[Farmall] Another O-12 project, part 2

farmallgray at aol.com farmallgray at aol.com
Mon Feb 16 06:36:28 PST 2009


Karl,
I bet electrolysis would do a good job of getting those support pieces apart.


Todd Markle
Spring Mills, Pa.


-----Original Message-----
From: Karl Olmstead <kolmstead4 at msn.com>
To: Farmall List <farmall at lists.antique-tractor.com>
Sent: Sun, 15 Feb 2009 10:38 pm
Subject: [Farmall] Another O-12 project, part 2




Warmed up my shop again today and fixed the 'Billized' O-12 crankshaft nose.

Had to remove the front motor mount in order to get access to the crankshaft 
nose.  I put a floor jack with a 4x4 on top of it under the engine oil pan and 
jacked it up slightly, then removed the motor mount.  Took a few pictures of the 
mechanical mess that I found.

I measured a couple of good crankshafts in order to determine where I should cut 
off the welded extension.  The crankshaft originally ended about 0.8" in front 
of the first thread on the crank.  I marked the welded crankshaft, and cut off 
the excess with a Sawzall.  I was afraid I'd run into very hard metal, but it 
was actually quite soft.  I should have cut forward a bit more; maybe as much as 
an eighth of an inch.  I was hoping to just 'kiss' the original end of the 
crankshaft, but I actully left about 1/16" of it attached to the stub I cut off.

Used an angle grinder to clean off the excess weld on the crankshaft nose.  I 
could see the setscrew that holds the pin the hand crank engages, and I could 
see about half of the outline of the pin on each side of the crankshaft.  Ground 
down a screwdriver until it just fit the setscrew slot and was able to get the 
screw started.  Lubed it and ran it in and out for a few minutes until it 
finally came out.  Tried to drive out the pin that the hand crank engages, but 
it was slightly welded into place.  Wound up drilling it out.  Came out nicely, 
leaving a clean hole.  Thank goodness Bill hadn't filled up the hole!

Touched up the crankshaft nose with a file and ran a tap through the 5/16" NC 
setscrew hole.  Cut off a 1.8" piece of 3/8" drill rod and drove it through the 
hole in the crank nose.  Reinstalled and tightened the setscrew.

It's not pretty, but the nose of the crankshaft is back to stock.  I installed 
the hand crank assembly temporarily, and it lines up and engages the crankshaft 
perfectly.

The front motor mount on the -12 series tractors consists of a cast iron basket 
that surrounds the front cran
k pulley, and a forged steel piece that reaches the 
frame rails on each side, into which a sleeve on the cast iron basket slides.  
The basket and the forged piece are usually stuck together.  They certainly are 
on this tractor.  I put the motor mount assembly in my sandblast cabinet and 
cleaned up the joint between the two parts.  Then I put the assembly on my 
workbench and soaked the joint with Kroil.  I'll leave it that way at least 
overnight, hoping that Kroil will work its magic.  As I left the shop tonight, I 
set the assembly on top of my woodstove, hoping that the residual heat would 
speed up the Kroil penetration.

If the penetrating oil doesn't do the job, I'll try heating the outer, forged 
part with the rosebud tip on my torch.  Hopefully it'll expand enough to release 
the inner, cast basket.  Eventually, if all else fails, I'll cut the forged part 
off the cast iron part.  I have many of the forged brackets, but no spare 
castings.  They are broken at least 75% of the time, and I ruined one once 
trying to pry it out of the forging.

When McCormick-Deering engineers designed the motor mount system, they provided 
a way for the frame to twist a bit under loads, without distorting the engine 
casting.  The cast iron sleeve inside the forged steel motor mount bracket 
seemed like a good idea.  Over time, however, the two parts rust and lock 
together.  If the frame then twists under load, the cast iron basket breaks.  So 
I need to free up this connection.

I'm feeling a little better about Bill's O-12 tonight.  I've repaired the worst 
thing he screwed up.  The rest of the problems are pretty standard F-12 / O-12 
fare.  I will need to rebuild a fuel pump and a magneto; I've run through my 
inventory of rebuilt units.

Before too long, I'll have to move the O-12 outside and direct the spray from my 
pressure washer into the water jacket opening in the cylinder head.  Now's the 
ideal time to flush out some of the rust which tends to plug up the cooling 
system.  I'll check the radiator for leak
s and probably dismantle it and reseal 
it.  The bottom radiator tanks on -12 series tractors are almost always packed 
with rust, and frequently rusted through.  Having rebuilt a radiator a few 
months back, I know that the work is tedious but not very difficult.

How far am I away from getting this one running?  Two months, I think.  If I 
were in a big hurry, I could probably  do it in a month, but that would require 
working in the shop every night after I get home from work.  That's tough, 
because it takes about two hours to warm up the shop using my leaky, smokey wood 
stove.  Maybe it's time to fire up the propane heater.  If I position it wisely, 
I can have my workspace warmed up in fifteen minutes or so, while the rest of 
the shop remains cold.

Might be a while before I report in again, depending on progress.  If anyone 
would like pictures, please let me know.  My email address is

kolmstead4ATmsn.com, where the AT gets replaced by an '@'.  I can't get to mail 
sent to my old olmstead at ridgenet.net account.

-karl
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