312-8 with K301 not charging

[TC10284 118]

I have, I think, a 1985 or 1986 312-8 with K301. The model on the tractor is worn off. 

 

I took the flywheel off this afternoon and tested resistance and I am getting infinity resistance at the connector, and even when piercing the wire jacket directly on both yellow wires. All the magnets are on the flywheel properly and a wrench will stick to the magnets. 

 

Is this a 3amp stator? Is there a part number I can look up for a replacement? 

 

Also, for my own knowledge, how is the spark plug firing like this? I know this guy has points on it. Only one wire going to the coil. 

 

Pictures:

https://photos.app.goo.gl/61BHYDfJfh1ChoVFA

 

 

[953 nut 68,530]

here is a simple drawing to help you see how the spark system is wired using a 103990 battery ignition switch. All of these components needs to be grounded to operate.

[TC10284 118]

1 hour ago, 953 nut said:

here is a simple drawing to help you see how the spark system is wired using a 103990 battery ignition switch. All of these components needs to be grounded to operate.

 

 

I guess it was running off the battery then and not being recharged by the stator/diode if I'm reading that right. 

[gwest_ca-(File Mod) 12,457]

Will the headlamps work without the engine running (15amp regulated) or does the engine have to be running supplying AC current to run the headlamps (3amp)?

[TC10284 118]

12 minutes ago, gwest_ca said:

Will the headlamps work without the engine running (15amp regulated) or does the engine have to be running supplying AC current to run the headlamps (3amp)?

 

Has to be running for them to work. 

[gwest_ca-(File Mod) 12,457]

No low oil switch in the rear base of the oil pan = 1985 model Kohler spec # 47812

If you have a low oil switch in the rear base of the oil pan it is a 1986 model - Kohler spec # 47828

[TC10284 118]

1985 since my engine spec is 47812 on the sticker (from my pictures link). 

[953 nut 68,530]

 

11 hours ago, TC10284 said:

 

I guess it was running off the battery then and not being recharged by the stator/diode if I'm reading that right. 

The stator will recharge the battery, your ignition coil needs a wire from the "-" side going to the ignition points and condenser and a wire from the ignition switch to the "+" side to produce spark.

Here is a wiring system guide for your , it has each system including the ignition shown sepertely.

 

[TC10284 118]

Thanks! You are always very informative!

 

At this point, I just need to find out if I can get the 3 amp stator rewired or if I should get the 15/20amp stator with regulator kit.

If so, does anyone have any advice on placement of the regulator so it can get cool air? I don't want to cut a hole in the shroud and hate to put self-tapping screws in also, but I may have to. 

[pfrederi 21,051]

[pfrederi 21,051]

3 amp stator is 45 085 02

[953 nut 68,530]

39 minutes ago, TC10284 said:

advice on placement of the regulator so it can get cool air?

You would need to use a Regulator with larger cooling fins.

[ineedanother 2,809]

On 9/8/2026 at 8:11 AM, TC10284 said:

Thanks! You are always very informative!

 

At this point, I just need to find out if I can get the 3 amp stator rewired or if I should get the 15/20amp stator with regulator kit.

If so, does anyone have any advice on placement of the regulator so it can get cool air? I don't want to cut a hole in the shroud and hate to put self-tapping screws in also, but I may have to. 

If you just need a stator, this is in my garage. If I remember correctly it's in need of a valve job that I'll likely never do but it ran when parked . PM if you're interested in the whole thing. Free to a fellow southerner!

[TC10284 118]

I am confused. 

I tried to run through the stator tests posted above. Measuring across the battery I get battery voltage of 12.4v when the engine is not running. Same 12.4v when it is. 

 

Test 2, how do you even test for that if you can't disconnect the charging lead without killing the engine? The only way is to disconnect the yellow a/c wires from the main connector. 

 

The diode tests good. 

I can see the headlights get brighter or dimmer with throttle. So I know at least part of the stator is working. 

 

If Iconnect a known good diode to the yellow wire from the stator that is supposed to charge the battery, I see a maximum of 10v at WOT and 8v at idle. 

 

If I swap to the other yellow wire that is supposed to run the headlights and temp put a diode on that wire, I get at most 10v at idle, and the voltage actually drops to 9v at WOT. 

 

Edited 19 hours ago by TC10284

[pfrederi 21,051]

Pull the R wire from the back of the ignition switch and measure that to ground

Edited 19 hours ago by pfrederi

[TC10284 118]

I will try checking the R wire on the ignition switch next time I work on it. 

 

Before seeing your reply, I put a NOS 3amp stator on it (correct Kohler p/n for this engine) that I bought and the voltages look way better. But when I'm idling with the diode temporarily inserted into one of the stator leads, I was seeing around 13v DC. But when I move to WOT, I see way higher voltage of 20v to 30v. And this is a new diode.

 

Maybe that's OK if it's half wave rectification? 

Edited 2 hours ago by TC10284