Topic: Lower Unit Gear Lube Rule of Thumb? – Antique Outboard Motor Club,Inc

This topic has 11 replies, 8 voices, and was last updated 9 years, 6 months ago by The Boat House.

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May 18, 2015 at 11:01 pm #1533
Buccaneer
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US Member
From the Scott Atwater manual, outboards under 10 hp use grease
in the lower unit, and the rest use hypoid oil. Therefore, I assume
my 1950 Firestone 5 hp originally used grease.
The Firestone is fully jeweled, so would hypoid gear lube be better,
if it will stay in the lower unit?
Thanks, Bucc

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May 18, 2015 at 11:02 pm #16384
RICHARD A. WHITE
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Lifetime Member
The jeweling may refer only to the power head….

http://www.richardsoutboardtools.com
classicomctools@gmail.com
May 18, 2015 at 11:20 pm #16385
The Boat House
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- This reply was modified 6 years ago by The Boat House.
- This reply was modified 3 years, 9 months ago by The Boat House.
May 19, 2015 at 2:02 am #16403
Buccaneer
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"Jeweling" was my terminolgy, not the manual’s,
but perhaps not a correct one.
Three needle bearings, one ball bearing, and I guess
there is one bushing in the lower unit as well.
It had a prop seal, and now has a seal on the drive shaft,
so I guess I could try the hypoid and see if it leaks out!

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May 19, 2015 at 2:05 am #16404
frankr
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1950 would use grease. Oil will leak out.
May 19, 2015 at 1:38 pm #16434
Buccaneer
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I wonder what was different about the 10 hp Scotts that used hypoid oil,
that had the similar looking lower units? The big gear cover on the
leading edge of the L.U. does look prone to leaks.

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May 19, 2015 at 4:29 pm #16450
jeff-register
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US Member - 2 Years
Buc,
The front cover you speak of will leak. It’s weak point is the three screw threaded holes pull out a few thousands. Use a straight edge along the mating surface to see how flat it really is. Use little plumbing washers under the three screws as well. Another leaking point is the aluminum shift tube inside the case. Remove the tube & replace the O-ring inside the pipe & replace. I had a member machine the gearcase so I could install two drive shaft seals, one up & other down to stop the driveshaft from leaking. You will find the drive shaft has pits in it. I have used JB weld to fill it in a little. Not perfect but better. I need a torch to fill it in pits with brass. The propshaft needs a seal too but replace all it’s bearings too. There is a needle right above the pinion gear too. I fill my motors with 105. It is thin enough to lube the needle bearings. Fill from the bottom up.I use a short piece of blood pressure tubing on the shift shaft rod & on to the aluminum tube to seal that guy double too.
Jeff
May 19, 2015 at 4:31 pm #16451
Mumbles
Participant
If the gearcase has seals on the shafts, I’d go with the oil. Gear oil is the desired lubricant over grease in any gearcase which can be sealed up. If I can do some machining and adapt seals to my antique grease style cases, I do it and run OMC/BRP HI-Vis or Mercury Hi Performance synthetic in them.
May 19, 2015 at 9:00 pm #16469
legendre
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So how is the grease introduced, pump it in with a gun and special fitting?
May 20, 2015 at 12:49 am #16491
Buccaneer
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US Member
Guess I’m not out much trying the oil…… if it leaks out, then grease it is!
The L.U. has all new needle bearings, new prop seal, and I shortened
the drive shaft bushing 1/8" so I could install a seal there as well.
And thanks to your advice before Jeff, I installed a new o-ring on the
shift rod, as well as put a new piece of tubing on the shift rod guide tube.
I hope the thing shifts when it’s running, as it seems impossible while not…..
but I didn’t try too hard so as not to break!
Regarding the Lubriplate 105 grease….. mine is in a tube……. insert
and squeeze….. I guess.

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