I'm getting discouraged & need some help. 1939 9N with 12V conversion & GM alternator. I was plowing snow & it quit. Checked spark @ #4 plug & it was intermittent. Installed NEW: points, rotor, condenser & gaskets in the distributor. I checked with the distributor off (with a meter) that the points were opening & closing - looked to be fine. When putting the coil wire back on the top, the terminal broke off. So, I got a NEW 12V coil. Checked spark @ #4 plug & it looked good. Tried to start it, but it only sputtered once. Checked spark @ #4 plug again & it was intermittent, then stopped. Now, no spark @ the plugs. Before all of this happened, I could smell the battery, like it was overcharging. The battery gave up. New battery & it was running good. Not sure if that has anything to do with the no spark problem or not, just thought I'd mention it. Also, changed the voltage regulator when I was changing the points, etc. Any ideas? Thanks guys.
- Thread starter 1pickup
- Start date
Bruce (VA)
Well-known Member
Wet and or cracks distributor cap will cause that. Common problem with the front mount when plowing snow and the distributor getting wet and then you loose spark. Dry cap off like Bruce says and or spray it with starting fluid and dry it. Once you dry it after spraying it look for little lines in the cap. If you see lines those are cracks and it need to be replaced
hey pick'em-up........the 12-volt alternator has built in voltage regulator. Gonna makka WAG (Wild A$$ Guess) yer talk'n 'bout the 2-terminal round can cut-off underneath the battery tray used with the 6-volt genny. In the 9N-2N scheme, YOU are the voltage regulator. There's a voltage adjust screw on the back end of the 6-volt genny that you adjust fer about +3 amps charge at 1/2-throttle on the dashboard amp-meter. You haffta gitt off'n yer butt-bucket and walk around to the genny and guess how much to turn the screw and then walk around to the amp-meter and read-itt again. The need to adjust the original genny screw depending on whether you had headlites ON or OFF. Now you have a modern alternator with built-in regulator so you don't haffta re-adjust yer 6-volt genny screw. Amazing, eh? Remember, with either the original 6-volt or modern 12-volt square can coil, BOTH need the "infamous" ballast resistor.
As fer yer sparkie problem, the 4-nipple capple is NOT waterproof and yer fan kenn blow snow thru the crackles. 2nd, condensers seldom go bad, thats NOT chur problem. Didja remember to POLISH the INVISIBLE corrosion from between the new points? Me? I'd clamp the corner of $1-bill (cheap) between the points and PULL. Ennytime you have runnin' issues, change yer sparkies. Recommend AutoLite 437's gapped 0.025. Don't throw yer FLOODED sparkies away, just clean'n'dry 'em, one-atta-time in HOT runnin' engine and save'um fer the NEXT time (and there will be a NEXT time) While ya didn't mention it, with all yer changin', DON'T USE modern string sparkie wires, use old fashioned COPPER CORE sparkie wires. .........HTH, Dell, yer self-appointed sparkie-meister
As fer yer sparkie problem, the 4-nipple capple is NOT waterproof and yer fan kenn blow snow thru the crackles. 2nd, condensers seldom go bad, thats NOT chur problem. Didja remember to POLISH the INVISIBLE corrosion from between the new points? Me? I'd clamp the corner of $1-bill (cheap) between the points and PULL. Ennytime you have runnin' issues, change yer sparkies. Recommend AutoLite 437's gapped 0.025. Don't throw yer FLOODED sparkies away, just clean'n'dry 'em, one-atta-time in HOT runnin' engine and save'um fer the NEXT time (and there will be a NEXT time) While ya didn't mention it, with all yer changin', DON'T USE modern string sparkie wires, use old fashioned COPPER CORE sparkie wires. .........HTH, Dell, yer self-appointed sparkie-meister
The fact that you have an alternator doesn't mean you don't have a voltage regulator. I've bought 3 in the last year with alternator and voltage regulator. One was even kept Ford by using the Motorcraft alt and a solid state regulator. that is a seperate system from the ignition though. If you had a 6 volt coil before and had the voltage reducing resistor, you don't need that with a 12 volt coil. You will still need the factory type though. also make sure the littke pigtail on the bottom of the coil is making contact with the brass screw on the points, and the little tab is making contact with the little button on the cap.
Looks to be an older GM alternator that uses an external regulator. It was(& still is) using a Ford regulator. The 12V conversion was done before I got the tractor. Seemed to be working fine, until I could smell the battery cooking. I only mentioned that, because I thought it was possible that overcharging may have damaged something. Since it won't currently start, I can't tell you if the regulator cured the problem or not. I did remove the distributor & replace points, rotor, condenser, cap, gaskets & a new coil. It looked to have good spark at first, but after only sputtering once, I checked the spark again & it was intermittent, & then gone. I "plow" with a back blade, so moisture probably not a factor. With everything replaced in the distributor, moisture is definitely not the problem. Can you think of what else might make my spark go from good, to intermittent, to non-existant? I'm kind of at a loss for where to look next. I'm new to tractors, but I have rebuilt the hydraulic pump & it works good. I've been around cars for 40+ years. Just need to be pointed in the right direction. The regulator is mounted under the battery & there appears to be a round resistor mounted next to it.
Cheap points with a plastic rubbing block might do that.
So could the plugs or plug wires
How are you checking for spark?
If you're using a plug held to ground, good old school technique,
the plug itself may be bad or not be making good ground.
An adjustable air gap spark tester is a better choice.
So could the plugs or plug wires
How are you checking for spark?
If you're using a plug held to ground, good old school technique,
the plug itself may be bad or not be making good ground.
An adjustable air gap spark tester is a better choice.
tractorguy2
Well-known Member
A bad key switch will give you intermittent spark.
It doesn't have the stock ignition switch/starter button. It's an aftermarket auto type, with start function built in. Too cold to work on it today, but I'm going to need it if it snows again soon. I'll take the distributor back off & clean the new points (didn't do that when installed), check connections (again), & see if that helps. Other than grounding a plug to the engine, Is there a better way to troubleshoot where the problem is coming from? thanks
Bruce (VA)
Well-known Member
" It's an aftermarket auto type, with start function built in. "
Check out tip # 28. That's an accident waiting to happen.
" Is there a better way to troubleshoot where the problem is coming from?"
Yes.
Assuming that the bushings & advance weights are ok (*see below), & that you have correct voltage to the coil (battery voltage with the points open and about half that with the points closed), the most common electrical failure (no spark, weak spark) points on the front mount are:
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
3. The copper strip is broken or grounded to the plate. (look very carefully for cracks & breaks).
4. The condenser wire grounding to the plate or side of the distributor.
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.)
6. 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)
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.
10. Burned rotor, cracked/carbon tracked cap.
Make sure to check bushing wear. If the shaft has any sideways movement AT ALL, the bushings must be replaced.
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.
* *NAPA part numbers:
? Points: FD-6769X
? Condenser: FD-71
? Rotor: FD-104
? Cap: FD-126
75 Tips
Check out tip # 28. That's an accident waiting to happen.
" Is there a better way to troubleshoot where the problem is coming from?"
Yes.
Assuming that the bushings & advance weights are ok (*see below), & that you have correct voltage to the coil (battery voltage with the points open and about half that with the points closed), the most common electrical failure (no spark, weak spark) points on the front mount are:
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
3. The copper strip is broken or grounded to the plate. (look very carefully for cracks & breaks).
4. The condenser wire grounding to the plate or side of the distributor.
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.)
6. 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)
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.
10. Burned rotor, cracked/carbon tracked cap.
Make sure to check bushing wear. If the shaft has any sideways movement AT ALL, the bushings must be replaced.
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.
* *NAPA part numbers:
? Points: FD-6769X
? Condenser: FD-71
? Rotor: FD-104
? Cap: FD-126
75 Tips
Bruce, you are obviously the man. I printed out your response & followed it with the exception of pulling the plate out to inspect weights, etc. The only things I found suspect, were the spring clip was clocked wrong (looked like it may have been the culprit), & the condenser tab was a little close to grounding out. So, I removed & re-installed the spring clip as stated, & bent the terminal on the condenser wire to be sure it wasn't grounding. Tested as you suggested & everything worked great. Re-installed the distributor (as a unit, checked spark @ #4 plug - looked good. Sprayed a little starting fluid & it fired right up. I had to shut it down to reconnect the throttle I forgot to put back together. And then it happened again. No start. Checked #4 plug for spark. It fired 4 times, then nothing. Checked #3 plug - nothing. What the hell am I missing? How can it go from good spark, to intermittent, to nothing? The only other thing I can see that isn't 100%, is that my new coil (purchased off of this website) doesn't seem to be as tight as it should be to the distributor. Yes, it has new gaskets. I don't think that's it, but I'm at a loss otherwise. Any more suggestions? Thanks in advance - 1pickup
Bruce (VA)
Well-known Member
" Any more suggestions?"
Yes
" How can it go from good spark, to intermittent, to nothing? "
Very easily; you at least have 3 possibilities:
" my new coil (purchased off of this website) doesn't seem to be as tight as it should be to the distributor." That's one. Put some cardboard under the bail.
Make sure to check bushing wear. If the shaft has any sideways movement AT ALL, the bushings must be replaced. That's two.
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. That's three, and the most likely. You can not usually SEE a bad insulator. Trust your meter.
75 Tips
Yes
" How can it go from good spark, to intermittent, to nothing? "
Very easily; you at least have 3 possibilities:
" my new coil (purchased off of this website) doesn't seem to be as tight as it should be to the distributor." That's one. Put some cardboard under the bail.
Make sure to check bushing wear. If the shaft has any sideways movement AT ALL, the bushings must be replaced. That's two.
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. That's three, and the most likely. You can not usually SEE a bad insulator. Trust your meter.
75 Tips
The insulator looked good & I tested it as much as I thought possible. If it was bad, I assume that the continuity testing of the points opening & closing would be erratic. I thought everything seemed to be working as it should. I'll try the cardboard/tighten up the bail clip trick. If that doesn't cure it, I will have to remove the distributor again & check the bushings. The plug wires are pretty old & don't seem to clip into the new cap as well as they did to the old one. I will order new plug wires as well. Thanks for being patient with my questions. It's frustrating when it works sometimes, but not others. Makes tracking the problem much harder.
Bruce (VA)
Well-known Member
Yea, an intermittent short is a PITA.
pulled the coil & used the old gasket, as it seemed to make it fit better, but maybe that's my imagination. did the cardboard trick. checked spark & it was looking good. started the tractor & it ran as it should for about 7 seconds. then, it died. no spark. looks like it's time to tear the distributor back off & check the bushings. Thanks again for the help Bruce. - 1pickup (Dave)
Bruce (VA)
Well-known Member
While you do need to check the bushings & replace them if needed, bad bushing will not result in no spark. Intermittent or weak, but not a total loss of spark.
Are you checking voltage to the coil when you get no spark?
Seven seconds? You can check the bushings, they're a wear part.
Personally I don't think a 7 second run time would be bushings.
I would double check that connection Bruce mentioned.
The insulator repair is a simple task.
This one didn't even have the concave screw but worked.
Have you tried hot wiring it to eliminate the key switch?
Personally I don't think a 7 second run time would be bushings.
I would double check that connection Bruce mentioned.
The insulator repair is a simple task.
This one didn't even have the concave screw but worked.
Have you tried hot wiring it to eliminate the key switch?
Pulled it all back apart. Bushings are not great. I ordered those & will replace when they show up. Can't really check anything else until my parts show up & I can put it back together. Everything else looked to be fine to me. Weights seemed to be moving fine. Before I took the distributor off the engine, I took the cap off & tried to wiggle the rotor to see what kind of play there was, & it didn't seem too bad. I could turn it some back & forth - guessing that's the weighted advance mechanism working. After I took it completely apart, I could see plenty of play in each bushing by inserting the center piece (whatever it's called), backwards into each of the bushings. That way, it was only making contact with one bushing at a time. Is it possible to have the slot in the camshaft, or the tang on the distributor worn enough to cause this? I assume that for 1939 technology, the timing isn't quite that precise. I really can't tell that there is a bigger side to the tang on the back. Just been pointing the rotor back where it was when I took it apart. As for the voltage checking, please be specific as to where you are checking the voltage, so I can try that after I get it back together with the new bushings. Thanks guys!
Bruce (VA)
Well-known Member
" As for the voltage checking, please be specific as to where you are checking the voltage,"
At the top of the coil.
W/ the distributor on the tractor, key on, put one lead on the post & the other on the chassis of the tractor. Points open, battery voltage. Points closed, about half that.
" I really can't tell that there is a bigger side to the tang on the back. "
It is. Measure it & mark the wide side.
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.
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.
" Is it possible to have the slot in the camshaft, or the tang on the distributor worn enough to cause this? "
Theoretically, yes. Practically, no. That's what the bushings are for. Check the wear parts with a micrometer and compare what you have to the factory specs (below).
Factory Specs:
Shaft top .4367 / .4370
Shaft Bottom .8625 / .8630
Cam Flats .789 / .791
Cam Lobes .869 / .871
Base Tang .177 / .178
75 Tips
At the top of the coil.
W/ the distributor on the tractor, key on, put one lead on the post & the other on the chassis of the tractor. Points open, battery voltage. Points closed, about half that.
" I really can't tell that there is a bigger side to the tang on the back. "
It is. Measure it & mark the wide side.
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.
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.
" Is it possible to have the slot in the camshaft, or the tang on the distributor worn enough to cause this? "
Theoretically, yes. Practically, no. That's what the bushings are for. Check the wear parts with a micrometer and compare what you have to the factory specs (below).
Factory Specs:
Shaft top .4367 / .4370
Shaft Bottom .8625 / .8630
Cam Flats .789 / .791
Cam Lobes .869 / .871
Base Tang .177 / .178
75 Tips
Big snow is supposed to be coming tomorrow, so I put together what I have. Which means, only a new front bushing in the distributor, as the rear one hasn't shown up yet. So now the distributor has new: front bushing, points (gapped @ .015), condenser, gaskets, 12V coil, bail clip, rotor, & cap. Added a new set of plug wires & a new ignition switch. Started harder than it should have, but it fired up & ran as it usually does. So. I backed it out of the shop & it quit - NO SPARK. Ran 1 minute, at most. Went to check spark @ the plugs & it started & ran on 3 cylinders for a couple seconds, lost spark again & quit. Now, has no spark again. Checked voltage at the coil & it showed 12V. I suppose that points to something in the distributor, but I've had it apart several times & don't know what I'm missing.
Ok, back at this after a long hiatus. I pulled the distributor (AGAIN!) checked it with a meter against Bruce's list. Cap off, points open, etc... All checked great. Put it back together & it fired up easily. I backed it out of the shop & let it run for a few minutes. Went to the house for a minute & it quit while I was gone. Maybe ran 5 minutes. Checked the following: 12V at coil = OK. Spark at plug = nope. Seems that when it gets to operating temp, something is opening & stopping the spark. Remember it has: new coil, cap, rotor, condenser, points. Generally if it's a coil, doesn't it keep running until it's shut off? Had that problem with a mower. Ideas?
Bruce (VA)
Well-known Member
It UT could be the coil, but 5 minutes of run time and no spark tells me it's the condenser.
Pull the distributor, replace the condenser, check the points, do the continuity tests and see what happens. Post back with results.
I let it sit and cool down. It started easily. After it ran 20 minutes, I shut it off and restarted it 3 times. Let it run another 20 minutes. Restarted it a few times. Let it sit for an hour or so, and it started easily again. So, it is working for now. When things fix themselves, I get nervous. Pretty sure it will lose spark when I am turning around in the middle of the road, or when a snow storm is coming. Since it's working, I hesitate to take it back apart. So, unless there is an answer to this intermittent spark problem that someone else has come across, I'll probably leave it alone. WHEN it dies again, I'll try the new condenser & go through the check list. Bruce, you are ther man when it comes to these things.
Similar threads
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.
Copyright © 1997-2024 Yesterday's Tractor Co.
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy