Old Sears Suburban SS12

jwstewar · Apr 4, 2012

I've got Dad's old Sears Suburban SS12. It is in pretty decent shape, even though I used and abused this machine for several years before I bought the NH. I don't remember exactly what happened, but I remember it wouldn't start or something. This was back in 2002. Dad took the tractor back to his house and started doing some trouble shooting on it. I know he had the coil and the mag tested, both were supposedly good. Now here is where it starts getting interesting. Dad then started troubleshooting a bit deeper. He started disassembly things. Apparently between him not feeling well and such maybe he couldn't remember, he didn't put things back together, but he would take more apart. Well, as part of my commitments to him before he passed, I said I would get his baby running again - already have fixed a couple of his other items including his snowblower and his "new" Snapper riding lawn mower that I bought him in 1997.

Anyway, this is where we are today. I've got the tractor at home in the barn and I think I have most of the parts.

But in his disassembly he disconnected probably the only safety switch on the darn thing. I put new ends on the wire on the actual safety switch and plugged the wires back in to it, but I've got two other problems. I can't find where the other end of the wire is supposed to plug in. I'm assuming when the switch is depressed it is supposed to complete the starting circuit, but without knowing where this is, I have no idea if he jump it or not. Second, I can't figure out how the brake/clutch panel is supposed to engage the button.

I've looked on Sears' website for a manual, but the one for the tractor is some little cartoon like drawing, but the one for the plow and the mower deck are much more modern looking and go into much greater detail.

Anyone have any ideas on either of these? I've attached pictures so you can see what/where I'm talking about.

Scotty Dive · Apr 4, 2012

I just sold both my SS12's - 1967 and 70 - neither one had that plug. Can you get me the engine number - it will start with a 143 and be on the left side of the engine shroud and the tractor number located on the shift plate and will start with a 917. I may have a a manual or send you in a good direction...there are some good forums on yahoo for these tractors.

jwstewar · Apr 4, 2012

Thanks Scotty, I will get them as soon as I get home tonight.

Scotty Dive · Apr 4, 2012

I just sold both my SS12's - 1967 and 70 - neither one had that plug. Can you get me the engine number - it will start with a 143 and be on the left side of the engine shroud and the tractor number located on the shft place and will start with a 917. I may have a a manula or send you in a good direction...there are some good forums on yahoo for these tractors.

RandyT · Apr 4, 2012

The first picture would be of the neutral start switch and should be wired into the starting circuit from the key switch to the solenoid or coming off the ground prong of the solenoid if it is a four wire solenoid. the second picture looks like a connector for headlights.

jwstewar · Apr 4, 2012

RANDYT said:
The first picture would be of the neutral start switch and should be wired into the starting circuit from the key switch to the solenoid or coming off the ground prong of the solenoid if it is a four wire solenoid. the second picture looks like a connector for headlights.

It is the other end of the same wire that is coming off the neutral safety switch.

And for Scotty, the Engine Model Number is 143.622022 and Serial Number 2074E. The Model Number of the tractor is 917.25371 and the serial number for the tractor is 3298.

Thanks for everyone's help. Can't wait to hear it run again.

Scotty Dive · Apr 5, 2012

I dont have those exact manuals for a 1972- but this site does have it for the tractor. I can send you an engine manual if you pm me your email:

Sears Manuals

jwstewar · Apr 16, 2012

It was raining here Saturday afternoon so I had a chance to work on this some. Looking at the electrical diagram on Sear's website and the parts diagrams, I think I have this figured out.

Looks like I was right on the brake switch, however there is a little tab held on by a cotter key that is broken off. Who knows where, when, or how, but it is gone. So it won't actually depress that safety switch. Of course, not available. I've sent a msg to a guy on ebay to see if he would have one, no repsonse yet. The second wire I posted looks like it goes to the attachment lever safety switch. Kind of weird on the Sears' diagram, it is inline with the brake safety switch (that makes sense), but it has a circle around it like it was optional. I see nothing on my attachment lever that would correspond to this. Since this tractor didn't originally have a mower deck, would they not have put that safety switch on it and just jumpered the wire? I don't know, but in the short term that is what I'm going to do for both of them.

I also found, that it looks like the ignition switch is bad. I can get continuity through the start circuit, but not on the run circuit. I'm going to stop tonight and pick up a new switch for it. I then found the one wire that goes to the motor from the ignition switch, I thought it was a ground wire, but now it seems to be the hot wire from the ignition for maybe the magneto? It is labeled on the diagram as M. The other 2 wires are B - coming from the battery and S - solenoid. There is then a ground wire with a loop that goes around the threaded portion that sticks through the dash.

jwstewar · Apr 16, 2012

On a different note on this, we went into Mom's yesterday and cut the grass and I loaded up most of Dad's tools into the stock trailer and brought them home. Including all of the link arms for the mower deck for this old Sears, the front/rear weight and bracket, the 3-point disk, and the bracket for the snowblower, as well as all of the parts Dad took off the tractor trying to trouble shoot whatever the original problem was. I still have a few more tools to get and some misc stuff, but the biggies left are his portable table saw, the mower deck for this tractor, the 3-point plow, and the snow blade.

mostly_gas · Apr 17, 2012

On the ignition switch, no continuity may be correct. It seems like a lot of the motors don't use battery power for ignition. If the off position does provide continuity that means it is grounding out the ignition. If you had continuity in the on position then the ignition would not work.

jwstewar · Apr 17, 2012

OK, that makes sense. I will check that when I get home tonight. Thank you, I wasn't able to find a replacement switch last night so this will allow me to get that part of it back in tonight.

jwstewar · Apr 17, 2012

Yeah, got the ignition switch reinstalled tonight. I installed jumper wires in place of the two safety switchs and got the starter turning over with the ignition switch. Now I need to pull the cover back off the engine and hook the "M" wire from the ignition switch to the magneto somewhere. Not sure where that is, but won't know until I pull that cover. I was also able to get the motor turning over a bit tonight. Wasn't necessarily a bad thing to turn the motor over a bit w/o a spark or fuel since it has been sitting so long.

jwstewar · Apr 19, 2012

I stopped last night and picked a battery up for this tractor.
I've also been looking at the manuals and stuff for the engine and tractor that I have found online and folks have sent me. The wire that I thought went to the magneto actually goes to the side of the block (which is where I thought it went originally based on where it was and such). I hooked that wire back up and the battery. No spark. Pulled the plug wire and I can't see where it is trying to jump to the plug.
Not sure where to go at this point. I think I remember Dad telling me he had the magneto tested and it was good, but I can't swear to that. I'm not sure where to from here. I think there is a gap on flywheel that can be adjuster to the mag. Maybe that is what I need to do? Not real sure where to go next. Maybe pull the mag and take it to the local mower shop and have it tested again....

Funny, talking to Mom last night, I guess Dad had mentioned to her that something was broke and he couldn't get one anywhere, but that is OK, he would make one. That was good to hear, even though he was starting to go down hill, he knew what was going on and what he needed to do to fix stuff. That is partially why this tractor was in the shape it was, he still knew how to take it apart, just couldn't remember how to put it all back together.

mostly_gas · Apr 19, 2012

I am guessing with the age of the tractor that you might have points in the ignition circuit. Tr pulling the wire you attached to the block and check spark again. Check coil/flywheel gap. clean the points if you have them.

jwstewar · Apr 23, 2012

I worked on it a bit tonight. I pulled the flywheel and got to looking real close at the pulse transformer. I notice the wire coming from the magneto had been pinched at some time. I pulled it off and cut the end of the wire and soldered a new end on it along with a new connector that went on to the magneto. I then also sanded the magnets and got them clean. I look how to adjust the plate on the flywheel, but when you loosen the screws they just back out without moving the plate. I put it back together being optimistic. Turned the engine over and it didn't try to start. I pulled the plug and ground the edge of it to the engine. I can see a blue spark, just not sure how strong it really should be, but this one was decent. I'm going to stop and get a new plug tomorrow and put some more gas in it and give it a try. I'm also going to look and see how and if they can be to adjust the valves. I'm not sure if this has timing that can be adjusted or not, I don't really see how it can be as it driven off a woodward key in a groove on the crankshaft corresponding to a groove on the flywheel.

5030 · Apr 23, 2012

It's a woodruff key BTW.

Gap the magnets to the coil with a business card between the magnets and the coil assembly. Loosen the bolts holding the coil assembly with the business card between and slide the coil until the business card just slips out and tighten the coil. That's the correct coil to magnet gap.

I'd give the whole thing (tractor) a bath in degreaser and pressure wash it before fiddling with it. I hate greasy grimy stuff to work on.

That's my regimen prior to working on anything used.... clean it first.

jwstewar · Apr 23, 2012

5030 said:
It's a woodruff key BTW.

Gap the magnets to the coil with a business card between the magnets and the coil assembly. Loosen the bolts holding the coil assembly with the business card between and slide the coil until the business card just slips out and tighten the coil. That's the correct coil to magnet gap.

I'd give the whole thing (tractor) a bath in degreaser and pressure wash it before fiddling with it. I hate greasy grimy stuff to work on.

That's my regimen prior to working on anything used.... clean it first.

Thanks on the woodruff, thats what happens when you are yelling at kids while you are trying to post on the internet.

I'm still trying to figure out how adjust this gap. I've attached a picture of the mag, the flywheel then goes over top this and completely covers it, so I'm not sure how to tighten it down. I don't think I could even be able to get a business card behind the flywheel and up to the mag area.

jwstewar · Apr 24, 2012

New plug is in, but still no start. Really strong spark now. Pulled the new plug it didn't appear to be getting fuel. Pulled the carb. It is dry as a bone. I disconnected the carb from the fuel pump and turned the engine over. The fuel pump appears to be moving fuel well. A lot of fuel came out with just a couple of revs of the motor. So getting ready to read the manual on the carb.

jwstewar · Apr 25, 2012

**&(*^&*&^*&(&)&(*) grumble grumble, I came home tonight and instead of going in and changing close and looking at the diagram, I walked to the barn and started messing with the carb. I broke the high speed screw.

Fortunately I found 1 new one on ebay. $13 & free S&H. Also ened up ordering a new drain valve for the bowl and a new O-ring for it. Spent a total of about $20. After I order those I found a NOS carb for $60.

Should've just ordered that. If these parts don't work I will order it, the guy had 5 of them. I don't see all 5 of them selling before Monday or Tuesday.

jwstewar · May 21, 2012

OK, a little bit of an update on this. I was able to find the part I broke for the carb. Even managed to get a rebuild get for it. I cleaned the carb and can get air to go through everything and everything moves free. I replaced all of the old gaskets and such and replaced with the new ones. Still no start. Even spraying ether in in, still no start and doesn't even try. I bought a compression tester. It is building 120 PSI when I crank. So now I'm kind of stuck, not sure where to go.

In short:
I've got good spark now
rebuilt carb
120 PSI on the cylinder
Still no start even with Ether