[Farmall] O-12 chronicle, part 3

olmstead at ridgenet.net olmstead at ridgenet.net
Sat Nov 15 19:45:35 PST 2008


A year or two ago I posted a couple of messages about a running O-12 that
I picked up at the November Tulare, CA swapmeet.  At that time I did quite
a bit of work on it.  Rebuilt the fan, replaced the magneto, flushed and
drained the transmission, dropped the engine oil pan and cleaned it up,
fixed the damaged oil filter mount, changed the oil, dropped and lubed the
front axle and steering parts.  After all that, the tractor still had
serious problems.  The transmission flush reavealed that the countershaft
seals behind the brake drums were shot; both brake covers filled up with
lube.  The radiator kept leaking faster and faster as I exercised the
tractor.

I removed the seat, fenders and transmission cover, but then priorities
shifted and I eventually hauled the O-12 off to my storage shed.

About a month ago, a buddy of mine from northern California emailed me and
said that some movie folks were looking for a 1930 to 1940 vintage tractor
to use in a documentary which was going to be shot at Inyokern airport,
which is only about four miles from where I live.  I emailed the movie
people and asked what they had in mind.  I offered to help them find a
tractor, and invited them to take a look at what I had.  As it turns out,
the documentary is about an amazing German WWII aircraft, a flying wing,
and they really wanted to find a European tractor to pull the mockup that
they had built out of a hanger.  I was able to locate a 1948 Ford airport
tug, but they weren't very interested.  I sent them pictures of the 1934
F-20 that I bought from Bob Currie, but I warned them that tricycle
tractors were never very popular in Europe.  Anyway, they dropped by and
really liked my '36 O-12.

They like it because it is small and low, like an airport tug should be. 
And it is extremely nondescript.  Lots of 'patina' and no paint or decals.
 It'll be nearly invisible compared to their airplane.  Especially since
they plan to shoot at night sometime in December.  They can arrange the
lighting to focus attention on their subject.

That meant that I had to fix up the tractor.  It started right up, despite
at least a year of inattention.  But when I filled the radiator, it
sprayed water like a sprinkler.  No hope there.  It was a significant leak
when I put it in the shed; now it was a geyser.  And I found a half inch
diameter rust hole in the bottom tank.

I came up with a plan and waded in.  Removed the tractor's wheels and
tires, which are extremely heavy.  That cleared the way for brake drum
removal and cleanup of the grease-soaked shoes.  I had countershaft seals
on hand, but the -12 series have a goofy countershaft arrangement. 
McCormick-Deering splined the countershafts for the brake drums, but the
splines were too long, no way the seal would work, so they slipped a
bushing over the splines, and that is what the seal slides against.  It
kinda works, but there is a leakage path between the countershaft and the
bushing.  It's just a loose metal to metal fit.  I squirted some RTV
between the shaft and bushing, hoping that it will stop leakage.  I'll
eventually find out whether or not that worked; I'll need to dismantle the
brakes again before long; the old linings need replacement, and the new
ones didn't come in until yesterday.

Re-installed the old brake shoes, drums and covers, and put the wheels
back on.  Cleaned up the fender mounting holes on the axles and installed
the fenders.  Cleaned up the transmission cover mating surface and the
transaxle, dumped in some GL-1, and bolted the cover back into place. 
Installed the side hinged seat bracket and scrounged up a better seat from
my parts tractors.  That pretty much completed work on the rear of the
tractor.

Pulled the radiator and set it aside.  Hauled another O-12 down from
storage and removed its' radiator.  It had better looking tanks and core. 
Dismantled that radiator and began cleanup.  I hate old tractor radiators.
 Since nobody used antifreeze and the bottom tanks are always wet, they
rust like crazy.  I usually find the bottom tanks FULL of rust.  Put on my
ear protection, face shield, dust mask, apron and gloves, and cleaned up
the tanks with a needle scaler.  Then sandblasted the tank flanges and
took a pass with my milling machine to try and flatten out the flanges. 
That revealed considerable warpage and pitting, so I used JB Weld and PC-7
to build up the flange surfaces until the mill made a nice smooth surface.
 Did basically the same to the various inlet and outlet fittings, but
cleaned up the mating surfaces using a disc grinder instead of the mill.

Began radiator reassembly yesterday and completed it today.  Didn't get
the new gaskets in time, so I used RTV sealant in place of gaskets.  Will
check for water tightness tomorrow.  The core is an unknown; I cleaned it
up several years ago, but it has never been tested.  I hope it doesn't
leak!

I think I fixed the massive oil leak from the filter cover.  I was getting
very high oil pressure readings, so I clipped a couple of turns from the
regulator spring.  Pressure's still high, but maybe not off scale any
more.  Won't know for sure until I can fill the radiator and run the
engine longer.  I suppose it is possible that I have a blockage downstream
from the oil pump, but I haven't heard any knocking.  May tap into the
main oil galley and try and learn more.

I still have about a month before the tractor is needed for the
documentary, so I should have it ready in time.  No real surprises; I knew
that the tractor needed a lot of work to make it usable; that's why it got
stored.  I wasn't wrong.  And I wasn't motivated enough to take on the
project until somebody else needed the tractor.

What made this whole process unusual is that I had to keep 'patina
preservation' in mind.  No sandblasting of visible surfaces, no priming
and painting, etc.  In fact, in the places where I was forced to use new
fasteners, I'll probably have to spray paint the new stuff with red oxide
primer.

If this one works out as well as I hope, it could become one of my
favorite tractors.  For some reason, I like antique tractors that are
still in their original condition best.  But they need to run well and not
leak too badly.  If nothing else, they are much easier to work on than a
nicely painted tractor; no worrry about damaging the paint.

I'll let you know how it works out.  I'll probably ask an unemployed
friend of mine drive the tractor for the documentary.  Don't see myself
working outside until midnight some December night, and he can use the
money.  I don't need to be in a movie.  Ever.

-Karl




More information about the AT mailing list