Re: [OMC-Boats] OMC-Boats Digest, Vol 52, Issue 3

From: Ethan Brodsky <brodskye@...>
Date: Mon, 19 Dec 2011 00:07:56 -0600 (CST)

On Sun, 18 Dec 2011, tklauber@... wrote:
> I went to my extensive OMG ( oops OMC ) library and figured out that somehow
> you have a post 78 upper housing instead of the correct 1970 version as
> originally installed. That retainer came with the later models. Could a wrong
> match cause a leak? - I know nothing about the later models except what is in
> the manuals. The OMC manual says to use special tool 909075 and a breaker bar
> as you noted. They also say to use loc tite when assembling it so no wonder
> it is a bear to get off. You know you are in for trouble when the repair
> manual says to use a breaker bar. If it were mine I would do my best to get
> back to the original components - maybe someone would trade an earlier model
> housing for yours. I have had the worm gear steering out on my 69 which
> should be like a 70 and it pops out - maybe too easy and consequently the
> redesign. It has the snap ring on the rear and one at the front for the gear.
> It looks like your 3/8 threaded cap is boogered up already. You could drill
> it out and replace components that are damaged or you can leave it for the
> next owner. I can send you OMC service manual data or parts lists but you
> already know what is going on now. I could not find reference to 383544 but
> suspect that is the ID tag on the gear housing cover and that cover is
> probably original to your boat and could be used on any of the gear housings
> for 5 bolt caps and later. Maybe hang on to that. You could trace down the
> part numbers in the unit and maybe figure if only the housing was replaced or
> if other things were also replaced like gears etc. An interesting problem. I
> am sure there are older guys out there that know compatabilities for the
> various years. I would tackle the bearing housing later after figuring what
> to do with the steering gear. Good that you are doing it this winter when you
> got time. I personally am working on the bilge restoration on my 69
> sportsman. Waiting for a warm day to paint the bilge blue. TK

I'd be thrilled to have a post '78 upper gearcase instead of an older one,
but I'm pretty such I'm not so lucky. There's a bunch of other traits that
match up with the pre-73 housings - e.g. the "high profile" bearing housing
(pre-73), the older "press-on" ball gears instead of the splined one
(pre-73), the older style exhaust housing cover (pre-78), the "shorter"
tilt pivot cap (pre-78), etc...

It's been trouble-free since I had it apart to replace the ball gear (in
winter '04-'05, right after I bought the boat), and I've had every single
piece apart (except for the worm gear and bearing housing), so I'm inclined
to keep it. I'm pretty sure there will be no future owner of this boat to
deal with it - I'm planning on running it until it is no longer economical
to repair.

The parts fiche show that the secondary retainer bracket was added in '75.
It looks like they switched from the snap ring to the threaded retainer in
'73, though they still look somewhat different than what I have. I
definitely have the quad ring and backup o-ring seal that came after '78,
but the other parts are earlier.

So I really have no idea what year my outdrive is. The last I rebuild it
('05), one of the dealers I got parts from said the 383544 ID tag number on
the exhaust housing corresponded to a mid-70s unit - I can't recall the
exact year. He was an old-timer and had a list of which tags corresponded
to which years - I haven't found it published anywhere.

Anyway, I'm assuming the failure mode with the snap rings is that the
groove tears out - perhaps a previous owner machined it out and threaded
it? Or maybe OMC switched to the newer design earlier and just didn't note
it in their manual - I've found other parts where that has happened as
well. Or maybe this is a new enough upper gearcase that it has the newer
design and somebody swapped in older shafts and other parts? That makes
the most sense - the bosses for the secondary retainer (the two threaded
holes below the worm gear cavity) couldn't've been added.

The threaded cap with the 3/8" flats got boogered up by me trying to remove
it - it was in pristine shape before I started messing with it. New worm
gear steering retainers are available for pretty cheap (GLM #27990, e.g.
$30 at, but I'm more concerned about
breaking the case itself in an effort to remove it. Fortunately, the
retainer is behind an o-ring (actually an quad ring and a backup o-ring),
so there's no way it can be causing the leak. For now I just put the seals
back (I didn't have the right ones on hand because they don't come with the
pre-73 kit), packed the cavity full with Triple Guard grease, and put it
all back together.

I'm still waiting on a few parts (shims, water pump, plus the seals for the
steering worm gear), but I trial fit everything together tonight after
replacing both shaft seals on the ball gear and all the other o-rings in
the case, held the exhaust housing cover down with a ratchet strap, and
pumped it up to 10 psi. It's down 0.5 psi after about an hour - I'll check
it again in the morning. Hopefully that'll be the steering worm gear seal
or because I didn't seal the water pump bolts as recommended. I need to
way to vacuum test it as well.

Once all the parts show up I'll put it all together properly and report
back. I'm hoping to avoid doing the bearing housing.

I would like to add that OMC Type C oil is amazing and I will should never
again complain about paying $8/qt for it. As long as I had everything
apart I pulled the driveshaft out from my intermediate housing to drain and
check the oil. It's apparently also been leaking, as the oil was quite
milky, and, since there is no drain, this is pretty much the original fluid
from when I rebuilt it in '05, aside from maybe a little bit that I put in
each year when the level was a little low. Even so, there was absolutely
no rust or corrosion on any of the internal components, and the bearings
look and feel pristine. I am super impressed that the oil is able to
protect steel from rusting in the presence of water for so long. I pulled
the ball gear and the seal looked so-so (there was only one, not the
back-to-back seals I think it should have; this was also true for my
outdrive ball gear). I just ordered new seals and fill plug washers.

Any other suggestions for where the intermediate gearcase might be leaking?
I assume that little plug on the steering shaft is a vent for when you
grease the steering drum from the zerk fitting in the engine bay and that
that system is entirely separate from the oil cavity? That would mean the
only possible sources of leaks are the outer seals (which I'm replacing),
the inner seals (which I'd really prefer not to replace, as they look okay
and I don't know how a lot of water would get in from there - it looks like
the water cavity is isolated from the shaft cavity), the o-ring on the
cover plate, or the fill plug washer.

Received on Monday, 19 December 2011

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