Faulty Stator Causing Electrical Short Tripping Breaker??

pgee

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  • / Faulty Stator Causing Electrical Short Tripping Breaker??
2002 48" Walker MTGHS with CH20S Kohler 64554 Engine. Approx. 600 hrs. Not an EFI. Gasoline. One owner. Well maintained. Cannot identify electrical short.
Issue: While in RUN, engine running or not running, Red and Purple wires at ignition switch become extremely hot, ultimately tripping 30A auto reset breaker.
What I know:
1. Red is battery ("B"), Purple is accessory ("A"), Purple feeds control panel accessories (oil pressure, head temp, voltage meter, hour gauge) AND is the B+ feed to the regulator/rectifier ("VR") see MT Electrical Schematic and Kohler Wiring Diagram, attached hereto
2. This is an electrical issue and not a fuel delivery issue.
3. Battery good.
3. Starter/solenoid good.
4. No noticeable compromise to wiring.
5. anti backfire solenoid good.
6. ignition switch good.
7. safety interlocks good.
8. Issue goes away when I disconnect the VR.
9. VR adequately grounded.
10. With VR disconnected, and engine running, the two white stator wires (2 wires of 3-prong plug connecting to VR) put out AC 42A. Purple B+ wire (3d wire of 3-prong plug connecting to VR) measures 12+v, which all makes sense.
11. But, with VR disconnected, and engine running, the two stator wires show a short to ground.

Could the short to ground in the stator be the cause of the Red and Purple wire becoming extremely hot at the ignition switch, ultimately tripping breaker? Or is there a diode(s) in the stator wiring that is causing this phenomenon?

The wiring diagrams do not reflect diodes in the stator wiring, but there must be diodes involved either in the wiring or in the VR to convert AC to DC. I haven't wanted to pull the engine to access wiring and stator. Hoping it is something else I can fix without replacing stator, or magnets because of difficulty pulling engine from Walker frame.

Here is what is gong to engine from engine harness plug:
Red wire connected to Purple wire, which is the B+ feed from VR back through ignition switch to charge battery, and anti backfire??
Red wire connected to Blue wire (blue goes to starter solenoid, Red to anti backfire or other??) I know anti backfire engages in Run and Start
white kill wire to magneto
one green wire, presumably going to oil pressure switch
Two black wires connected at same terminal (presume that one goes to the head temp switch; don't know about 2d black wire??)

Hoping this is not too much information that it is confusing. I need help understanding why the Red and Purple wires at B and Acc at the ignition switch are getting hot and tripping breaker when in Run position. All signs point to bad stator but hoping it is something else.

Really do appreciate any and help you might give me.

Thanks

PS. Tried to upload the Kohler CH20 Service manual that contains the wiring diagram but file too large
 

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bertsmobile1

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  • / Faulty Stator Causing Electrical Short Tripping Breaker??
You need to adjust your thoughts a little regarding electricity
The mower has 2 power sources, the battery ( red wire ) & the alternator ( purple wire)
The red wire supplies power when the engine is not running.
The purple wire supplies power when the engine is running.
In the run position the red & purple wires are connected.
This allows the alternator ( purple wire ) to power everything on the mower and recharge the battery.
Thus a bad connection or short anywhere in the system will cause both wires to get hot.

Now if you disconnect the 3 wire plug from the recti-frier , run the mower & the circuit breaker does not pop then the recti-frier, or the wiring to it are suspect.
The Kohler manual has instructions for checking the resistance of the stator to determine if it has a short.
The fact that you are generating electricity means that the circuit is complete but does not rule out a short.

Not shown in the wiring diagram is the full ground circuit.
You need a + & a - or you get no smoke in the wires.
The recti-frier uses it's case to make the - connection but as it is mounted in a plastic blower housing you it needs a wire to connect it to the ground.

This is done with a metal strap to one of the rectifrier mounting bolts.
This strap breaks so the ground paths has to ARC across the crack making it an arc welder & drawing a lot of current, thus making the wires hot.

Te recti-frier has 6 diodes ( or the solid state equivalents )
Four convert the AC to DC and the other 2 send any voltage < 9 V or > 15 V to ground as a direct short.

Finally I have made the assumption that you meant 42 V AC between the white wires and not 42 Amps
 

pgee

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  • / Faulty Stator Causing Electrical Short Tripping Breaker??
Many thanks for taking the time to reply with such clarity.

Yes, you are correct, I did mean to say 42 volts.

Yes, the two wires coming from alternator/stator reflect a short to ground when I tested them. The regulator/rectifier is grounded by wire, not strap, and it appears to be making good connection.

I understand the phenomenon that you say regarding an insufficient path to ground at the regulator/rectifier causing the high draw and hot wires: "This strap breaks so the ground paths has to ARC across the crack making it an arc welder & drawing a lot of current, thus making the wires hot." Is it correct then to say that a shorted alternator/stator, everything else good, could cause the arcing effect when connected to the regulator/rectifier, causing hot wires, and tripped breaker? If so, then a faulty stator must be the problem. Or the short could be in the wires coming from stator.

Are you able to explain how a shorted stator or stator wires, otherwise properly generating electricity, when connected to regulator/rectifier, causes the hot wires/tripped breaker? Not wanting to overdo this, and not arguing, but just trying to reconcile in my head. If we have a stator that is properly generating 42v and the regulator/rectifier works properly to convert to DC then why is purple wire shorting? Maybe I'm overthinking it, and if I am thanks for indulging me.

Bottom line it seems is that I need to replace the alternator/stator.

Thanks,
Paul G
 

bertsmobile1

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  • / Faulty Stator Causing Electrical Short Tripping Breaker??
Many thanks for taking the time to reply with such clarity.

Yes, you are correct, I did mean to say 42 volts.

Yes, the two wires coming from alternator/stator reflect a short to ground when I tested them. The regulator/rectifier is grounded by wire, not strap, and it appears to be making good connection.

I understand the phenomenon that you say regarding an insufficient path to ground at the regulator/rectifier causing the high draw and hot wires: "This strap breaks so the ground paths has to ARC across the crack making it an arc welder & drawing a lot of current, thus making the wires hot." Is it correct then to say that a shorted alternator/stator, everything else good, could cause the arcing effect when connected to the regulator/rectifier, causing hot wires, and tripped breaker? If so, then a faulty stator must be the problem. Or the short could be in the wires coming from stator.

Are you able to explain how a shorted stator or stator wires, otherwise properly generating electricity, when connected to regulator/rectifier, causes the hot wires/tripped breaker? Not wanting to overdo this, and not arguing, but just trying to reconcile in my head. If we have a stator that is properly generating 42v and the regulator/rectifier works properly to convert to DC then why is purple wire shorting? Maybe I'm overthinking it, and if I am thanks for indulging me.

Bottom line it seems is that I need to replace the alternator/stator.

Thanks,
Paul G

Electricity flows in both directions.
The alternator can not generate enough AMPs to blow the breaker
The battery OTOH is a box full of AMPs and can supply in the order of 500 A ( for a short time )
This is why they fuse the battery and not the alternator.

A short in the stator is the same as a short directly across the battery.
The only thing stopping this are the diodes in the rectifier and if one is duff then the battery will try to melt the stator wires when the stator is in circuit.

Mower electrics are very cheap and the diodes in the rectifier are only just cable to keep up with normal generating and there is no high capacity back flow diode as you find in a car alternator.
Unless you are using an ossiliscope to look at the waveform of the alternator out put & the rectifier output you will not pick up a single blown diode in the rectifier.
The alternator pulses every time a magnet passes by a coil in the stator.
There are 36 ( I think ) magnets so if you are using a single coil stator then you are getting 36 x 3500 pulses a minute, way too fast & short for any meter less than $ 1000 to measure.
Generally the coils in the stator are wired in pairs so if you have 24 coils then you will be getting 12 x 36 x 3500 ( engine speed ) pulses a minute.
Your meter reads 42V but in reality you are getting 0v to + 21v to 0v to - 21v.

In a system where the stator is grounded a shorted stator will still work, however the out put will be reduced to reflect the smaller amount of windings being exposed to the magnets.
However the output will have 2 parts,
One will go to the rectifier as normal ( but reduced )
the other will be a direct short to the engine and just get hot.

I seriously doubt that the stator is bad.
They rarely give any problem other than the ground wire ( or wires ) breaking.
OTOH rectifiers cop a beating and regularly go bad.
 

ILENGINE

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  • / Faulty Stator Causing Electrical Short Tripping Breaker??
Quick short test for Kohler stator. White wire to white wire with ohm meter is .1-.2 ohms. Red tester lead to white stator wire and black tester lead to engine block or other good engine ground should show infinity. If fail either test replace stator. Also your engine used the 15 amp regulator/rectifier which is actually a half wave rectifier.
Seems like I tested one some time back and found that the B+ terminal is actually wired directly to one of the terminals on the regulator that connects one of the white stator wires. Seemed strange but the regulator passed testing with the Kohler regulator tester.
 

pgee

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  • / Faulty Stator Causing Electrical Short Tripping Breaker??
Testing stator again and rechecking wiring for the umpteenth time led me to conclude that it was the stator acting up so I spent most of the day pulling engine and getting to the stator. Hope I can get it all back together correctly. Reluctantly I will broadcast what happened.

There was a bolt lodged between the stator and the engine wall. It was causing intermittent problems whenever it was positioned to short out winding. The bolt also wore out the contact on one winding. And one of the magnets on the flywheel was broken into two pieces. Here is why I earlier said reluctantly. About 7 months ago I was troubleshooting the carburetor when one of the three bolts that hold the breather in place dropped out of sight. I looked for over an hour with light and magnet probe but could not find it. This was the bolt that found its way in between stator and cavity wall. What are the odds.

Stator, without the bolt, actually tests good but will still replace it. I hope it comes with a new three prong plug as my shop vac sucked the old plug up after I removed the two stator wires and one purple hot wire.

Regarding the flywheel, I sure didn't want to replace it but I will because the magnet is broken. I do not believe I will be able to find replacement magnets. Actually only need the one magnet.

I will also replace the coils while engine is apart.

I have heard there are better ignition modules than what I currently have in the 2003 Kohler 64554. When I look up parts it gives me two choices: PN 2458445S identified as CDI Fixed which is what I think I currently have. The second PN is 2570703S which is MDI Module Conversion. Not sure which one I should buy. Also, the current coils were installed differently: left as I face it had the kill wire in the back and the plug wire in front while the right side was opposite with kill wire in front and plug wire in back.

Last question is whether their is a particular stator that is better than the other. OEM vs aftermarket?

I am new to this forum and such posts so if I am overreaching with the questions regarding parts just say so.

The responses from both of you have been a great help to me and I greatly appreciate it. And perhaps the posts will help someone else.
 

bertsmobile1

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  • / Faulty Stator Causing Electrical Short Tripping Breaker??
Same reply I gave to another.
look up the yellow pages for a mower repair shop.
They will have boxes full of old alternators and flywheels pulled from engines that seized or threw a rod
When I bought the business 4 years ago I had only 1 old B & S one in stock.
I now have a box full of B & S alternators & 5 Kohler Courages.
If I had been doing this for 20 years there would be crates of them.

After that I fit mainly pattern parts BOUGHT THROUGH MY PARTS WHOLESALER and never off the web.
Thus I can give customers a good price and a warranty.
 

ILENGINE

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  • / Faulty Stator Causing Electrical Short Tripping Breaker??
Stay with the fixed CDI ignition. Because trying to convert to the MDI can get complicated and cause performance issues. At a minimum would require the flywheel for the Spark advance system. But there could be more involved. At our Kohler dealer meeting they tell us not to attempt it because it may not work correctly. Also the modules are installed correctly One faces up and the other down.
 
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