This 1969 Suburban 12  looks like it was stored inside earlier in its life. The paint is in pretty good condition. All the little parts, like the
belt guard, front frame cover, and starter belt cover are there. The front grille near the headlights is broken. Also, the connecting rod is
history. The crank will spin most of the way around, until a solid "thunk" can be heard. Plus, the piston does not move when spinning
the crank. The story about the final minutes of the tractor's operation was that the owner was mowing, when the engine "started
making noise, then just stopped". The tractor sat where it stopped, until rescued by a concerned Sears collector. Let's take this one
apart and restore it!
What happened to the connecting rod?
I always like trying to figure out a mystery, (after all, I am a cop) so I spent a little extra time playing around with this engine to see
what happened to it. I really didn't have to, because I have another 12 hp Tecumseh with low hours just waiting to be painted and
bolted on. Something I liked about this tractor is that it came with the original type, oval muffler with the exhaust openings in both ends.
The first thing I did was to remove the muffler for transplant onto the other engine. I couldn't help but notice that something was
rattling around inside the muffler, so I shook it around and guess what came out?  Several small screws used to hold the throttle plate
onto the throttle shaft.
OK, so if the screws that hold the throttle plate on are in the muffler, then what's holding the
throttle plate on?  Better check the carb to find out. Surprise, surprise! The throttle plate is
missing!  Plus, the choke plate is about to get sucked into the engine too, as it is only being
held on by one loose screw. I didn't have to look too far to find the throttle plate; it was
stuck in the intake port. It had been floating around in there for a little while too, judging by
the way it got hammered by the valve. HOW COULD THIS ENGINE RUN WITHOUT
THE THROTTLE PLATE???  If anyone has any ideas, let me know. I would later find
that there were two other screws under the cylinder head. One was pushed into the soft
aluminum material. I had to back it out to remove it. All right, so now I have five screws
floating around inside this engine, but only three are missing from the carb. The only thing I
can figure is that two (or more) came loose previously and were replaced. The moral of the
story is to make sure your screws are tight. Use Loctite, or other thread locking solution to
keep them where they belong.
Well, the throttle thing had me a little stumped. Let's move on. The next thing was the
blower housing. After taking the belt guard off, I noticed that the screen that should be on
the flywheel was missing. Shiny, new bolts were holding the starter belt pulley onto the
flywheel, but the screen was nowhere to be found. Not good news if the tractor was being
used  to mow with. The screens are there to keep clippings and other things from getting
sucked into the cooling system. Don't forget that these engines are cooled by massive
amounts of air passing over the cooling fins. If you have any doubt about how much air is
forced through the engine, hold your hand about two feet from the right side of the engine as
it is running at full speed. Anyway, when I finally got the blower housing off, it was obvious
that this engine could not have been cooled effectively. There was all kinds of debris
blocking the path of the cooling air. I thought at first maybe a mouse had made a nest in
there, but as I picked through it I found it was just junk that would have been blocked by the
screen if it were there. I'm sure this engine was overheating in its final minutes of operation.
click photo to enlarge
click photo to enlarge
click photo to enlarge
click photo to enlarge
Those two pieces of the key
on my melanin-free hand are
only supposed to be one
click photo to enlarge
Onto the flywheel...It came off with minimal effort (and a large puller). Of course the key
was sheared. Any time the engine comes to an abrupt stop, as this engine obviously did,
the key will shear. This is intended to keep the kinetic energy of the flywheel from
twisting the crankshaft. It's the sacrificial lamb, so to speak. No problem here, they are
cheap to replace. Now that the engine is nearing a stage where I can remove it from the
frame, I thought I would drain the oil so it didn't leak all over the floor of the garage when
I tipped the engine. Here's the biggest surprise...THE ENGINE HAD NO OIL!  What you
see in the bottom of the coffee can on the right is all the oil that was in the engine. So on
top of the fact that the engine ate at least five screws and had no way to cool itself, it also
had no refined dinosaur in the crankcase! No wonder it was in self-destruct mode. How
many of us get new equipment and look at the first couple of pages of the manual where it
has all the generic "warning" and "caution" statements, and chuckle to ourselves about the
rudimentary statements made by the writer. "Make sure the oil level is within acceptable
range", is a common sentence.  Gimme a break, I've often thought to myself, who would
operate an engine without checking the oil??? I guess the previous owner of this tractor
did. He also didn't change it often, judging by its jet-black color. With any luck, I'll just get
away with an overbore, piston/rings and a new connecting rod when I decide to rebuild
this engine. I'm not optimistic though. I suspect that the crank and cam will be just a
scored as the cylinder walls.
click photo to enlarge
2/22/2001, I finally got the time to tear down the engine all the way. The rod is a sad
sight. I don't know if the crank can be used again either, as there is a considerable
amount of metal tear-out. The skirt on the piston is broken where the rod hit it. The
valve gears seems to have survived the oil free operation unharmed. The bore is within
acceptable range. There is a little scoring where the piston skirt dug in. It will clean up.
I bet this thing sounded like the hammers of hell just before it "quit."  I'll never
understand how someone can do this to a perfectly good piece of equipment.
click photo to enlarge
click photo to enlarge
All material © 2000 VSGT
Not a happy ending to this one....all this tractor stuff was sold during divorce liquidation in
April 2002.
Vintage Sears Garden Tractors