R with no spark

brian(MN)

Member
I have been working on these engines for years and this one has me stumped. I bought an R last fall, owner really had to pull it to get it going. I hauled it home and got busy. By winter time It would not start so I pushed it in the shed. It won't start now-no spark. I have been chasing electricity around, switch works , current to the coil and to the points. No spark. I tried 3 different coils, including a new one, no change. I put in new points/condenser/rotor-nothing. I tried another coil wire-nothing. If I had another cap here, I'd try that. Am I over looking something? The problem has to be in the high voltage circuit. I know this tractor ran good years ago when it was at my plowing bees, but it has not been used lately, so it has been neglected for 7 years but it has been in a shed. The tractor has a good paint job and new tires but sure could use new wiring. These old tractors are fun? Brian
 


Is there a spark track inside the distributor, or any were else the spark maybe jumping? Are you getting spark to the points while cranking it over?
 
Inside of the distributor cap looked OK, but I did not look at it close up under light. What would a spark track look like? Not so sure if there was spark at the points while cranking. I cranked it with the battery and by hand and there was no difference. I'd like to try another cap. Come to think about it, the old rotor metal spring top was bent sideways, I put a new rotor in. Brian
 
Just an idea, worn bushing on the distributor shaft? It should still run with that though. When I worked at a shop in town there was a guy that came in with a U that would not run worth a darn. Bushing was worn in the distributor. Got it fixed and it ran good after that. Also, didn't some of the R-Z engines some times shear the key off the drive gear in the oil pump. That might be a far stretch though but, if all else fails...another place to look.
 
Even new condensers are bad. "Speaking from experience" Another place to check is the stud that goes through the distributor too. On my 5 star gas it was jumping spark there. As it turned out the black plastic insulator was was cracked.
 
Use a DC volt meter or a test light. You should see battery voltage at input to the coil

Check voltage at wire between coil output and side post on distributor. Should be battery voltage (or light on) with points open and zero voltage (or light off) with points closed.

If near battery voltage or light on with points closed, check for broken connection or points not making good contact.

If near zero voltage or light off with points open check for something shorted between distributor input and points ground.

Is this original 6 volt or is it a 12 volt conversion?
 
(quoted from post at 21:21:59 03/10/15) Inside of the distributor cap looked OK, but I did not look at it close up under light. What would a spark track look like? Not so sure if there was spark at the points while cranking. I cranked it with the battery and by hand and there was no difference. I'd like to try another cap. Come to think about it, the old rotor metal spring top was bent sideways, I put a new rotor in. Brian

A spark track will look like a lead pencil line. The spark will follow it to ground. Or a crack.
 
Well, the sun, the moon, and the stars must have lined up just right because I got this R started last weekend. I replaced everything 2-3 times, finally started and ran fine, even charged. So I replaced the original parts back one by one because I wanted to find out exactly what the problem was. They all worked! ( I don't have any hair left to pull out) I figured it was the old wiring so I re-wired the whole thing last Sunday, runs fine but does not generate now. The old wiring was pretty crispy. I have yet to check all the connections and maybe that old original light switch is not making contact like it should. Isn't working on old tractors fun?
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top