GT-14 BlackBeard's Pacemaker!

[PeacemakerJack 10,738]

I'm opening this thread here in the appropriate area but it is tied to the Blackbeard thread in "restorations".  I was driving the 14 tonight and it stopped running just like I had shut off the key.  As I understand the firing system on this beast (please correct me if I'm wrong) the starter turns the engine over once you turn the key and once it is running, it runs on its own.  Then to turn it off, you turn the key and the Mag kill wire grounds it out.  I believe it is a very similar design to the Magnum series motors released in the 1980's.  As I see it, the rest of the electrical system is separate from the above mentioned.  My key turns over the motor fine, the headlights and taillights work fine, the ammeter works.  So, it seems that the problem is isolated to either the Mag kill switch, trigger, coil or wire between the ignition switch and spark plug...again correct me here if I'm looking at this wrongly.

 

So---tonight I took the plug out, put the coil wire on it, and grounded it to the frame, NO SPARK.  What is the testing sequence from here? Is there anything that I could've done that would've damaged the coil or the trigger?  Is there a way for me to test the coil to see if it is still good?  I know these are very expensive as I've done some poking around on here.  What about the trigger, would that have failed?  Is there a way to test?  Zach really wants to use Blackbeard this summer and I'm doing my best to make that a reality for him...

[PeacemakerJack 10,738]

A little more info:

1.) disconnected the mag kill bullet connector at the coil to make sure that it wasn't the key switch or the wire grounding out up to the coil keeping it from starting. Still no fire!

2.) hooked my multimeter to the female spade connector after disconnecting it from the coil. Set it to Volts and received read outs 14-30 volts in about 10 revolutions of the motor.  Can I presume that the trigger is doing its job?  

 

I seem to to think that the coil is my problem. I have a functioning coil on my other GT-14.  I'm afraid to put it on here if something killed this one. Thoughts???

[953 nut 55,033]

Sound right to me, if you use the known good coil on "Blackbeard" with no wires at all connected to it and have spark that would confirm it. @Aldon did a conversion to a battery ignition using points, search his posting on this or perhaps he will chime in here.

[tbarnhart 240]

Those ignition systems were totally different from anything Kohler used anywhere else, and were similar to the Tecumseh SSI ignitions that they started about the same time. Tecumseh continued to use a solid state system, but Kohler went back to a battery ignition with mechanical breaker points. In many ways, the solid state transistorized ignitions were better, but the early electronic components weren't as good as modern stuff, as well as the fact that it's all about 45 years old. It really functions as a capacitance discharge system (CDI) which is commonly used today on atvs and motorcycles. You have three basic parts to the system and any of them could fail, although it is often the small trigger module mounted above the flywheel. Under the flywheel, the stator coil is actually a double wound coil. One coil sends two wires with AC current into the regulator/rectifier to charge the battery. The other coil is internally grounded and sends one wire with AC current to the trigger module above the flywheel. This is also where the kill wire to the M terminal is connected. If this circuit is grounded, the trigger loses AC power and the spark stops. The second part is where the magic happens. In that little box above the flywheel is the electronic circuitry to store current in a capacitor and trigger a pulse to the coil when the flywheel trigger comes past the module. These modules are often the failure point in any CDI system as they have to deal with rapid current charging and discharging, as well as the vibration, heat, and other environmental stress. The timed pulse of current is then sent to the exterior coil, where the voltage is elevated enough to fire the spark plug. This "coil" is distinctly different from a battery ignition coil. In battery ignition, the coil stores energy in a magnetic field, and releases it as a high-voltage spark when the field is collapsed. In a CDI system, energy is stored in a capacitor and is simply released to a pulse transformer "coil" where the voltage is elevated. As far as testing the Kohler system, I think the appropriate Kohler manual would have a few pointers, but there is really not much that can be be tested. The AC output from the stator can be tested, but you already did that and your reading sounds about right. The pulse transformers rarely go bad, so I would guess its the trigger module. One thing that will kill those systems is 12v DC on the kill wire. It should never have battery voltage on that wire. It should be open circuit for "run" and grounded for "stop". I've got a Tecumseh OH160 in my horse that has died a couple times. So far, I've been able to dig the potting out of the module and replace a few defective diodes. Never dug into the Kohler system that much. I was looking at using atv/cycle parts  to come up with a replacement system should my module fail again. Never followed through with it as mine is still running.

[pfrederi 17,643]

You can test the coil easily with a multimeter.  Trigger testing requires pulling the flywheel.

[Aldon 4,826]

Here is the thread I have been working on doing the conversion from CDI to Points.

 

I had to stop and do front end brake job on my Horse Hauler but hope I can get the conversion project finished in next several days. Hopefully by the end of the weekend and Ill try and update the thread.

 

BTW @PeacemakerJack , the symptoms you described for your failure were identical to what happened with my Lazarus GT14. I did not troubleshoot to which particular part of the CDI had failed but as I had completely rewired the tractor and had all new components other than the CDI I deemed it more efficient o just swap the older electronics out. I likely would have done it sooner but had some anxiety over removing the plug that the Points Push Rod slides through. As you can see in the attached thread, It is not a difficult operation once you have done it. Of course I say that not having actually finished and fired the engine up to test

 

 

[PeacemakerJack 10,738]

Thank you very much guys for your informative, technical yet practical responses!  You guys are what really make this a great site! I'm busy at work now but if I can carve out some time later in the day, I'll run some more tests and report back here with the results.  I'd like to retain the CDI system if I can but not if it will cost me hundreds of dollars to do so.  

[PeacemakerJack 10,738]

Some good news here!  I put my spare CDI unit on after testing all wires associated with it and the tractor started right up.  Points to ponder (or weigh in on!):

1.) discovered that the spark plug I put in was never tightened . Which got me to reading the warning on the engine tin which says never to pull the plug wire while running or you may permanently damage the coil.  Could a loose enough plug caused damage?  

2.) ran a resistance test on the suspect coil.  It was 11.7 ohms.  Not sure if that is elevated enough to be a problem?  The coil I replaced it with was 11.4ohms.  

3.) I checked the "mag kill" wire with the key in the start/run/accessory position and there was thankfully no juice there

4.) how important is good ground to the function of these CDI units.  When I took mine off, I noticed a lot of rust between it and the flywheel shroud.  I made sure to sand to bare metal on both the "ears" of the replacement coil and the attachment area of the shroud.

5.) I mentioned about the readings that I got from the trigger module last night.  

 

I've got to assume that the coil was the problem since it is running now but that resistance reading isn't as far off as I thought it would be.  

[tbarnhart 240]

I'm guessing, from reading the manual that pfrederi posted above that your readings are probably 11.4-11.7 Kohms. I would say that that is good. The ground of the coil as well as the ground of the trigger module is important, so that may have been the problem. It's also possible that even though the trigger module is working now, it may be intermittent or sensitive to heat. It's not uncommon for electronics to work when cold, but fail when hot. You could reinstall the original coil and see if it changes, and run it for a few minutes to let the ignition system get up to temp and see if anything happens. If you have to replace the coil, they're probably easier to find than the trigger module. Keep us updated.

[Aldon 4,826]

7 minutes ago, tbarnhart said:

I'm guessing, from reading the manual that pfrederi posted above that your readings are probably 11.4-11.7 Kohms. I would say that that is good. The ground of the coil as well as the ground of the trigger module is important, so that may have been the problem. It's also possible that even though the trigger module is working now, it may be intermittent or sensitive to heat. It's not uncommon for electronics to work when cold, but fail when hot. You could reinstall the original coil and see if it changes, and run it for a few minutes to let the ignition system get up to temp and see if anything happens. If you have to replace the coil, they're probably easier to find than the trigger module. Keep us updated.

Great Post. 

 

My thoughts as well.

[PeacemakerJack 10,738]

I will definitely keep everyone in the loop as far as the electrics go in this thread.  I have my fingers crossed that this will work for awhile.  As was commented on earlier, I must remind myself that this is a 46 year old tractor that is mostly original!!! Needless to say, it has certainly outlived any of the original designers expectations.  It is awesome to reflect on how well these horses were built.  Years of use and abuse yet somehow they keep on going.   power at its finest!

[PeacemakerJack 10,738]

On July 7, 2016 at 9:17 PM, tbarnhart said:

It's also possible that even though the trigger module is working now, it may be intermittent or sensitive to heat. It's not uncommon for electronics to work when cold, but fail when hot. You could reinstall the original coil and see if it changes, and run it for a few minutes to let the ignition system get up to temp and see if anything happens. If you have to replace the coil, they're probably easier to find than the trigger module. Keep us updated.

I hate it when you guys are right if it costs me money! . Last night I decided to take Blackbeard for a ride around the property.  He started up almost instantly with a little choke and about 30% throttle. He was running pretty good, then I backed him out of the shed and started to drive when it was once again like someone shut off the key!So, I think we have a failure of the trigger module or the wiring leading to it.  Now what? Do I spend the big bucks on a replacement, or do I change the one from my other tractor, or do I switch to a conventional points system? Decisions! What do you guys think?

[tbarnhart 240]

You had mentioned that you would like to keep the tractor original as much as possible. In that regard, you only have two options. Take the trigger off the other tractor and then have to retrofit something to it later, or locate another trigger module. If you have a friend/local electronics guru with a lot of curiosity, you may be able to get it repaired. You could always switch to battery/points like Aldon did and go back to the standard Kohler stuff, but I personally like the breakerless system better. It's maintenance free, self powered, and won't drain the battery if you leave the key on. No adjusting points, checking wiring connections to the coil or dealing with weak spark because of a bad condenser. The downside is the simple fact that these electronics are 40-45 years old and are prone to failure at any moment. Even after spending big bucks to get a trigger, it's still going to be an old one. The Tecumseh system like I have is the same way. Used modules are still $200 and you don't know when they are about to die as well. I guess that's the reason I fixed mine, and I was thinking of retrofitting some atv ignition parts in the case I wasn't able to keep it running. It seems fine now, and I love the way it works. Time will tell.

[PeacemakerJack 10,738]

I just left on vacation for the Black Hills but it will give me something to think about while our here.  Do you know if any of these parts(module, coil, stator, etc) are available NEW through Kohler or Toro?  Or are they only available as used parts or the occasional NOS?

[tbarnhart 240]

As far as I know, only used or NOS. I don't think Kohler has made them for a long time. They only used the system for a few years, and that was over 40 years ago. It was never sold in huge numbers like the battery/points system so aftermarket companies never saw the demand to get in the market.

[PeacemakerJack 10,738]

If that don't beat all!!! I come home from a week trip to the Black Hills and decide on a whim to try to start Blackbeard.  I pull the choke, set the throttle, and turn the key it rolls over about twice and starts right up.  So, I definitely have a glitch in the electrical and it seems to be the trigger module.  What is the most efficient way to change that out?  I'm sure I can figure it out but I'd much rather glean the tips from those of you who have done it multiple times...thanks

[pfrederi 17,643]

You have to pull the flywheel then it is easy.  Check out the test you should do once it is off...(above)

[PeacemakerJack 10,738]

30 minutes ago, pfrederi said:

You have to pull the flywheel then it is easy.  Check out the test you should do once it is off...(above)

I'll definitely do the test.  Any tricks to yanking the flywheel?

[Aldon 4,826]

If I recall, you may not be required to pull flywheel. The trigger mounts on the upper left corner under the engine shroud.

 

Depending on how the two wires are attached to the trigger will mandate whether you absolutely must pull flywheel.

 

To ascertain the condition of the wire from the armature/windings to the trigger, you would absolutely need to pull flywheel.

 

 

[Aldon 4,826]

As far as pulling the fly wheel off. Plan on at least a couple days.

 

Start by spraying E-Force, Kroil or PB Blaster and let it work a couple days.

 

The front of the flywheel has a couple holes to thread bolts to use a flywheel puller with.

 

If you have taps' I would clean the threads first.

 

Be careful that you do not damage the internal thread on the shaft that the flywheel rides on as that fine thread is how you will re-attach the PTO and you don't want to damage threads. Ask me how I know this:-)

 

I now have a fine thread tap that I did not have previously.

 

For puller, I have only had to use lots of heat on the last one. Usually impact wrench after a few days of soak and it breaks free. I used the HF puller for the flywheel.

 

PS, Not the claw type as that will break the flywheel. I used the puller that allows you to pull on the bolts inserted into front of flywheel.

 

I 

Edited July 20, 2016 by Aldon