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Sears GT/18 - Tecumseh solid state: help needed!

sears gt16 gt18 oh16 oh18 loader tecumseh solid state no spark

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#1 money89tractors OFFLINE  

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Posted February 22, 2016 - 10:55 PM

I have an unknown year Sears GT18. I knew the year once but lost that info. It has a factory front end loader and rear 3 point grader/ripper box. I bought this machine over a year ago while i was searching for a small bobcat. I had always wanted a garden tractor with a loader and couldnt pass up this thing. Its been a great unit until now. . . 

 

When i bought the tractor i was not happy that it had a tecumseh engine (i have never had anything good to say about them, ever), but at least this has the cast iron engine that seems to be a bit better,

 

A few days ago i was using the tractor to do yard work and it was running/working as normal. The day was the first time it had been started for a couple months. I shut that tractor off when i was done for the day and left it. When i attempted to start it the next day it absolutely would not start. So i went through the normal checklist. Turns out it had no spark. Ive been attempting to figure out why it suddenly stopped firing for 2 days now. Here is what ive done so far:

 

- changed the plug (gapped appropriatly)

- removed the kill wire from the coil hoping it was a short in the kill system

- changed the solid state coil with another one from a parts machine

- Ensured my gap between the trigger pins and ignition unit was correct

- ensured the trigger magnet on the ignition unit was clean, as well as the trigger pins

 

Still absolutely no spark. 

 

I do have a downloaded pdf of this engine, but the information is a bit limited. I am not completely sure how this solid state system even works, which may be why im so confused on what the issue is.

 

Here is a few pictures of the GT18:

IMG_20140805_231341_zpssf2bqzsp.jpg

IMG_20160220_164821151_zpszix9av1n.jpg

IMG_20160220_164836919_zpsamxqe4rb.jpg

 

Here is the numbers stamped on the cover of its engine:

IMG_20160222_180047675_HDR_zpsqh3g5tve.j

143 700012 SER 0077E

 

Here is a picture of the ignition unit from it:

IMG_20160222_180343373_zps14yn8znf.jpg

 

Here is a picture of the ignition unit i installed from the parts machine, along with the numbers from that engine:

IMG_20160222_180308652_zpscl2jtqpi.jpg

IMG_20160222_180605205_zpsyvrcs7lo.jpg

143 670032 SER 7298E

 

And here is a picture of the 2 side by side (original ignition unit on the left)

IMG_20160222_180433585_zpsupgknxes.jpg

 

 

I have noticed that the kill wire ran down behind the flywheel, so i pulled the flywheel and found this:

IMG_20160222_175848834_zpsyzrmyb1s.jpg

 

One magnet for the charging unit is no longer attached to the flywheel, so ill need to find a way to reattach it to the flywheel (any suggestions on a glue, locktite, or epoxy?)

 

Any and all help here is greatly appreciated, Thank you.


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#2 Texas Deere and Horse OFFLINE  

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Posted February 22, 2016 - 11:01 PM

Sorry to hear of your issues. I can't help with the ignition, but you can use JB Weld to glue the magnet back onto the flywheel. Clean both areas very well before gluing them back together and use a C-clamp to hold it on while to JB sets up overnight.

 

Good Luck.


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#3 money89tractors OFFLINE  

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Posted February 22, 2016 - 11:07 PM

Sorry to hear of your issues. I can't help with the ignition, but you can use JB Weld to glue the magnet back onto the flywheel. Clean both areas very well before gluing them back together and use a C-clamp to hold it on while to JB sets up overnight.

 

Good Luck.

Thanks for that bit of info. Every little bit helps. I was unsure if jb weld would have enough holding power to keep the magnet in place. 



#4 Tecumseh power ONLINE  

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Posted February 22, 2016 - 11:13 PM

You can epoxy the magnet back on with 2 part epoxy. These tecumsehs that are cast iron are great engines. The first thing you need to do is check the wire that goes from the stator to the solid state. This isn't the kill wire it is the charge wire for the solid state. Look at it very close for cracks in the jacket . They often crack and arc off the cylinder. If it is cracked cut the terminal off the end and put heat shrink on the wire to cover the crack. Then put a new end on. Also check it for weak spots sometimes they break in the jacket. In that case you can fix it. Next meter. It. It should be a 20 amp system put the black meter lead on the stator base and the red on the wire that goes to the solid state . It should read around 137 ohms. If it reads good wiggle the wire and make sure it doesn't change if it does there is a break in the wire you didn't see and you'll have to fix it. If that all checks good. Get back on here and I'll tell you what to do after that . That clear 2 part epoxy works really well to put those magnets back on . They are easy to fix and re attach don't get stressed out about it. The spark problem can be fixed too. And that oh180 is a very good engine. And very heavy you will really like it. They last forever. I do alot of them so we will help you the best we can
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#5 Tecumseh power ONLINE  

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Posted February 22, 2016 - 11:15 PM

And your gt18 is a 1979 you can tell by the stickers on the hood the 78 had the gt18 on the side of the dash. Both those ignition module will work. They just made two differnt styles. Also check the air gap on the module to the long trigger pin on the flywheel. It should be 10 thousands. Adjust it to that with a feeler gage if it isnt

Edited by Tecumseh power, February 22, 2016 - 11:17 PM.

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#6 money89tractors OFFLINE  

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Posted February 22, 2016 - 11:26 PM

You can epoxy the magnet back on with 2 part epoxy. These tecumsehs that are cast iron are great engines. The first thing you need to do is check the wire that goes from the stator to the solid state. This isn't the kill wire it is the charge wire for the solid state. Look at it very close for cracks in the jacket . They often crack and arc off the cylinder. If it is cracked cut the terminal off the end and put heat shrink on the wire to cover the crack. Then put a new end on. Also check it for weak spots sometimes they break in the jacket. In that case you can fix it. Next meter. It. It should be a 20 amp system put the black meter lead on the stator base and the red on the wire that goes to the solid state . It should read around 137 ohms. If it reads good wiggle the wire and make sure it doesn't change if it does there is a break in the wire you didn't see and you'll have to fix it. If that all checks good. Get back on here and I'll tell you what to do after that . That clear 2 part epoxy works really well to put those magnets back on . They are easy to fix and re attach don't get stressed out about it. The spark problem can be fixed too. And that oh180 is a very good engine. And very heavy you will really like it. They last forever. I do alot of them so we will help you the best we can

 

From the reading i had done, i was hoping you would be the guy to see this post quickly. I was thinking the wire from the stator to the ignition unit was a charge wire, but some research told me it was only a ground to kill it (similar to nearly all briggs engines). . . obviously that information was wrong. . . . glad i didnt just shove power to it.

 

As stated, i dont mind these older tecumseh engines much, they seem to do well. Its the newer (aluminum) engines that i never had luck with.

 

Knowing that the wire to the ignition unit is now a charge wire, this system makes compete sense to me now, I was so lost on where it created power for the coil.

 

Also, the charge wire to the ignition unit: with the key off i get continuity to ground. With the key on i have an open circuit. I assume this is correct.

 

If i had to guess, im going to say that the magnet is my issue really? since with it laying directly on the stator would not allow the machine to charge the coil?

 

This GT18 has never charged the battery, I never looked into it. However, during my search for this spark issue, i found the charging system unplugged.


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#7 money89tractors OFFLINE  

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Posted February 22, 2016 - 11:27 PM

And your gt18 is a 1979 you can tell by the stickers on the hood the 78 had the gt18 on the side of the dash. Both those ignition module will work. They just made two differnt styles. Also check the air gap on the module to the long trigger pin on the flywheel. It should be 10 thousands. Adjust it to that with a feeler gage if it isnt

I had to adjusted to 8 thousands. . . .the pdf i have said 6-10, figured mid range was good.



#8 Tecumseh power ONLINE  

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Posted February 22, 2016 - 11:31 PM

I had to adjusted to 8 thousands. . . .the pdf i have said 6-10, figured mid range was good.

8 is fine.
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#9 Tecumseh power ONLINE  

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Posted February 22, 2016 - 11:37 PM

From the reading i had done, i was hoping you would be the guy to see this post quickly. I was thinking the wire from the stator to the ignition unit was a charge wire, but some research told me it was only a ground to kill it (similar to nearly all briggs engines). . . obviously that information was wrong. . . . glad i didnt just shove power to it.

As stated, i dont mind these older tecumseh engines much, they seem to do well. Its the newer (aluminum) engines that i never had luck with.

Knowing that the wire to the ignition unit is now a charge wire, this system makes compete sense to me now, I was so lost on where it created power for the coil.

Also, the charge wire to the ignition unit: with the key off i get continuity to ground. With the key on i have an open circuit. I assume this is correct.

If i had to guess, im going to say that the magnet is my issue really? since with it laying directly on the stator would not allow the machine to charge the coil?

This GT18 has never charged the battery, I never looked into it. However, during my search for this spark issue, i found the charging system unplugged.

the plug that goes to the regulator from the stator has three wires. The middle wire is the magneto wire the two side ones are the charge wires. It goes into the regulator . The two out of the regulator to the tractor are one green and one red. The green one is now the magneto wire. It gets grounded with the key in the off position . That is what kills it the red one is the charge one. Could very well be the magnet but while you have the flywheel off check that stator out really good. And fix that wire if you need to

Edited by Tecumseh power, February 22, 2016 - 11:38 PM.

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#10 Tecumseh power ONLINE  

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Posted February 22, 2016 - 11:41 PM

How were you shutting if off with that plug unplugged? I hope you weren't pulling the wire off the spark plug that will ruin the solid state. Unless they had that middle wire ran to the key, you can do that
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#11 money89tractors OFFLINE  

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Posted February 22, 2016 - 11:47 PM

How were you shutting if off with that plug unplugged? I hope you weren't pulling the wire off the spark plug that will ruin the solid state. Unless they had that middle wire ran to the key, you can do that

it has always been killed with the key. The only time i have unplugged the charge wire to the solid state was after it developed this no start situation.


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#12 Tecumseh power ONLINE  

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Posted February 22, 2016 - 11:49 PM

Here is a stator from a panzer 1110 that I fixed for a guy that had no spark, this one was supposed to be guaranteed to work from a guy on ebay who sells many of these parts. Well I got it and I put it on and it had no spark. This is that charge wire and where it was broke. So you can see what to look for. It is an hh100. But it'd the same system as the oh180

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#13 money89tractors OFFLINE  

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Posted February 22, 2016 - 11:56 PM

Here is a stator from a panzer 1110 that I fixed for a guy that had no spark, this one was supposed to be guaranteed to work from a guy on ebay who sells many of these parts. Well I got it and I put it on and it had no spark. This is that charge wire and where it was broke. So you can see what to look for. It is an hh100. But it'd the same system as the oh180

Absolutely great information. I will test everything tomorrow and report back, hopefully with a running machine.

 

As a side note question, my parts engine: I pulled the flywheel on it as well. Its in worst shape than the other (every magnet came off). . . I know now, that epoxy is good enough to put them back on, but; is there a was to make these engines run without that stator under the flywheel? With just a battery? or will a direct power from a battery to the solid state fry it?



#14 Tecumseh power ONLINE  

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Posted February 23, 2016 - 12:00 AM

Tahoe does alot of these also, if he reads this he will chime in. He will probably tell you anything I may have left out. He is pretty good with them also. Probably better than me he fixes the solid states I don't do that if I have a bad one I make a new pickup for a 12v coil.
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#15 money89tractors OFFLINE  

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Posted February 23, 2016 - 12:04 AM

Tahoe does alot of these also, if he reads this he will chime in. He will probably tell you anything I may have left out. He is pretty good with them also. Probably better than me he fixes the solid states I don't do that if I have a bad one I make a new pickup for a 12v coil.

 

That was my next option if i couldnt get this solid state figured out. Was to make a pickup that would use a 12v coil and an ignition module of some sort.







Also tagged with one or more of these keywords: sears, gt16, gt18, oh16, oh18, loader, tecumseh, solid state, no spark

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