8n melted coil

Jay007

New User
New to the group, recent Ford 8n owner.

A bit of a back story. I bought a 1951 Ford 8n just over a week ago with the intent of using it for snow removal, my driveway is 750ft long.

I wanted to do some basic maintenance/tune up to make sure its ready for the job as its forecast to get down to -37C (-35F) by this time next week.

After reading many posts on here I picked up a set of AL437 plugs and ordered a new condenser, points, rotor and distributor cap.

Last night I changed the plugs and wanted to take a look at the screen on the fuel line at the carburetor, so with the tractor running I shut off the gas and waited for the tractor to quit. Around this time I received a phone call and had to go into the house. About an hour later I realized that I had left the key on. Went back to the garage that was now full of smoke and a severely melted coil was half on the floor and splattered on the tractor.

The tractor has been converted to 12v, not sure if it was done with a kit or home done. The resistor under the ammeter is wired in.

I will go today to get a new coil, from reading on here I was considering the NAPA ICI4SB, which info says no resistor is required? Is this my best option?

I also read somewhere that my ignition switch is most likely cooked. How can I check this?



Once I get a new coil I want to do a fairly intensive re-wire and am likely going to have multiple more questions as electrical is not my strong point.

Is there is a wiring diagram that you guys that know what you re doing approve for my situation?

If there s any more info needed to answer please let me know, I hope to have this thing back up and running in the next few days.

Thanks in advance.
Jay
 
Yep, see tip # 38.

It happens twice as fast on 12 volts!

Get out your meter and check the switch; chances are it's fine.

If you melted the coil, the points are likely melted as well. Hopefully, you have a good set to replace them with ( see tips 66, 67 & 68) or you will get to replace them again soon.

The NAPA 12v coil, IC14SB is fine and no resistor required.

Re the wiring diagram, Google " wiring diagrams JMOR " and find the one that fits your tractor.

And also check out tip # 39. You have a 70 year old tractor; unless you are as old as the tractor, chances are a lot of the stuff on it will be very new to you!

Check back w/ more questions.
75 Tips
 
Thanks Bruce,

through some further reading of your 75 tips, I think i will get the napa 12v coil, and as per tip #30 (You always need the OEM ballast resistor with a front coil even if you use a 12 volt coil) I will wire that in and forget about an additional external resistor.

Just hours before this happened I ordered new points, condenser, rotor and cap. I will be ordering a manual and FO-4 shop manual ASAP as well as new plug wires when I can source copper cored.

I will also be pickling up a napa 1010 oil filter and some 10w-30 oil, with the climate up here in Canada I figure its best to change oils for summer and winter as I do in my other vehicles. I will likely go with 30w in the summer. With -35f next week 30w might be a bit thick. The wiring on this tractor is a bit of a maze right now so hopefully I can sort out the wiring diagrams.
 
" You always need the OEM ballast resistor with a front coil even if you use a 12 volt coil)"

No!!!!!

You do NOT have a front distributor tractor!

You have a side distributor on a 1951. NO resistor of any kind on a 12v side coil.
75 Tips
 
Just check for good continuity (or lack of resistance) on the switch with your tester/multimeter when ON, and no continuity when OFF. Most of those
switches are pretty flimsy in terms of long term durability, but as Bruce noted, I?d be surprised if the switch fried. They can handle that kind of
amperage. If you don?t have a multimeter, go buy one. They?re cheap, and you?ll need it to check the rewire.

I?d totally recommend the rewire with a known good *new* wiring harness, solved a lot of intermittent issues with my tractor, as my unit?s previous
owner wasn?t great with electrical (thankfully, electrical is something I do know quite a bit about, unlike a lot of the mechanical side).
 
Apparently I was reading too fast. Thank you

Just scouring wire diagrams now to find the best one for this application.
 
I have the ammeter.

I believe I have found the one you're referring to, the one difference I have is my solenoid, only has 2 posts, no top post. Apologies if it sounds like I don't know what I'm talking about....its because I don't haha
 
That's not a top post.

The solenoid has 3 posts; 2 large, one small. The smaller post, on the back toward the block, is wired to the neutral safety switch as shown in JMOR's diagram.
75 Tips
 
" I?d totally recommend the rewire with a known good *new* wiring harness, solved a lot of intermittent issues with my tractor,"

Yep.

Tip # 42.

Two of my 4 8N's came here w/ OEM wiring, mostly frayed often bare.

The other 2 came here w/just a huge mess of wire nuts, solid wire, etc, etc.

It's just so much easier to pull all that crap out and do it right.
75 Tips
 
(quoted from post at 15:40:59 01/07/20) " I?d totally recommend the rewire with a known good *new* wiring harness, solved a lot of intermittent issues with my tractor,"

Yep.

Tip # 42.

Two of my 4 8N's came here w/ OEM wiring, mostly frayed often bare.

The other 2 came here w/just a huge mess of wire nuts, solid wire, etc, etc.

It's just so much easier to pull all that crap out and do it right.
75 Tips
ouple of lines here sure sounds like it is NOT a 1951 (2 posts, & melted coil with half on the floor, resistor on dash)??? What does he really have?
 
The Alternator is on the Left side, opposite the distributor and carburetor.


cvphoto1599.jpg

Heres the coil, the part on the floor blew out the top.


cvphoto1600.jpg

This is the resistor under the ammeter I'm referring to


cvphoto1601.png

Here's the solenoid, as said there is probably a post on the back, in the week i've had the tractor I havnt checked.


cvphoto1604.jpg

Just an overall pic of the tractor.

Also, I am not 100% certain its a '51 as there is no stamped serial number on the block. There is the flat spot where the number is normally stamped
but it has no stamping. I am going off some casting numbers found on the left side rearwards of the block and below the battery.
 

sure looks like a side mount to me, but it also has the front mount OEM resistor. maybe a newer engine swapped into an early 8N?
 
(quoted from post at 19:40:14 01/07/20)
sure looks like a side mount to me, but it also has the front mount OEM resistor. maybe a newer engine swapped into an early 8N?
K, side mount distributor. Note that the resistor is not connected as a resistor, but simply being used as a terminal block. So, IC14 (no res reqd) should be just fine.
 
To check ignition switch use a multi meter. Resistance, Ohm, Continuity readings are not sensitive enough for this test, unless the switch is totally fried, us the DC volt setting. Tractor off, Battery connected and switch open/off touch one probe to terminal on the battery side and the other probe to ground. This voltage should be the same as battery voltage. Next touch one probe to terminal on the coil side of switch and the other probe to ground. This second reading should be 0v. If it is not the switch has failed in the close/partially closed position. Second test is to turn the ignition switch to closed/on position and start the tractor, kind of hard with a melted coil, and again use your volt meter but this time place one probe on each terminal of the switch. You are now measuring voltage drop across the switch and this reading must be less than 0.2v, if not, switch has failed in open/partial open position. Also using the Voltmeter you can ignore the negative or positive sign.
 
Jay - I see so much wrong with your post so I'll start by saying your wiring is all mucked up no doubt. Don't go by the s/n and the model year. The important thing electrically is whether it is a front mount or side mount and if 6V or 12V. Who did your wiring job, Stevie Wonder? ; > ) First, there is no connection on the starter solenoid front terminal. I see a generator on the RH side so that would be correct and indicate a front mount. I also see an alternator on the LH side. WHY? You can't have both. I also see the ballast resistor but it is NOT wired correctly. There is no coil wire on the LH terminal post and there should be. The AUTO-LITE 437 plugs are fine but hold off on changing them or the new distributor parts. Verify if have a front or side mount -looks like front to me. If so, and using 12V best to get a square 12V coil. If you have a 6V square can and 12V you will need to get external 1-OHM resistor. You need to get the essential manuals first and get the wiring all corrected. Disconnect the battery. Verify if it is 6V or 12V and have it tested by a reliable shop. Do not reconnect power yet. Lights? Disconnect those as well. A new harness is required. Get a good one, not the cheap vinyl $20 ones. Round can coils are more robust than the square ones so can usually survive an accidental key left on BUT not if the wiring is all mucked up. Something is horribly wired incorrectly. If you choose to go with 12V you will remove the RH generator and install the alternator in place. You will also remove the Voltage Regulator regardless if front or side mount. Start with the basic OEM 6V/POS GRN Wiring Diagrams. I'd pull distributor and bench test it, rebuild it if needed. Once wiring is all correct, connect battery but don't turn over. Perform continuity test for coil and dist. Then can do a spark test. If all pass, then can start.

FORD 8N TRACTOR WIRING DIAGRAMS:
MXLPPwsh.jpg
CfuUUP3h.jpg
rxNF128h.jpg
lz8RwfQh.jpg

FORD N-TRACTOR 6V/POS GRN WIRING PICTOGRAM WITH FRONT MOUNT DISTRIBUTOR:
TBC19a5h.jpg

FORD N-TRACTOR 12V/NEG GRN WIRING PICTOGRAM WITH SIDE MOUNT DISTRIBUTOR:
2KkQjBah.jpg
3XguzBIh.jpg

*PICTOGRAMS courtesy of JMOR


FORD 8N TRACTOR ESSNETIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS:
qI9P22kh.jpg


Tim Daley(MI)
 
It is pretty common in the power industry to see AC transformers fail like this. Usually comes with a spectacular fire too. This kind of failure that "ruptures the tub/can" in my world is do to an internal fault. The coil is a transformer after all......
 
(quoted from post at 10:53:04 01/09/20) It is pretty common in the power industry to see AC transformers fail like this. Usually comes with a spectacular fire too. This kind of failure that "ruptures the tub/can" in my world is do to an internal fault. The coil is a transformer after all......
alling the ignition coil a 'transformer' is an over-simplification.....but you have the right to call it a "can of dog poop" if you like. Fact is that it has a DC input while points are closed (you can't 'transform' DC) and all action after the points open occurs with NO power input to the ignition coil. The energy output derives from the energy stored in the large inductance of the coil's magnetic core during the time the points were closed, supplying DC current.
 
Thanks for all the comments.

It is definitely a side mount distributor.

There is no generator, it has been replaced with 12v alternator.

The ballast resistor is not wired in, I believe he was using it as a junction point as he used one top and one bottom connection, not actually running anything through the resistor.

It was a round can coil, which I have replaced with NAPA's ICI4sb that does not require an external resistor.

I have ripped the rats nest of wiring out and am currently rewiring completely going off this diagram (without resistor)


cvphoto1779.jpg


I still have a couple questions but need to get some time to get better pics to post for clarity (at work now)

He had wired in a new ignition button which added to the wiring nest, but my test show the original should be in working condition and I'm wiring it back in.

He wired the lights in a messy way and that is being re-done.

I have replaced the points, condenser, rotor, cap and coil.

Honestly I'm not sure how the old Tractor started and ran but it did.

Just a pic of what I've been ripping out.


cvphoto1780.jpg


cvphoto1781.jpg
 
With his alternate start push button, he may have been feeding power to solenoid instead of ground (as does your neutral safety start switch), so you may need to replace solenoid with a ground activated unit. Probably worth verifying before you pull hair later.
 
(quoted from post at 15:49:54 01/09/20) How would I verify this now?
erhaps you can determine if that other start switch had a ground or power wire on its other terminal (not solenoid terminal).
or some trials:
If it clicks when you do this, it is likely correct solenoid. (Try both large terminals)
If you sub the mounting bracket for large terminal and it clicks, then it is power activated & wrong one for neutral safety switch.
Polarity does NOT matter.
P.S. use conductive wrench. :)
p2M9IiI.jpg
 
A transformer can only transform voltage to higher or lower voltage if there is a changing magnetic field. Changing magnetic field in AC power is caused by the Alternating Current. The magnetic field is changing at a rate of 60Hz so transformers always work with AC.
It is true that you cannot transform DC current but the coil on an engine is a transformer. It transforms low voltage to high voltage. But you need a changing magnetic field to transform the voltage. This is where the points come in. The points opening causes the magnetic field on the primary coil to change, collapse, causing the secondary coil also to see a change in magnetic field, creating voltage and current. The output voltage is dependent on starting voltage and the ratio of windings in the coil. For example: If you start on the primary side with 6 volts and one coil, and 1000 coils on the secondary side the secondary voltage will be 6000 volts. Keep in mind power transfer has to be equal on both sides of the coil. Power is "current X voltage" so the higher voltage side will have lower current and the low side will have higher current.
 
" For example: If you start on the primary side with 6 volts and one coil, and 1000 coils on the secondary side the secondary voltage will be 6000 volts." That would be true IF the coil were only a simple transformer, which it is NOT. Start with 6v, store energy in the large inductance, open the circuit, the law of physics says the inductive current will try to continue to flow, increasing its voltage to whatever voltage is necessary to sustain that opening current, which generally reaches about 200v in primary and 20,000v in secondary. Yes, there is a turns ratio between the pri/sec in the ignition coil, but a simple transformer, that does not make. The large inductance for storing the DC energy is the difference. Reason they are "ignition coils" and not "transformers".
 
I think we are saying the same thing. I try and stay away from inductance, capacitance, EMF and CEMF when writing procedures and training plant operators. You are 100% correct in your observations that all those things happen but they are also all explainable using transformer theory.
You probably would not like my explanation for polarizing a generator or how the old voltage regulators work. Bottom line is we just want to trouble shoot the old 8N, keep her running and have fun doing it!
 
"I try and stay away from inductance, capacitance, EMF and CEMF when writing procedures and training plant operators."[b:4035c6c130] That is probably wise, as how things really work is beyond the comprehension of most laymen, so only tell them what they need to do their job in as simple of terms as possible, even when not the 'whole truth'.[/b:4035c6c130] You are 100% correct in your observations that all those things happen but they are also all explainable using transformer theory.[b:4035c6c130]Not true,as if it were that simple, as in your 6v chopped by points into AC & transformed to 6,000volts (also presumably AC), would require a 1000:1 turns ratio and the output would be pulsating AC at same frequency as points open/close. That is [u:4035c6c130]not[/u:4035c6c130] the case. Almost all automotive coils are 100:1 and produce ~20,000volts as a single pulse/arc of short duration. 20,000v in sec requires 200v in primary at turns ratio of 100:1 and that is just what one can observe with instruments. How does the 6 get to 200?, you ask? Just as I have explained, ....energy stored in a large inductance & released upon point opening.[/b:4035c6c130]
 
mvphoto47603.png

If you are ever in southern Minnesota look me up. I can provide beverage of choice, start a fire and we could talk about stuff like this. This is a serious offer.
 
Ok, so I think I'm getting close to getting this re-wire finished but have a couple questions.

JMOR's diagram wiring diagram that I'm following has the 1 wire alternator, from the mess I started wiring from it
was wired like this....The 2 prong side connection was changed to one run to the terminal on the end of the
alternator and the other runs to the ammeter. I just want to clarify as the pic in the wiring diagram shows nothing
in the 2 prong side connection and one run from the terminal to the ammeter.

cvphoto1866.jpg


cvphoto1867.jpg


Second question is, My solenoid is actually a 4 post, It worked before, but if with the re-wire and wiring in the
original start button, if it doesn't work now whats the chances this one that I dug up in the shop will work?


cvphoto1868.jpg


Help would be appreciated.
Jay
 
OK - I see now you do have the angle mount distributor. I was answering the other post from Gary at the same time and got cornfused. I'd invest in new harness though.

Tim Daley(MI)
 
(quoted from post at 23:06:30 01/09/20)
mvphoto47603.png

If you are ever in southern Minnesota look me up. I can provide beverage of choice, start a fire and we could talk about stuff like this. This is a serious offer.
OOOOwwweeee! Wow! I'm impressed!
[b:f50efe51a8]Quora is an American question-and-answer website where questions are asked, answered, and edited by Internet users, [/b:f50efe51a8]
Try some physics & engineering text books.
 
There are more than one type of 3-wire and more than one type of 4-wire solenoids. You can't differentiate by looks. The word "grounded" on the package likely means that it is not the correct unit for your application.
That alternator in photo is definitely wired wrong. If it is a 3-wire alternator, the two spade terminals are used, as is rear stud, but if it is a 1-wire alternator only the stud connection on rear is used.
Unless you have documents/markings, you can't tell a 1-wire from a 3-wire visually. Could be disassembled & probably tell by numbers on internal regulator. I would recommend that you take the easy route & try it as a 1-wire & if no charge, then add the two other wires. Or just wire it up as a 3-wire & even if it is a 3-wire, there is a good chance that it will function just fine.

Ojqhyr0.jpg
 
Thanks for the advise, I will try tonight.

Is there a difference between looping or running the wires to the ammeter terminals?
 
Your photo shows a loop style ammeter (no terminals), so if you use that meter, you have no choice but to thread the loop. Do not cut he loop & if you thread the wire thru loop in wrong direction, ammeter will read backwards. Pay attention to direction of wire in my drawing.
 
" Is there a difference between looping or running the wires to the ammeter terminals? "

Yes.

It depends on the ammeter.

Early ones has a loop, later replacements have terminals.
75 Tips
 
OK, it appeared to me that it had both, I wired to the terminals after wire wheeling them to a shine. Are they not terminals? Did I just run wire to mount studs? (original wiring in photo, not my new wiring)

cvphoto1882.jpg
 
(quoted from post at 13:38:04 01/10/20) OK, it appeared to me that it had both, I wired to the terminals after wire wheeling them to a shine. Are they not terminals? Did I just run wire to mount studs? (original wiring in photo, not my new wiring)

<img src="https://www.yesterdaystractors.com/cvphotos/cvphoto1882.jpg">

If you wire to those mounting studs you will be melting some more things.

TOH
 
(quoted from post at 14:00:13 01/10/20)
(quoted from post at 13:38:04 01/10/20) OK, it appeared to me that it had both, I wired to the terminals after wire wheeling them to a shine. Are they not terminals? Did I just run wire to mount studs? (original wiring in photo, not my new wiring)

<img src="https://www.yesterdaystractors.com/cvphotos/cvphoto1882.jpg">

If you wire to those mounting studs you will be melting some more things.

TOH
OH would not mislead you. Just mounting studs.
 
Chances are that ammeter is dead. Ran a magnet across the face of it. If the needle moves, the meter is ok. If it does not move, go buy a new one. Which will have studs for the wires .
75 Tips
 
ok so i have the tractor completely rewired as per the diagram below.

Last night I put the battery in, AND nothing.... Not even a click. The lights work! and when I turn them on the
ammeter reads.

my first thought is wrong solenoid as JMOR said. Any other thoughts?

I was going to run to town to find a replacement solenoid but not sure what to look for? "3-wire ground activated
solenoid"?

I've been calling around to try and find one and have not been successful. Does a stock 8n solinoid work? there is
a tractor wreckers not to far from here and I think they have a couple 8n's.




cvphoto1949.jpg
 
Ford 8N-11450
Standard Ign Parts SS-559
NAPA St-540
All these are 6v but work fine on 12v (still fine after 35 years)
 
I have a running tractor!!!

Big thanks to everyone!!

I still have to check a few things (charging etc) AND have to go pick up a diode as the key doesn't shut off the
tractor but it is ALIVE!!
 
(quoted from post at 18:52:48 01/11/20) I have a running tractor!!!

Big thanks to everyone!!

I still have to check a few things (charging etc) AND have to go pick up a diode as the key doesn't shut off the
tractor but it is ALIVE!!
ood for ya! what solenoid did you end up with?
 
Took about 3 hours of driving but found a NAPA St-540 in stock today.

Just finished about 3 hours of snow plowing!
 
(quoted from post at 00:36:19 01/12/20) Took about 3 hours of driving but found a NAPA St-540 in stock today.

Just finished about 3 hours of snow plowing!
appy for you my man.
 

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