Cap and or Roter Failure?

[tinnerjohn]

Wondering if anyone has experienced suddenly losing spark because these two were bad? My Cub was running fine, cultivating at low idle, then suddenly shut off, I am getting gas but doesn't seem to be getting spark. I have no idea how old the cap and rotor are but when I checked them they definitely need replaced. The points are fairly new, they look good. Just wondering if anyone has had this happen? Naturally the tractor is in the middle of the yard, didn't die under a shade tree so further troubleshooting is going to wait until the sun isn't overhead! At least it not in the middle of the garden or the back corner of a 40 acre field where they usually pick to die!

 

[Jim Becker]

They usually don't have an abrupt failure but gradually deteriorate until "suddenly" they won't let the spark pass. There are exceptions, like when a carbon track diverts the spark to a nearby ground. Since you were working at a low idle, my first guess would be fouled spark plugs. In any case, do some diagnostics to isolate the problem. Check for a healthy spark at the coil wire. If so, then check at one or more spark plug wires. If poor there, look into the cap and rotor. If good there, follow up on the spark plugs.

 

[Farmallsodbuster]

I have not on a tractor but I was driving a Chevy truck that died going down the road and was a cracked distributor cap. If the switch is left on for a lengthy period without the engine running it can burn the points. Also wiggle the coil wire around a bit to a new location. The coil wire can sometimes short to something and kill the spark before it gets to the cap. After dark is a good time to spin the engine over and see if you see sparks shorting from wires to ground. You didn’t accidentally bump the switch and cut it off while driving maybe.

 

[staninlowerAL]

My 57 LoBoy was starting and running fine, no problems at all when one day I attempted to start it and no go. Spark at the points but no spark at the coil output to distributor cap center tower. My problem turned out to be a bad coil. Jim Becker's advice will settle that issue. If no spark to the plugs, next make sure that the points are firing. JMHO Stan

 

[tst]

coils go bad, quick test when it dies is it really Hot ?

 

[yellowcub]

Yes, I had that same thing happen, points went bad so I just replaced them rather than file. Also, had rotor and cap get some corrosion so every year new rotor and cap.

 

[tinnerjohn]

I'm going to pick up a new cap and rotor tomorrow, hopefully I can get one with brass contacts, the old one is aluminum and badly corroded.. Its probably overdue for plugs so I'm going to get them also. I haven't done anything to it yet but will post what I find when I dig deeper. Farmallsodbuster's mention of the wires reminded me of a Ford Van that started running rough coming home from work in the rain. Opened the hood and it looked like a lightening show between several plug wires and the block!

 

[Bob McCarty]

Napa has the cap with copper contacts, if you have one close.

 

[tinnerjohn]

Thanks Bob. I knew they used to but wasn't sure nowadays.

 

[I gotta cub]

Does your cub operate on a coil, or a magneto?

 

[inairam]

I have had multiple cubs die suddenly from the spring breaking on the points. Even OEM points and other ones from the Tractor websites. I switched to NAPA and have not had ignition problems.

Napa part numbers.
napa points ECH CS1600
napa Condenser ECH IH200
napa Rotor ECH IH300
napa Cap ECH IH350
napa Plug CHA 549 D18Y ( projected) CHA 502 ( non projects)D21
napa oil; filter 1153

 

[NJ Farmer]

If you have an original coil I’m going to be that the coil went bad. If the tractor runs good cold but when it gets hot it starts loosing spark your coil is shot. The heat breaks down the continuity in the windings and the resistance increases therefore the spark voltage decreases.

Ask me how I know…..

NJ Farmer

 

[I gotta cub]

If it is a magneto setup, it could be a as simple as a broken/loose wire.

 

[Waif]

I have replaced a magneto system coil in the field. Prior warnings were the system conking out when hot ; then restarting after the coil cooled. (Overnight to cool is more sure than a couple hours.) Two occurrences if recalled correctly before changing it.

.
Antifreeze in a cap on a vehicle from a blown hose I worked on nulled the cap rotor relationship.
It would be oil on a Cub probably doing anything similar.
Dressing the rotor metal edge very lightly to clean it and a mild surface cleaning of cap contact terminals risks creating too big of a gap on very worn or very corroded parts. But can be a desperate measure while awaiting parts on a stopped engine.

 

[52DAVE]

I had a car years ago that the condenser went bad on all of a sudden. It ran fine and all of a sudden no spark. Also I was using my dads SA once and the condenser suddenly died. I now keep a spare one in my tool box .