
Prepare to be boarded!
This is what the retainer I’m missing, actually looks like.
I guess I can calculate the total height of the piece, as I know
it needs to compress the spring so the carbon seal’s o-ring
is below the crankshaft splines.What I’m wondering is, should the OD of this retainer be
a snug fit in the LU housing, or free floating.
If it’s “free floating” in the housing, then the top of the retainer
will come in contact with the bottom of the spinning crankshaft.
The “upgrade diagram” in the previous post above, is showing
a “gap” between the retainer and bottom of the crankshaft, making
me think the retainer fits snuggly in the bore.Thoughts?
Prepare to be boarded!
Dan, sorry for the confusion. The photos were showing the old, original carbon
seal assembly, and I was wondering how it could have ever worked.My problem is coming up or making a retainer like shown in the TN28 “upgrade” sheet,
so the new style spring, and carbon seal (from a 57 Evinrude) work in the TN.This photo shows the new parts on my TN driveshaft, and that the “plate” and gasket
from the Evinrude, do not fit my TN’s housing.
Prepare to be boarded!
I found this photo online of an original TN27 Carbon Seal Assembly
in the housing. The carbon seal mates up against the rotating end
of the crankshaft. While it may keep water from getting into
the crankcase bottom bushing, it would not keep water out
of the driveshaft / crankshaft splines, as the hole in the center
of the carbon seal is much bigger than the driveshaft.
There is an o-ring on the OD of the carbon seal, but
not on the ID of the carbon seal, like later seals had.
I presume this is why Johnson put out the service bulletin
for upgrading the seal assembly.
Prepare to be boarded!
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