No Spark--Comes and Goes

[LBarnes]

Hi guys...brush hogging with my 8N and she died in the middle of my pasture. Determined no spark. Cleaned points and she started right up. Went a lap or two more and she died again. Installed NEW points and condenser and she started right up. Went a lap or two and she died again. Installed a new coil. Did NOT start this time and it got dark. Going back out in the pasture today to revisit. If it's not the points and condenser and it's not the coil, what should I check and/or replace next? It's a side mount distributor (thankfully) and it's still 6 volt, so there's no ballast resistor, battery is good. There was 6 volts going in and coming out of the coil and at the points, but it goes away, leaving no spark. Something gets hot? I doubt that because it happens after several laps at the same speed and operating temps, and doesn't restart when it cools off. Anybody got any ideas?


Larry in Ohio

 

[R Geiger]

Bypass the ignition switch and give it a try. they go bad.

 

[Jim L WA]

You shouldn't see 6 volts coming out of the coil unless the points happen to be open. Check the wire from the coil to the distributor. Then check inside the distributor for an open circuit. I'm leaning toward that wire, because when you disturbed it, changing the coil it won't start at all now.

 

[Bruce (VA)]

One of the earliest lessons I learned working on old cars was never to replace a part until I confirmed it was defective.

It's apparent that the new points. condenser and coil were not the problem.


That's getting pretty expensive and time consuming.


So it's best to troubleshoot the problem before you replace the parts.


Got a multimeter? Set it on volts and follow the volts from the battery to the points.

Confirm that you have voltage to the coil. Battery voltage, points open. About half that if the points are closed.



Do you have battery voltage across the points when they are open? (with the points open, put one probe on one side of the points & the other probe on the opposite side of the points) Verify the gap on the points at .025. Then, dress the points by running a piece of card stock or brown paper bag through them. New points sometimes have an anti-corrosive dielectric coating on them & old points can corrode or pick up grease from a dirty feeler gauge or excessive cam lubricant. (I always spray my feeler gauge blade off w/ contact cleaner.) Make sure you have voltage across the points, as in past the insulator on the side of the distributor. That is a very common failure point on sidemounts, along w/ the attached copper strip. It's hard to find a short there because it is usually an intermittent . So 'wiggle' the insulator & the copper strip a bit when you are doing your checking. If you find the short there, the Master Parts catalog lists everything you need on page 154. You can make the strip and you could also make the insulators as well. But, somethings are just easier & in the long run cheaper to buy. Get the strip, 12209, screw 350032-S, 12233 bushing & 12234 insulator & just replace it all.
75 Tips

 

[RM-MN]

I've had a ammeter go bad and give me intermittent spark.

 

[Tony292]

Check your coil and ballast resistor. My ballast had a lot of rust on it and I couldn t get a good reading with the multimeter numbers just kept jumping around. Both are dirt cheap and easy to check, keep whatever is good for spares.

 

[Tom Massachusetts]

(reply to post at 10:22:31 06/01/19)

think the old coil was bad, getting hot and quitting. The new coil may be defective or could be a 12V coil.
Ran with the old coil till it got hot. The new coil did not run at all.

 

[LBarnes]

Hi Guys and thanks for the help. FYI, I changed the points, condenser and rotor, which did not fix it, then the coil, which did not fix it, then the cap which did not SEEM to fix it. So then I cleaned the new points real good and it started running good and I finished brush hogging which took a couple of hours. So I'm not sure what actually healed it. Like Bruce says above, "determine for sure which part went bad before you replace it." But I did it all step by step. My theory is that it WAS the coil, but the NEW points needed cleaning again. I hadn't cleaned them since they were brand new. But that's just my theory...

Thanks to the last cowboy, Tony292, cersbo, JMOR and Hobo,NC

Larry in Ohio