312-8 No Spark

[adsm08 4,644]

The guy across the street, who used to do mower repair professionally, recently bought a 312-8 with no spark. He hasn't been able to figure it out, and I have looked at it yet, but I'm not super familiar with the Magnum engines and I'm not real sure where to start.

[gwest_ca-(File Mod) 12,295]

First thing I would do is disconnect the wires between the engine and tractor harnesses. Wires will come out on the back side from behind the flywheel. If it then runs it will not shut off because the ignition wire is not grounded.

A model number and serial number will give us a chance to look at how it is wired.

[953 nut 66,833]

The four wires blocked in red are the two oil switch wires are blue, white for charging and Dark Blue is the one that grounds the Mag to stop the engine.

[Achto 31,981]

Solid state ignition, Either the coil is grounded out or it is bad. 

[squonk 47,038]

Lots of bad coils on Magnums as they age. LOTS! 

Edited May 17 by squonk

[Bill D 2,937]

Just had to replace a coil on an M20.

[adsm08 4,644]

9 hours ago, Achto said:

Solid state ignition, Either the coil is grounded out or it is bad. 

 

1 hour ago, squonk said:

Lots of bad coils on Magnums as they age. LOTS! 

 

55 minutes ago, Bill D said:

Just had to replace a coil on an M20.

 

This is what we are both thinking, but he wanted to do some actual diag before commiting to the cost of a new coil. He prefers to use OEM parts on the tractors, but I can't convince him to stop using Fram oil filters on his cars.

 

 

@gwest_ca I think he did try disconnecting the grounding wire and couldn't get it running.\

 

 

I will go over and try to get ID tags off the unit. It's just sitting out in his back yard, and he doesn't care if I wander in there, especially in situations where I'm helping figure out tractor stuff.

 

I'm pretty sure he said the engine model was a M12S, but I'm not certain.

 

 

 

Edited May 17 by adsm08

[adsm08 4,644]

Engine tag:

 

 

 

 

Tractor model tag was nowhere to be found.

Edited May 17 by adsm08

[gwest_ca-(File Mod) 12,295]

Kohler made seral 18xxxxxxxx in 1988 so two tractor models possible

1988 model 21-12K805

1989 model 21-12K806

 

[squonk 47,038]

Tractor sitting in a yard. Look for a mouse modified coil wire. 

[adsm08 4,644]

19 minutes ago, squonk said:

Tractor sitting in a yard. Look for a mouse modified coil wire. 

 

This just showed up in his yard a week or two ago, I do not know the history of it before that, the no spark was already existing when he bought it.

[adsm08 4,644]

So to update this, after doing the specified tests he bought a cheap magneto, set the air gap, did not bolt the right side of the magneto down properly, cranked it, caught said magneto with the flywheel, and broke the engine end plate.

 

Tractor is currently at the local Toro dealer.