# PLEASE HELP! Kohler K341/Gravely 5865 Burning Coils - New wiring



## t-craw

Hey fellas,
Finally finished with re-build of my Cousin's Gravely 5865 with the Kohler K341. In addition to re-building the engine, I've replaced the points, condenser, plug, ignition switch, solenoid and even had to rewire entire thing. I used 12 ga wire on new wiring harness and soldered almost every terminal/wire connection.

After about a 1/2 hour of running, it shut down like it ran out of gas. Found the coil was bad. Now this coil was NOT a Kohler coil but rather a 12V automotive coil purchased from NAPA with the internal resistor (it was the coil that was on it when I brought it home for re-building). Purchased another coil of the exact type from NAPA and that seemed to fix it. Ran it for nearly 4-1/2 more hours (was about to shut it down, change the oil and bring it back to my cousin's finished and broke in ready for him to use) when she shut down again. I just knew it was out of gas but it wasn't. It was that damned coil AGAIN! I had a used one lying around and I hooked it up and she starts again.

Now I fear I've got a problem and don't want to bring it back to my cousin until I determine what it is. I've read where you should only use the Kohler coil (Part #231281-S, 41-519-21-S) on these engines but I'm not about to go out and spend nearly 90 bones on a coil if I've got a problem that's going to burn it out too.

Here is the system that I think he has: It's a Battery Ignition type system, Electric Start with what I believe to be a 15 AMP Regulated Battery Charging System. Now I don't know that for sure but it's the closest thing that resembles the wiring diagram. Tractor DOES NOT have an optional Ammeter on it.

Upon failure of second coil, I started checking my wiring. Seems I made a stupid mistake in the ignition switch. Instead of having the Red/White wire from the B+ from regulator/rectifier going to the "R" terminal on ignition switch, it was actually on the "A" terminal. I switched it and put it on the "R" terminal but I don't believe this would cause failure of a coil. Correct me if I am wrong though. So now I start to run a few tests.

First test I did was output of the Alternator by unplugging it from regulator and checking A/C Voltage on both "AC" terminals. My throttle stop is at 3200 RPM so that is the RPM I checked it with and the reading was just 10.4 volts A/C. Manual says it should be 28 volts or more @ 3600 RPM. Would revving it up another 400 RPM's bring output up to 28 volts? I doubt it.

Second test was to check resistance across stator leads while engine stopped. Reading was 0.4 Ohms, NOT 0.1/0.2 like manual says it should be.

Third test was check resistance from each stator lead to ground. No continuity was present which means my stator leads were not shorted to ground.

I should note that my battery condition is not great. Measures 12.5 volts (not the usual 13-14.5 volts that's usually present in a new battery). I also painted the sheet metal which is where condenser attaches to but I checked for ground with meter and apparently the new bolt/washer used to attach it provides a good ground.

I'm kind of at my wits end here :argh:. I've got a problem with my coils burning up/failing after fairly short run cycles and now it appears that I've got an issue with the charging system. Not sure if coil issue is related to charging issue or not. I'm not an electrical tech and not too confident when it comes to troubleshooting things of this nature.

I do know I'm so ready to get this thing back to my cousin NOW but I just can't if there's this problem.

Any help, suggestions or instruction would be SO appreciated.


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## jhngardner367

Test the voltage regulator. 
Neg voltmeter lead touching a ground,and pos voltmeter lead to MIDDLE connector of regulator.
Should not go above 14.5 volts DC,at wide open throttle.
A faulty regulator will cook coils quickly.
Also,check to see if wires to coil are reversed.


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## t-craw

Have not checked voltage regulator, just stator output. I can tell you I did put a meter on battery while running and am only getting 12.5 volts. Will have to wait till tomorrow to check per your instruction. Can also say with confidence that coil is connected correctly (wire from ignition switch "I" terminal to + coil. Wire from points to - coil.


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## t-craw

jhngardner367 said:


> MIDDLE connector of regulator.


When you say "MIDDLE connector", do you mean the output (the red and white wire going to ignition switch), the B+ terminal?


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## jhngardner367

Yes. That is the regulated voltage. It is changed from 28volts AC,to 12-14 DC voltage to charge the battery.
Another thing to check,is that the coil body is tight in the clamp/mount. If it's loose ,it can damage the coil.
Was the coil getting hot(too hot to touch) ?
Another thought: was the battery low/dead when it died? It could be ,that it's running off the battery,until there's not enough voltage in it(minimum of 10.5 volts DC,to fire the plug).If so,may have an open spot in the switch/wire to the battery,from the regulator.
Disconnect the wire,at the battery or switch, that goes from the middle terminal of the regulator,and start the engine. Don't let it touch a ground. Touch the wire with the pos test lead,and the ground with the neg test lead.It should should read 12-14.5 volts DC. If not,there's an open spot in the circuit.
If there's voltage,you may have a bad switch.


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## bmaverick

This may be a little related. I have once upgraded my V8 to some higher sparking plugs and a heavy duty wire kit. Well, that was too much for the coil In a matter of 1-week the coil burned out, replaced it and almost a week later it did the same thing. 

So, I switched from the 9mm ignition wires back to the 7.5mm and never had a coil burn up again. 

So, that's was my experience. I agree, check the voltage regulator too along with the connection to ground. A simple ground strap helps big time, even if the engine didn't come with one.


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## t-craw

*Ok, I put charger on battery overnight (right now I've only got this 1 amp trickle charger as my big charger failed a few months ago), so earlier today battery was at 13.5 volts.

But before starting, I did some things to rule out some grounding issues. Although my multi-tester showed I had ground at both condenser and voltage regulator, I wanted to ensure it was not just an intermediate ground so I ran a grounding strap straight from battery to both voltage regulator and condenser. Now I know they are grounded.

I also had a used OEM Kohler Coil that's in good shape so I cleaned up brass terminal connections nice and shiny. Mounted it. Cleaned up high tension lead nice and shiny. Took the heavy 12 ga wire (what I used when creating new wiring harness) from NEW ignition switch to + coil terminal and replaced with smaller 16 ga wire. Made sure connections to NEW ignition switch was tight. Cleaned terminals from points wire to - coil nice and shiny.

As I said, upon starting, the battery was showing 13.5 volts. Started engine up and it ran so smooth from idle to WOT (which is currently set at 3200 RPM max). After running for 10-12 minutes I checked voltage (while running) across battery terminals at WOT. Reading was now 12.74 (dropped down from 13.5 in just this short amount of time). Throttled engine down to idle and no change was observed in voltage across battery terminals (still 12.74 volts).

However, after running for just 10-12 minutes, I started to notice an occasional brief misfire which was absent upon initial start-up. This is the same symptoms that were occurring when the last two coils failed..., occasional misfiring. Shut engine down, decided I would drain oil (remember this is a newly re-built engine with just slightly over 5 hours on it..., so time to change oil anyway). While oil was draining (approx. 5 minutes after shutdown) I took another reading across battery terminals and now it was 12.96 (slightly higher than before engine shut-down - 12.74 volts).

I want to run some additional tests on charging system (stator output, regulator output) but would like a full charge to be on battery before doing so. That means I've got to wait till tomorrow with this doggone 1 amp trickle charger on it.

However, my thoughts are this: After running a few tests yesterday on stator and regulator, I am thinking that my charging system is faulty (probably stator as yesterday's test showed very low A/C output and slightly higher resistance that specs should be). I feel that the current for the ignition is flowing straight from battery and when battery level starts dropping off it's causing a weaker spark at plug (which may explain occasional misfires) and also causing my coil to work harder to produce current needed..., leading to eventual failure of coil.

Tomorrow I will perform the tests again at the hot side of stator (at the first connector that leads to regulator) and a few on the regulator itself before I determine if one or both components are faulty.

Any thoughts on this?

Not ignoring previous suggestions for testing but as I said, I want to wait and perform these with full charge on battery.*


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## jhngardner367

Is it possible that a mouse chewed some wiring on the stator ? Test the 2 wires (usually white) that go to the regulator.
If you re-test the stator wires,make sure you use the AC setting. It should have 28 volts ac @ 3200 RPM ,or more,but not over 33vac,at each wire.
If there's a difference of more than 10vac between them,replace the stator.


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## t-craw

*OK, stator wires not a problem. Re-started engine today with 13.7 Volts on battery. Checked AC output at hot side of stator. Again - 10.1 Volts AC. Unplugged B+ from regulator/rectifier to ignition switch and read 0.15 Volts DC.

Pulled flywheel and looked at magnets. Guess what? Magnets in flywheel are not glued in correct order. Learned from my cousin that a few years back he said the magnets came loose and "ganged" up on inside of flywheel. He said he glued them back. However, I used a magnet I had lying around and checked each one inside flywheel and they are not in sequence (see pics - I've marked the poles on each one).

Now I know ONE reason I'm not getting correct AC reading from stator. Not sure if stator is bad or not but can't tell until I get these doggone magnets straight.

There lies my current problem. These magnets are glued in with epoxy. Not sure how to loosen epoxy. From my experience with fooling with epoxy, once it's cured, it's nearly impossible to dissolve/soften. So I'm not sure of correct route to take here. 

One more thing: One magnet is cracked but glued into place. If by chance I am successful in loosening and removing these, will it be an issue to glue this "cracked" magnet back in, ie: will if affect current production?

Any suggestions? *


jhngardner367 said:


> Is it possible that a mouse chewed some wiring on the stator ? Test the 2 wires (usually white) that go to the regulator.
> If you re-test the stator wires,make sure you use the AC setting. It should have 28 volts ac @ 3200 RPM ,or more,but not over 33vac,at each wire.
> If there's a difference of more than 10vac between them,replace the stator.


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## Beaner2u

Wow, 

That is quite a find, were the magnets marked like that or did you put the plus and minus signs on them? To double check the magnet polarity you can run a small compass along the edge from one end to another. 

I have not checked on as yet, but I understand that each or those magnets have three poles, +-+ or -+- and they must alternate positions.

The voltage regulators are a two part device, first a rectifier and then a regulator to control the charging voltage.

I don't know how much luck you would have try to remove a magnet.

Roger,


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## t-craw

*I marked the magnets just for reference (not meant to be correct in + or -, just for reference to see the differences). By feeling the repel or attract in the middle of the magnet it's easy to feel the difference so I did not use a compass.
You are correct with the 3 poles. You can feel them when you hover another magnet over them and they do need to be alternated next to each other.

I don't believe it's possible to remove these magnets once epoxied without destroying them. I feel my cousin (or I) will have to look for a replacement flywheel now.*


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## film495

I've heard some epoxy is easier to remove if you get it heated up. 

Question, how sure are you the magnets are wrong? Looking at the poles on your pic, do you just have to change the one magnet, so the poles alternate sequence? If that's possible, would seem to be the least intrusive.


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## jhngardner367

Try soaking the epoxy part with Acetone,or MethylEthylkeytone (MEK )either one can be purchased at Lowe's,or hardware store.
Just swab it on,liberally,and let it set for 2 min.,and repeat. Test each time to see if it has released.
Once they're out,clean magnets,and flywheel with rubbing alcohol,let dry and use epoxy to reinstall in correct order.

MAKE sure they are positioned for height/spacing/order !
The broken one should be tested for polarity,and,if it is ok,just fit it together,and install it.
Allow 48 hrs to cure.


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## t-craw

film495 said:


> I've heard some epoxy is easier to remove if you get it heated up.
> 
> Question, how sure are you the magnets are wrong? Looking at the poles on your pic, do you just have to change the one magnet, so the poles alternate sequence? If that's possible, would seem to be the least intrusive.


*The marks (+ and -) are merely marks that I put on each magnet to show the relative polarity. ie: Magnets marked + are of a particular polarity whereas ones marked - are of the opposite polarity. As Beaner2U mentioned, each magnet has a 3 pole polarity with each being either + - +. or - + -, and you can actually feel this by taking a square, thin magnet and using the thin edge, run it across top of magnet mounted inside flywheel. Starting from one end of the curved permanent magnet, it will actually either repel or attract the magnet in your hand and when you pass it over the middle portion of the permanent magnet, it will do the opposite of what it did at the end and of course, as you move it down to the other end, it will behave just like it did on the opposite end. Does this make sense?

That being said, looking at picture, I should have one magnet that is marked + with another magnet next to it marked -, so on and so on. On a 15 amp alternator (which is what this is) there are six magnets equally spaced (three are of one polarity and three of the opposite polarity) sequentially set next to each other in the order mentioned above. If I'm not mistaken, on a 10 amp alternator Flywheel, there are only 5 magnets, The polarity is staggered just as a 15 amp but there is a space where it appears a magnet is missing.

Point is the magnets shown in picture are not in the correct sequence and will not generate current like this. They need to be staggered in the fashion explained above to produce an A.C. current.

I've thought about using acetone but figured it would evaporate almost as quickly as applied. Thought about soaking entire flywheel in Acetone but have you priced acetone lately? Would be an expensive method for sure.

However, I'll give a shot at swabbing some on and see what happens.

Thanks for the 2 cents.*


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## t-craw

film495 said:


> I've heard some epoxy is easier to remove if you get it heated up.
> 
> Question, how sure are you the magnets are wrong? Looking at the poles on your pic, do you just have to change the one magnet, so the poles alternate sequence? If that's possible, would seem to be the least intrusive.


*In response to your question about changing just one magnet: Yes. Well, it's actually 2 that need to be swapped out. The ones at the 12 o-clock and 10 o-clock positions need to be swapped. Not all need to be removed. Guess that would save me from messing with the cracked magnet as I could leave it alone.*


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## jhngardner367

I think that should be the way to do it
I've had cracked magnets,before,and it hasn't seemed to affect the performance.
All the epoxy does is hold the magnets in place. Try to reset the 2 ,and give it a try. It can't hurt, right ?


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## Mickey

A couple comments. While relocating a couple of the magnets, you still have the problem of the windings reading .4 ohms in place of .01-.02 ohms. That is going to affect the output but can't say how much. Are you sure the reading is correct? If you touch the meter leads together can you get the reading down to zero? The lead wires and their connections offer some resistance. Some meters have a provision for resetting the reading to zero when the leads are touching.

Have you taken a voltage reading at the coil shortly after starting the engine. The reading should notably be less than 12 volts. (this reading should be take at the point side of the coil) If you can take a current reading at the coil, you should see something on the order of 3-4A. If the coil is getting hot, it is a sure sign the current flow is too high.

As for the battery readings you've seen. A fully charged 12V LA battery should read ~12.7 volts. The output from you little charger, 13.5 is a decent charge voltage. Shortly after removing the charger you will see a higher voltage on the batt terminals but let the battery sit for 4-5 hrs and the voltage will drop to the previously noted value. That quick V drop you noted is the surface charge on the battery and it is no surprise to see it drop quickly if you try and draw a small amount of current from the battery.


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## t-craw

*This morning I used a some fingernail polish remover and swabbed liberally on the two magnets. Did this about 3 times in 20 minutes. Tapped with rubber mallets. Nothing. Found some other solvent I had (Interlux 216 Special Thinner/Brushing Liquid), basically just Xylene and did the same. Tapped with rubber mallets. Nothing.

Then my cousin called and told me he remembered it was J.B. Weld that he used to glue in magnets. I'm thinking "oh my gosh..., they aren't coming out". I mean, I've used J.B. Weld to fix a cracked head on a cub tractor and it lasted for 15 years.

Well, he brought a heat gun over and with heat applied directly to magnets and a little finesse, out they came.:headclap: Not sure if it was due to combination of solvents and heat but at this point I don't really care. They're out and I've got some fresh J.B. Weld here so I'll just use the same method as he did before to attach magnets into correct location.

After it sets for a few days, I'll re-assemble and see what stator reads and hopefully will get good readings on it as well as regulator/rectifier.

Thanks for the suggestions. *


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## t-craw

Mickey said:


> A couple comments. While relocating a couple of the magnets, you still have the problem of the windings reading .4 ohms in place of .01-.02 ohms. That is going to affect the output but can't say how much. Are you sure the reading is correct? If you touch the meter leads together can you get the reading down to zero? The lead wires and their connections offer some resistance. Some meters have a provision for resetting the reading to zero when the leads are touching.
> 
> Have you taken a voltage reading at the coil shortly after starting the engine. The reading should notably be less than 12 volts. (this reading should be take at the point side of the coil) If you can take a current reading at the coil, you should see something on the order of 3-4A. If the coil is getting hot, it is a sure sign the current flow is too high.
> 
> As for the battery readings you've seen. A fully charged 12V LA battery should read ~12.7 volts. The output from you little charger, 13.5 is a decent charge voltage. Shortly after removing the charger you will see a higher voltage on the batt terminals but let the battery sit for 4-5 hrs and the voltage will drop to the previously noted value. That quick V drop you noted is the surface charge on the battery and it is no surprise to see it drop quickly if you try and draw a small amount of current from the battery.


*You are absolutely correct in regards to the resistance not being zero when touching leads together. Just checked and am getting .3 Ohms, which would mean I am getting a good reading when it checked at .4 Ohms (0.1 Ohms).

Have not taken reading at coil after starting engine. Give me a few days after these magnets set and re-assembly and I'll do just that.

Thanks for the info.Bye*


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## Beaner2u

Take a look at this for a replacement coil.

http://www.ebay.com/itm/Igintion-Co...S_Outdoor_Power_Equipment&hash=item1e87c83322


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## t-craw

Beaner2u said:


> Take a look at this for a replacement coil.
> 
> http://www.ebay.com/itm/Igintion-Co...S_Outdoor_Power_Equipment&hash=item1e87c83322


*Hey Roger,

What I have on this engine NOW (after burning up 2 coils with the internal resistor - not OEM Kohler p/n but NAPA brand) is actually the correct OEM Kohler Coil made by Diamond. It's is the correct part number for this application.

However, I've researched quite a bit on this issue about coil failure, etc. From what I've read, an epoxy filled coil is much more resistant to vibrations than an oil filled coil (which is what the Kohler OEM coil is). Although it's supposed to be heavy duty, it's still oil filled nonetheless.

If I do purchase another coil for this engine, I think it will be an epoxy filled type. Even though I may require an inline resistor between ignition switch and coil as well as 2 condensers for some of these high output, epoxy filled coils, it's not a problem for me to do that if it will prevent coil failure, if in fact, my problem is/was from excessive vibration. 

At this point I'm inclined to think my problem of coil failure was due to this faulty charging issue which made more current flow through coil due to low voltage, thereby burning up the coil.

Some example of epoxy filled coils I've been watching are:
http://www.ebay.com/itm/310866867508?_trksid=p2055120.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

http://www.ebay.com/itm/151227955422?_trksid=p2055120.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

http://www.ebay.com/itm/111277397255?_trksid=p2055120.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Thanks for your information.
*


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