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Subject: 8N Starter Problems

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Dan Mayer    Posted 09-15-2018 at 10:11:24 [URL] [DELETE]        [Reply] [Email]  
  • 8N Starter Problems
  • At wits end with a 1950 8N. The starter seems to be grounded sometimes but sometimes not. I've pulled the starter and bench tested it and it spins great. Installed it, and it cranked a few dozen times, and then just stopped. Now it won't crank at all. Solenoid clicks but no starter. Jumper from my truck will spark at the starter housing, but nothing at the stud. It seems like the grounding path has been interrupted somehow, but I don't understand how it could change while it's still bolted to the tractor.

    Dan Mayer    Posted 09-16-2018 at 19:47:16 [URL] [DELETE]        [Reply] [Email]  
  • Running
  • It's running again. I pulled the starter, put the original armature back in it, shined up all the surfaces. Replaced the undersized battery cable. Topped off the battery on the tender and she started right up. I had the bendix off so this was the first time I was able to wire brush the surfaces on the plate that covers the block end of the starter housing. I think this might have been the bad connection. Or it could have been the undersized battery cable. Either way it's starting like a champ now.

    Tim Daley(MI)    Posted 09-16-2018 at 03:45:47 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N Starter Problems
  • As Bruce has stated, when a solenoid just 'click, click, clicks', it is usually due to a dead or near dead battery. Are you running a 6V/POS GND system or a 12V switch job? Do you have a front mount distributor or the angle mount? You can jump start a 6V system with your 12V truck battery but you need to know how to do it right. Download a copy of Bruce(VA)'s '75 Tips for N-Owners' and keep it handy for reference. New, low-cost batteries can often be junk out the door from your local auto parts store too. Be certain you are using the correct battery for your tractor. A 6V type is a GRP-1 and a 12V type is a GRP-25 or GRP-35 battery. Avoid automotive, Deep Cycle, golf cart, and lawn mower batteries. Battery cables are also important. 6V requires heavier gauge than 12V- thick as your thumb style. The battery ground is best done using the OEM style braided strap -see attached LINK. You can take the battery and the starter to your local starter/alternator shop and they will bench test them, usually at no charge -pun not intended. A battery must sustain a full charge under load in order to perform successfully. While the shop is testing your components, go thru the entire wiring system and verify it is correct, whether 6V/POS GND or 12V/NEG GND. 99.98% of all non-starting/non-running issues are due to incorrect/bad wiring regardless if 6V or 12V. Your initial statement, "The starter seems to be grounded sometimes but sometimes not" would indicate something is not wired correctly. First, I'd disconnect the lights just to take them out of the equation. You can reconnect them later once root cause problem is determined and fixed. Go to our HOW-TO's forum, under ELECTRICAL and download a copy of "WIRING PICTOGRAMS BY JMOR" then find your set-up and use as a guide for your wiring system with no deviations allowed. You are on the right path so far, just need to make a few more basic tests. The battery and cables, then wiring system are primary concerns.

    Tim Daley(MI)

    Bruce (VA)    Posted 09-15-2018 at 11:42:43 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Starter Problems
  • " Solenoid clicks but no starter."

    The solenoid is making a noise because of low voltage. That is likely caused
    by:

    1. A weak battery (charge it & check it per tip # 49. Or get it load
    tested.)*

    2. Dirty grounds/connections (remove the cables & clean the connections)

    3. Bad cables or incorrect sized cables (replace them - see tip # 41)**

    4. Bad ground between the starter & the block. (pull the starter away from the block & clean the mating area - see tip # 36)


    Yes, you could have a defective starter, but you need to check the most likely causes of your problem and eliminate them from the equation: the battery and connections.


    Jumper cables aren't an effective way to test a defective starter or battery.


    ** You can't see corrosion under the insulation.


    Dan Mayer    Posted 09-15-2018 at 17:38:48 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Starter Problems
  • OK, I've been working on this a while and have tried some of the things on your list.
    1. New Battery, stored on tender, reads 6.3 volts, so I think I can rule that out.
    2. I've cleaned every contact surface I can find, including the starter face and mating surface on block.
    3. I've noticed that the hot cable to the frame is smaller than the negative cable. It could be a factor, but it has started before, and wouldn't affect a jump start straight to the starter, right?
    4. Bad ground between starter and block. I assume that since I can draw a spark off the starter housing with the jumper cable, that it's well grounded to the frame. Maybe I'm wrong.
    Could a worn-down commutator cause this problem? I have two starters, the armature in there now came from an older starter that had lots of copper filings in the housing and some wearing on the commutator surfaces. I only put it in because its bendix wasn't extended like the other one, and it was a lot easier to get in place. Maybe I need to work on retracting the bendix on the better armature?

    Bruce (VA)    Posted 09-15-2018 at 18:07:21 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Starter Problems
  • " 1. New Battery, stored on tender, reads 6.3 volts, so I think I can rule that out."

    Nope.

    Not at all.


    Check out tip # 49.

    What was your hydrometer reading? A dead cell will easily show 6.3 volts across the posts.


    Incorrect sized cables aren't helping your problem one bit. See tip # 41.

    " 4. Bad ground between starter and block. I assume that since I can draw a spark off the starter housing with the jumper cable, that it's well grounded to the frame. Maybe I'm wrong." Yep. Seeing a spark does not assure you of a good ground.


    Bottom line....test the battery. Take it to the parts store for a load test or buy a hydrometer.

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