Kohler toasts coils.

[simple_gifts]

A friend of mine has a CC with single cyl. Kohler engine. vintage 1983. It has toasted 4 coils in 4 years, the latest lasting about 3 weeks. Failure has been an open on the coil.

Talked to the small engine guy, he indicated if the key switch is bad (like still on when turned to off) and the points are closed, the coil gets cooked. He replaced the most recent coil for free, and I tested coil/ground when the switch is off and there is no voltage. (not sure how to check if the points are closed; I don't even know where they are)

Questions are:

Is there any other scenario that can cause coil failure?

Should coils fail this regularly on OPE This machine VIBRATES (1 cyl) and the coil is under the hood which I imagine runs hot.

Thanks

-Thomas

 

[dwendt44]

Coils need a decent air flow around/over them or they'll fail from heat.
If there's room, longer screws and some washers under the coil to isolate the coil from engine a bit.
Might consider a different brand of coil will fit/work.
Ask if this is a common failure.
Good, clean ground?

 

[Bill Kapaun]

Often, old battery/point ignition systems had a ballast resistor. Typical automotive before electronic ignition.
This resistor, to the coil from the battery, was bypassed while cranking.
The idea is that a coil designed to operate on 12V, won't get enough V when cranking the engine because of V drop.
Therefore, the coil is designed to operate at around 9V, which is about what the battery drops to when cranking.
In normal "run" mode, the coil + feed has the resistor in series to drop the V to it's nominal 9V. The resistor is bypassed during cranking with a "jumper" connected to a "special" terminal on the solenoid that only has battery V when the solenoid is engaged.
Now I don't know if that model & engine have such a system (since you failed to provide any numbers).
BUT- IF it didn't, AND if the coil was replaced with a std. automotive coil, then that is the likely problem. You need to add a resistor, such as found on late 50's Chevys.

 

[Bill Kapaun]

Forgot to add-
OR get the proper coil.

 

[simple_gifts]

Well, coil may be shot again; it is a Kohler coil. Machine is CC Hydro 630; I don't know the Kohler engine #, but it is 1 cyl. Will be stopping by the tractor place again; perhaps the ballast resistor B.K is referring to is shot and coil is getting 12V all the time. I only see this thing once or twice a year so I will have to check to see the starting setup.

 

[Lazy JW]

If this is a battery/coil type ignition it can be modified to take a Ford TFI ignition module to fire a TFI or GM HEI type coil using the the points to trigger the module for correct timing. The points will then last almost forever and the module controls the coil circuit. Check out http://www.gofastforless.com for details.

I have a Kohler 7 hp on a tiller that ate the coil; it is a magneto type. Installed a Bosch VW coil and a Makita 9.6 volt battery for a total loss ignition. It uses the original points; need to charge up the battery before running the tiller.

I already had a junk Makita drill (broken) to use for the battery holder. I had replaced the original coil once last year to the tune of $90 so built this setup using stuff I already had laying around.
Joe

 

[JTK]

Sounds like an old bullet proof Kohler K-series? We had one in our 1970 John Deere 110. Never replaced the coil in the ~28yrs we owned it.

Joel

 

[simple_gifts]

update: stopped by yesterday with my multi-meter and turns out the coil is still good; seems to be a case of a simple broken wire; (she did not lift the hood and do a visual apparently)

This mower is a beast; built for decades of serviceability. Sounds like a WWII fighter when it cranks and starts.

 

[Lazy JW]

My last set of brand-new points from Kohler was bad right out of the sealed plastic package. My Fluke 88 meter read Infinite resistance when on the 400 Ohm scale, had to go up one scale to get continuity to indicate. Had to file them before they would work (I use a little diamond hone of the type made for sharpening knives; made by Ez-Lap®)
Joe