Smoking Coil

[ajtimm]

So I have a cub 100 that didn’t start and I pushed to the side until I could work on it. Now when I turn the key on and turn over the motor,

the coil starts smoking.
Any suggestions besides replacing coil and points?

Thanks

 

[mgwin]

Double check your wiring and take the coil wires loose and ohm it out. Check the points too. Take the cover off of the voltage regulator and check it also.

 

[ajtimm]

Another picture-
Never had this happen before…

 

[jkoenig]

Great photos! I've never seen that either, and would have had a hard time believing it was that impressive.


\/ Yeah, you're not suppolsed to let that out.

 

[1811Cub]

The magical smoke has escaped...

 

[lpalma]

Time for a new one, voltage regulator has no bearing on the coil, you can disconnect the wires to it and you can still run it, but the battery will go dead eventually.

 

[jlord]

Is there supposed to be a ballast resistor in series with the coil to limit the current through the coil like cars and trucks do?

I have a 1982 Dodge D-150 w/ a 225 cid "slant 6 " in it. It has a ballast resistor as described above and a relay that shunts out the resistor so you get full current / voltage when the starter is cranking. This is because available voltage is much lower from the battery when the starter is cranking the engine.

Might be a possibility here. I would do an ohms reading through the coil to make sure its within specs. Not sure because it can vary, but I think it should be about 4 ohms.

However, once the smoke is let out, all bets are off and the coil is almost certainly damaged

 

[dschwandt]

Make sure you get the correct replacement coil for this app and not an automotive coil.
All coils are NOT created equal!!
Check here
FAQ #21
http://cubfaq.com/tuneparts.html

 

[mgonitzke]

Does it say "external resistor required" on the outside? If so, that is the problem. You either need to add a ballast resistor or get the proper coil that does not require one.

 

[tkhoffman]

I wonder if the wires from 5th he battery are getting hot too. Maybe moisture got in the coil causing a short that is heating up the oil in the coil?

 

[jherdebu]

I had one that would get super hot not smoking, just to hot to touch. I swapped the coil out with coil from the Kohler on my John Deere. that got super hot too. Went thru wiring bad ground connection at the engine block. Replaced with new 8 gauge cable. Everything running cool and amp gauge reading better as well

 

[ajtimm]

First thing I did was order new coil, ducer II and points from Kirk. Not sure why the coil would smoke but I will ohm the coil and report if I can find any other anomalies. Thanks!

 

[dschwandt]

Good grounds, clean tight connections and terminal connectors are very important areas that merit attention on these or any other machine as well.

 

[ajtimm]

New Kirk Transducer II, Coil and spark plug Wire. Started first turn. My 11-year-old is driving circles in the driveway now.

 

[tkhoffman]

Curious as to what the inside of the old coil looks like.
Any bubbling paint on the casing(from heat)?

 

[Colton Stevens]

So I have been running mine with an automotive 12v coil without a resistor for a while now. It definitely gets hot but never smokes. I know that it "needs" it, and I know it can damage the points, but I also know it makes more power this way. Hot rodders the resistor out often to make better power, but usually keep an extra coil in the glove box in case it burns out. I figured mine would have burned out by now, but it is still going, and starts very nicely. I'll keep running it and see how many hrs I can get out of an unresisted automotive coil.

 

[mfrade]

So I have been running mine with an automotive 12v coil without a resistor for a while now. It definitely gets hot but never smokes. I know that it "needs" it, and I know it can damage the points, but I also know it makes more power this way. Hot rodders the resistor out often to make better power, but usually keep an extra coil in the glove box in case it burns out. I figured mine would have burned out by now, but it is still going, and starts very nicely. I'll keep running it and see how many hrs I can get out of an unresisted automotive coil.

It could be that it has an internal resistor.. Like the Delco units originally used by IH Cub Cadet

 

[jdrong]

From what I remember, early cars, etc. only needed an external resistor when using a 6-volt coil in a 12 volt system. The 6 volt coil got the full 12 volts when cranking to start. Once the engine started and the starter/key switch returned to run, the 12 volts ran through the resistor reducing the voltage to 6 volts and then to the 6 volt coil. Once 12 volt coils were used, a resistor was no longer necessary. Further proof of this, if the resistor burnt out, the car would start normally but, when the key switch was allowed to return to run, the engine would stop. Other than normal wear, the only time a coil or points would "burn up" is when the key was left turned on with engine not running and the points were closed.

 

[dfrisk]

My Dad gave me 3-4 supposedly "good" coils that he had removed from running Cubbies's to the best of his recollection. I had nearly new coils on both my mowing tractors, it was interesting, on a cold start I could mow about a half hour and the tractor would die. Leave it set 30 to 45 minutes and you could mow another 20-30 minutes. I had small internal shorts in both coils. I didn't want cheap farm/home store coils. DAVE KIRK wasn't selling his Bosch blue coils yet but I did find a "Kohler" coil and they solved my engine problem and ran for years.
Best thing was when I put one of Dad's old coils on the K-181 engine on my lawn vacuum, just ran a 16 GA wire from the battery of the 72 to a in-line on/off switch and back to the coil on the K-181. The first coil lasted about an hour and died. Put another used coil on, engine ran 30-40 minutes and I look behind me at the K-181 and there's scalding hot oil gushing out the top of the coil and eventually the engine died. Look carefully at a coil and they emboss them with "Oil Filled" on the can, obviously that second coil had a short too. This time the K-181 needed another NEW coil, and new points & condensor. I haven't used the lawn vacuum in 10-12 years but it's sitting in the shop and I'm sure it would start and run in a few minutes if I hooked up to it.
I had my 982 sputter and die years ago while mowing and wouldn't restart. The little potted electric box on top right side of engine had a broken wire to one of the three lug terminals. I soldered on a new connector and attached it and it started right up. Yep, makes good sense to mount potted electrical components as close as possible to extremely HOT engine components subject to high frequency vibration also. Makes me like my 27 HP Kawasaki on my Zero turn WAY so much better.

 

[Colton Stevens]

It could be that it has an internal resistor.. Like the Delco units originally used by IH Cub Cadet

Mine says "use with external resister" on the side. It is from a 72 Dodge van. As other's mentioned, Dodge used external ballast resistors going to the coil. It absolutely "should" have an external resistor in line. I think mine is an oil filled one, maybe that is why it has lasted this long. Either way, it has a warranty lol. I still have my cub coil, but I need to test it, I think it got damaged in the garage.
The way I see it, unless the battery blows up, which I think is very unlikely, the worst that can happen is I burn up the coil that has a warranty, or I burn up some 56 year old points, and have to buy another set, for which it was probably due.