cranking issues

Y

yellowhousejake

New member
Good afternoon,

I have a Cub Cadet 100 that we used for many years plowing snow and cutting grass. It went to the barn four years ago when a neighbor started plowing for us and we bought a Ferris ZTR for mowing. This year I dragged the cub out and had the engine rebuilt, planning to plow again this winter. The rebuilt engine runs great and it got it's first hour run and oil change with no load. I've been fighting with the tractor ever since.

In the last two weeks I have replaced the coil, wiring harness, condenser, plug wire, VR, and rebuilt the SG (new bearings and brushes) all to fix "the next thing that went wrong". At first, the SG turned very slow when I started the engine and I tried a second one I had, it too turned slow and clunked. That was went I pulled both SGs apart and found one with a burned amature, the other with bad bearings. I put the new brushes and bearings in the good SG and it spun up just fine. Installed the belt and the engine started right up. I ran around the yard to warm up the engine and set the governor, tested the mower deck, and checked the SG output (11.5 V at full throttle). I shut the engine down to read up on adjusting the VR and when I went back to start the tractor the SG would not turn the engine over.

I removed the belt, disconnected the field leads, and tested the SG and it now turns at 30 RPM with a fresh battery and no load. The commutator looks OK, mica is lower than the bars, brushes new, field coils not shorted. It's "one more thing wrong".

I love this little tractor, plows like a monster, I want to get it running again. I don't know for certain if my SG is bad and not sure where to go next other than buy a new SG.

Any thoughts? Advice? Mockery?

Thanks,

DAve
 
What is the serial number on your 100?
The early serial numbered IH Cub Cadet 100s had a cam that did not have a compression release built in it. My 100 had the same problem. The serial number on my 100 is 84XXX. Your 100 should have a small pulley on it. My 100 didn't have a small pulley when purchase it (It still running a big pulley). I would ask the party who rebuilt the engine if your Cub Cadet's engine has a 2 piece cam.

Any 1 piece camshaft from a K241(10 HP) to a K341 (16 HP) are the same lift-duration and will fit.
I wanted more power so I change the cam to a newer 1 piece cam. The cam I installed has more lift-duration.

If your 100 has a 1 piece cam the compress release may not be working right.

Did the party who rebuilt the engine measure the cylinder bore and crank shaft/connecting rod per the Kohler manual?
Did the rebuilder tell what size piston and connecting rod he used?
Another issue I see is the rebuilder didn't set crankshaft end play rod per the Kohler manual.
I have work on too many so called rebuilt engines that the rebuilder just put rings in and called it a rebuilt engine.
 
Couple of possible issues.

1. Battery condition. The small batteries for garden tractors don't last long, perhaps one year, two years if your lucky.
2. Check the battery terminals, cable terminals and ground to frame. Slow cranking over the engine could be either issue #1 or #2 or both.
3. Current voltage regulators are "cheap". Pays to spend the extra bucks for a good quality one.
 
Thanks for the quick responses!

I've rebuilt many an engine over the years, but this time I just didn't want to bother, so I sent it out. The engine was rebuilt by Kustom Lawn and Garden out of Minerva OH. I checked over the engine thoroughly when I got it back and it looked to be a quality job. They did do a full overhaul including dip and blast of the block. The rod bolts were new and even marked after being torqued.

I don't have the tractor SN in front of me but the SG is slow to turn unloaded (no belt) and the field wires disconnected. When it cranked the first time this morning, it turned the engine over "smartly" and started right up. It was the second time I tried to start it that the SG could not pull the engine over. It was then I tested the SG unloaded. I don't think it is a tight engine or compression loading causing the issue. My tractor does have the smaller SG pulley.

Here is the full rundown of what I have done.

- installed rebuilt engine. New gaskets, new belts, new plug, new plug wire, new muffler and exhaust nipple, carb overhauled, new fuel line, sediment bowl and valve cleaned, and a paper fuel filter added between valve and carb.
- Started and ran for 45 minutes at 3000 rpm (checked with tach). Engine running a bit rough for my liking.
- Changed oil, new coil and condenser (they were very, very old)
- Started engine and set idle and main jet screws. Engine running smoothly now.
- Drove to the end of the driveway and back. Turned off the ignition and the wire harness melted the field wire from the SG as the SG tried to crank.
- Rewired the tractor. Double checked the wire harness and then checked it again.
- Checked the VR and found an internal connection from the field term burned.
- Replaced the VR.
- Tried to start the engine and the SG would not turn the engine over.
- Checked the wire harness again.
- Pulled the SG and replaced with a spare. It would turn, but slowly and 'clunked' each revolution.
- Checked the original SG and found the armature had shorted and I could see the lacquer burned off several windings. Multimeter confirmed a short.
- Checked the second SG (clunking one) and found brushes nearly worn out and bearings rough. Field coils good and armature not shorted.
- Installed new bearings and brushes in the second SG and tested with a battery. Spun up nicely. Installed on tractor.
- Started tractor with rebuilt SG and it fired right up.
- Drove through the yard, tested the mower deck, set governor for running under load. No surge, no wandering rpm, 3600 rpm on the tach.
- Checked the SG output with a volt meter and found 11.7 volts at full throttle checking at the A post.
- Shutdown engine (no wire harness meltdown this time)
- Came back one hour later and tried to start engine, SG does not turn.
- Removed belt and field wires from SG, jumped off my running truck, hit the start button, SG turns at maybe 10 rpm.
- Removed the SG cap on the brush side and everything looks fine. Both brushes engaged, wires intact, commutator unburned. SG will turn freely by hand.
- Sat down, stumped.

My SGs are original and I was the first to open them up. I am unsure what I need to test. VRs are hard to come by locally and range in price from $24 (Amazon) to $100 (Napa). The $24 dollar one I just bought is identical down to the color, style, and location of the printing as the $100 one I bought ten years ago.

I'm perplexed where to go from here.

DAve
 
I am an idiot.

Standing in the shower last night after my last post, I was running through the wiring in my head as I was certain I did something wrong. Tracing each wire from terminal to terminal in my head, I realized my mistake.

I SHOULD have checked the wire harness a fourth time. I, for no obvious reason, put the GEN wire on the field post of the SG. Once I did so, it looked normal to me every time I checked it. The SG ends of the harness were the only ones I did not label as I started there when I rewired. I checked it as soon as I got out of the shower and yep, the GEN lead from the VR was wired to the field SG post. I tore down the SG and the armature is now shorted.

Funny how once you see something wrong, as correct, your brain continues to tell you it is right.

I will be back with the results after I replace the SG.

DAve
 
Well,

New SG installed and leads connected properly. Started the engine up and let it run at half throttle for about five minutes. Shut it down and it started right back up, no slow down on the SG. I mowed for 20 minutes, checked the SG output (13.7 volts), and turned the engine off. My wife and I went to dinner with the kids and when we came home three hours later, the SG turned the engine right over and it started on the second revolution. It's fixed. The new engine is strong and smooth running.

Thank you everyone for listening to my rambling. Sometimes just saying it all out loud, or typing it, is all you need to get your thoughts in order.

DAve
 
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