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Ford 9N, 2N & 8N Discussion Forum
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Burning Out front mount 6 volt coils

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beirnem

07-12-2018 09:22:40




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I recently got a 8n tractor with a front mount 6 volt coil. The coils was wired directly from the switch with out passing thru the resistor by the PO and the coil was burned out. I got a new resister from YT and still burned out another new coil. I had 6.48 volts before the resister and 5.45 volts after the resister at the coil. The tractor ran for about 10 seconds then shutoff and no spark. This is the 3rd coil, and I now have a collection of dead coils.
Question 1: What should be the voltage at the coil?

Question 2: what have I done wrong?

Question 3: Is the coil that sensitive?

I'm at wits end. Any help is appreciated.

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Bruce (VA)

07-18-2018 19:04:07




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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Well, that's one option I hadn't thought of!

What do you plan on doing w/ the old one?



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beirnem

07-18-2018 18:56:28




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
Well, I gave up and bought a new distributor. Now the tractor runs great. So it was in the distributed somewhere as you said. Thanks for all the help. I would liked to have known where in the distributed but I have spent way too much time on just this one issue and I have a lot more to do. Thanks all.



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Bruce (VA)

07-17-2018 09:51:05




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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Your clip is positioned correctly. The brass screw is centered in the hole (meaning your timing is probably off a few degrees, but don't worry about that).
" I think as the coil wire gets warm it shorts on the retainer ring"
I doubt that. But...……...if the pig tail is cocked to one side, or more importantly, the coil is not perfectly seated with the correct gasket and does not move at all......then yes, that pig tail will short. Or more likely, will lose firm contact w/ the brass screw. Did you perform this check: 3. Put the coil on the distributor, cap off, points open. One probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!

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beirnem

07-17-2018 09:05:30




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
Bruce,

Based on what you told me I agree that it is in the distributer. I think as the coil wire gets warm it shorts on the retainer ring, and then no spark. If I reseat the coil I will fire. I will attach a picture of the distributer can you tell me if the retainer ring is misplaced and/or it is plausible it may be shorting on the retainer ring?

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beirnem

07-15-2018 18:43:19




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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Yes jumper wire direct, and voltage was 6.42 after cutoff



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Bruce (VA)

07-15-2018 20:13:47




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-15-2018 18:43:19  

" Yes jumper wire direct, and voltage was 6.42 after cutoff "


That means the problem is inside the distributor.


Assuming that the bushings & advance weights are ok (*see below), & that you have correct voltage to the coil , the most common reasons for no spark or a weak spark on the front distributor are below. Check each one carefully. Even if you find a problem, check all 10:

1. The insulator under the brass concave head screw & where the copper strip attaches. (it's fiber & will wear out; poke & prod w/ your meter leads to make sure it still works) If you need to replace the insulator, use a .250 x 3/8 nylon square nylon anchor nut available at most big box home stores.

2. The pigtail at the bottom of the coil not making contact w/ the concave head brass screw inside the distributor. (With the coil on, the pigtail must firmly contact the brass screw. No contact = no spark) Check for continuity between the top of the coil and the pig tail; a 6 volt coil will be around 1 ohm & a 12 volt coil should be 2 to 3 ohms.

3. The copper strip is broken or grounded to the plate. (look very carefully for cracks & breaks) .

4. The distributor is not grounded to the block because of paint or grease acting as an insulator. Or the points plate is covered in oil.

5. The tab on the bottom of the coil not making contact w/ the brass button on the cap. (With the cap on, the tab must firmly contact the brass button. No contact = no spark.) Check for continuity between the top of the coil and the tab; you should see about 6k ohms.

6. A grounding issue inside the distributor: Incorrect positioning of the spring clip on the plate causing the pigtail to ground. (the open part of the clip goes between 7 & 9 o'clock on the plate. That puts the straight part of the clip opposite of the timing screw at 3 o'clock) or the condenser wire is grounding to the plate or side of the distributor.

7. Incorrect seating of the coil on the distributor due to a loose bail or no gasket.(the coil must not move at all; if it does, replace the gasket or bail. Or stick some cardboard under the bail).

8. Water/moisture inside the cap due to gasket failure or the absence of a gasket. (the cap AND coil have gaskets)

9. Dirty/corroded/burned/incorrectly gapped or misaligned points. I use only Wells, Blue Streak or Echlin brand points (* *see below). If you are using quality points and cannot get the gap to open to .015, chances are you need to replace the bushings. If the shaft has any sideways movement AT ALL, the bushings must be replaced. (*** see below) If the tractor has been sitting unused for a few months, its highly likely that the points are glazed. Dress them with brown paper or card stock. Do NOT use a file or sandpaper. That removes the thin metallic coating on the surface and reduces point life considerably. With the points closed, you should have continuity between them; high resistance means they are glazed.

10. Burned rotor, cracked/carbon tracked cap. Brass dust in the cap is a sure sign of bushing wear.

After find the problem & re-check the point gap, do a continuity check before you put the distributor back on the tractor. Before you start, make sure your meter/light works.

With the distributor still off the tractor, follow these steps:

1. Coil off, cap off, points open. One probe on the brass screw & the other on both sides of the open points. On the side closest to the cam, you should have continuity. Not on the other side! If you do, you will also have continuity everywhere because the points are grounded.

2. Coil off, cap off, points open. One probe on the brass screw & the other anywhere on the body of the distributor. You should have no continuity! Now, rotate the tang on the distributor....as the points open & close, you have continuity (closed) and lose it when they open.

3. Put the coil on the distributor, cap off, points open. One probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!

4. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other anywhere on the body of the distributor. You should have no continuity!

At this point, I just put the distributor, coil & cap all back on the tractor as a unit. The reason I do this is because it is real easy to get the cap or coil misaligned trying to put it back together, one piece at a time. The result is something gets broken or you get a 'no spark' problem.

It's possible to put it back on wrong & break it. Look at the slot on the end of the cam shaft. Whatever angle it happens to be, turn the distributor tang to match it. Make sure you can tell the wide side from the narrow side on both the cam & distributor! (close counts). Place the distributor on the front of the engine, gently push it in place & slowly turn the distributor body until you feel the tang slip into the slot. Rotate the distributor body until the bolt holes line up. Hand tighten the two bolts until the distributor body is flush with the timing gear cover.

* Unscrew the plate hold down screw & remove the C clip to get the plate out. Remove the shaft & weights. The weights should freely move. The tracks should not be wallowed out.


** Yesterday's Tractor kit:

Premium Blue Streak points (A0NN12107ABS), rotor, condenser, and gauge Part
No: APN12000ABSR


** Distributor cam lube NAPA:

https://www.napaonline.com/en/p/ECHML1

*** There are three ways to replace the bushings in a front distributor:

1. Buy new bushings (part numbers 9N12120 front & 18-12132 rear). Press out the old ones, press in the new ones and ream to fit. CAUTION: do not try this unless you have a press & know how to use it. If you break the base, a new one costs $130. If you bend the tower which holds the front bushing, a new plate will cost you $30. Resist the temptation to buy a new plate; most are pot metal and the threads will wallow out about the third time you change the points.

2. Take the new bushings and distributor to your local machine shop.

3. Send the distributor out for bushing replacement if you do not have a local machine shop

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Bruce (VA)

07-15-2018 14:41:50




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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So, it started with the jumper wire directly from the battery to the coil, ran 15 seconds and cut off, correct? And you checked for battery voltage at the coil as soon as it cut off, correct? What was the voltage?



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beirnem

07-15-2018 12:03:34




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
Bruce, the same thing as thru the key switch except it ran for about 15 seconds then shutoff with no spark.



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Bruce (VA)

07-15-2018 04:43:28




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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My "guess" is that it would run fine with a jumper.

Yep. My point exactly.



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Royse

07-14-2018 19:29:58




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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My "guess" is that it would run fine with a jumper.

Sounds like what happens when you have a bad key switch.

Starts and runs fine until the key switch vibrates and "turns off".

Of course, a jumper wire hooked up would prove it before buying parts.



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Bruce (VA)

07-14-2018 19:21:05




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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And what happened when you ran the jumper wire directly from the battery to the coil?



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beirnem

07-14-2018 18:40:56




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
The voltage was 6.45 volts.

But something strange occurred this morning. Keep in mind that I now have 3 coils that stopped producing spark and had been changed out. I had left the original in from the night befor and this morning I had spark so I ran the tractor for appx 10 seconds. It shut off and no spark. I put the second apparently dead coil in and I had spark soi started it running for appx 10 seconds and shut off and no spark. I lastly put in the third apparently dead coil and again it ran for appx 10 seconds and shut off and no spark. Late this afternoon I repeated this all over again with the same results. This is why I'm so baffled. It has to be something simple. How can three coils be apparently dead and after a few hours all of the sudden all three have spark again. I could see that happening to one, but three? What am I missing.

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Bruce (VA)

07-14-2018 04:37:49




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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And the voltage was what?



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beirnem

07-14-2018 04:11:44




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
I did check the voltage after it stopped but I did not try running the jumper . I will try that this morning.



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beirnem

07-13-2018 19:52:01




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
Tim, great photos. I checked the wiring and everything was good. In fact, I didn't have to do anything and I'be damed, I got spark again. I'm now suspecting that all the coils I replaced were not burned up at all, and that it might be the spring contact on the coil slightly condensing after starting for some reason. I didn't have time to try to start it again, but I did have spark again.
Bruce, I put in new points and condenser last week so I'm hoping it's not that, but I do have a spare of each.

I was told today by a tractor mechanic the same thing you guys said that it is unlikely that the coil was burned up because the coil can tolerate higher than 6 volts for much longer than originally thought by me. He said the resister for the coil was more for protection of the points and condenser then for the coil and that in theory I should be able to operate the tractor without the resister but that I would eventually burn up the points.

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Bruce (VA)

07-14-2018 03:44:24




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-13-2018 19:52:01  
" I was told today by a tractor mechanic the same thing you guys said that it is unlikely that the coil was burned up because the coil can tolerate higher than 6 volts for much longer than originally thought by me. "

That is correct.

" He said the resister for the coil was more for protection of the points and condenser"


Nope. 100% wrong. The resistor is there because of the coil. If the resistor was there for the points and condenser, you would have different part numbers for 6v & 12v points and condensers. Points and condensers in these tractors operate just fine on 6 or 12 volts.

" and that it might be the spring contact on the coil slightly condensing after starting for some reason"


Nope.


Have you checked for voltage at the coil as soon as it stops running? Or tried running a jumper wire directly from the battery to the coil?
"

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beirnem

07-13-2018 19:29:55




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
First, I want to say a big thanks for all your replies! You guys rock! I have an 860 and know it well. But this 8n is my 86yo father's and he asked me to help him with and you guys have been helping me in just two days. Those of you who said it's unlikely the coil is burned out you are absolutely correct. Because I tried to test the coil again and I got spark w/o doing anything except waiting about 8 hours. I spoke with an old tractor guy this morning that maybe when the tractor starts for those few seconds the spring on the coil might retract slightly losing contact ant therefore spark. What do you think?

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HFJ

07-13-2018 09:55:57




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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contrary to what the forum software says, i'm no expert - but i concur with harold. i am in my 7th year of running a 6 volt coil with 12 volts and no added ceramic blob resistor.

last summer, i was sure i had finally burned it up, but it turned out to be either the condenser or the ignition switch. that 6 volt coil is still on my 12 volt N and working just fine.

on my own, i could simply have been the exception to the rule, but harold's fleet of 12 volt Ns with 6 volt coils would tend to indicate otherwise ;)

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Bruce (VA)

07-13-2018 08:17:34




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
About 5 years ago, my neighbor proudly told me about fixing his 8N. Seems like it wouldnt start, so he replaced the coil. Tractor started, problem solved. I asked him if I could have the old coil. He gave it to me. I put it on one of my 8Ns where it has been ever since.

I do not know why his tractor would not start. I do not know why it did start and ran fine after he put a new coil on it. Sure, I can make a lot of guesses, but we will never know for sure.

But I do know he did not have a bad coil.

Think about this the next time you are inclined to just start replacing parts w/o determining if the part is defective.

Yes, it's possible that you have purchased 2 or 3 defective coils. Just as it's possible for you to win the lottery.

Simply put, the absence of spark does not always point to defective coil, especially in 10 seconds.

Look at the points. Are they burned or pitted?

Test the condenser. Or just replace it.

Carefully check your wiring.

And as soon as it stops running, check the voltage at the coil.

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KCM

07-13-2018 07:52:29




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
I'd be replacing the points and condenser. The points probably have a burnt spot or maybe the condenser is shorting out. No way you would be going through coils that fast.



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beirnem

07-13-2018 05:42:12




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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Tim PloughNman Daley

07-13-2018 05:35:38




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
I'm just spit-ballin' here, but I'd suspect the wiring is still cobbled up. Is your battery a 6V or a 12V? Which resistor did you buy?-OEM Ballast or the 1.0 OHM in-line ceramic external one only used with a 6V coil and 12V system?

ORIGINAL BALLAST RESISTOR:

1.0 OHM CERAMIC EXTERNAL RESISTOR ADDED IN-LINE WITH FRONT-MOUNT, 6V COIL 12v SYSTEMS ONLY:

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Tim PloughNman Daley

07-13-2018 05:16:13




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
I'm just spit-ballin' here, but I'd suspect the wiring is still cobbled up. Is your battery a 6V or a 12V? Which resistor did you buy?-OEM Ballast or the 1.0 OHM in-line ceramic external one only used with a 6V coil and 12V system?

ORIGINAL BALLAST RESISTOR:

1.0 OHM CERAMIC EXTERNAL RESISTOR ADDED IN-LINE WITH FRONT-MOUNT, 6V COIL 12v SYSTEMS ONLY:

ORIGINAL FORD 8N TRACTOR WIRING DIAGRAM:



Tim Daley(MI)

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beirnem

07-13-2018 04:10:01




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
I agree that 10 seconds is rather quick for the coil to burn out, but I don't have any other explanation. I would like to test the (now 4) apparently dead coils off the tractor but I don't know how. I know hou with the side mount round coils, but the front mount square coils are so different don't have the knowledge. On a side note, yesterday I went to the ford dealership and only one of their techs knew anything about this tractor and he is on vacation.

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beirnem

07-13-2018 04:01:27




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
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Originally, the resister was by-passed by the PO. I contacted YT and they sent me a new OEM looking resister.



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HCooke

07-12-2018 14:30:52




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
" The tractor ran for about 10 seconds then shutoff and no spark."

I am skeptical that you burned out a coil in ten seconds. I would love to test your questionable coils on one of my front mount Fords. I have purchased both 6 and 12 volt tractors that had bypassed the resistor for who knows how long and they ran. I rewired them using the OEM resistor and all but one of them are still running with those coils. Those coils are not that fragile. Of course you could have bought a defective one. PS I have six 9Ns and 2 8Ns with front mount distributors.

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Bruce (VA)

07-12-2018 09:43:21




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 Re: Burning Out front mount 6 volt coils in reply to beirnem, 07-12-2018 09:22:40  
Are You using the oem ballast resistor?



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