Sub_12_restoration

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.

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Those two pieces of the key on my melanin-free hand are only supposed to be one piece.

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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.

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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.

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Not a happy ending to this one....all this tractor stuff was sold during divorce liquidation in April 2002.

Vintage Sears Garden Tractors