Coil Hot - Wrong 12v sent

[gatractorelli]

Well, I couldnt figure out why when I hit the starter switch I got nothing, drove me crazy till I touched the Coil. It was burning hot, come to find out they sent me a coil without a resister built in so it was draining the power from the battery. Freaking Yesterday Tractor!!!

 

[Fixingfarmer]

at least it’s an easy fix. Stinks you have to ship it back and wait. I’ve got enough laying around that I measure the resistance of them even when they are new compared to old often even if they are nasty corroded the resistance will still be there (sometimes not but often 3 ohms or 1.5 is still measurable even if it does fix the problem) before putting them on…who knows sometimes returns can get slipped back in a box if somebody else had the same thing going on and returned the wrong one. I’d bet money they are one of the most often returned items. Qc looks at the return and sees a new coil in a new box. If the box has the wrong part number…whoopsie

Often they are labeled with an ohm rating as well

 

[used red MN]

No matter if you have a 6 or 12 volt coil if you turn on the ignition for any length of time, say 2 -3 minutes, with the engine stopped the coil will get hot. Although arguably the 6 volt coil on a 12 volt battery will heat up faster. On a good fully charged battery none of this should drop the voltage to where it won’t engage the starter. The engine will run with a 6 volt coil it will just erode the ignition points contact surfaces quicker.

 

[gatractorelli]

No matter if you have a 6 or 12 volt coil if you turn on the ignition for any length of time, say 2 -3 minutes, with the engine stopped the coil will get hot. Although arguably the 6 volt coil on a 12 volt battery will heat up faster. On a good fully charged battery none of this should drop the voltage to where it won’t engage the starter. The engine will run with a 6 volt coil it will just erode the ignition points contact surfaces quicker.

The coil was 12v, just no resister built in.

 

[Fixingfarmer]

ah so it’s not spinning over I took it as there wasn’t even a pop

 

[NDIHC]

A coil without a resistor won't keep your starter from engaging. I've been running a couple of tractors on 12 volts with no resistor or "internal resistor" coils for 20 plus years. The resistor just helps the points last longer.

 

[used red MN]

The coil was 12v, just no resister built in.

Then it is essentially a 6 volt coil with 1plus to 2 ohms of primary resistance. The resistance of the coil is changed by the diameter and length of the wire in the coils primary winding and not by adding an “internal resistor”

 

[JMOR]

got to be more to this story

 

[gatractorelli]

got to be more to this story

I have doubled check the wiring as its all new since I am rebuilding every single part of the tractor, including the engine. I will replace the start switch as well just to be sure.

I tested power to the start solenoid and got 12V, but didnt get anything on the other side of the starter solenoid going to the starter and hence no power to the starter, even with the key switched over.

 

[Jim.ME]

First off coils are internally wound to provide the correct resistance, there have not been actual resistors inside coils for many, many years.



What are you working on? The NAA you have posted about? (it helps to know, we can't see it)

What did you order? Part number?

Some coils are labeled as 12 volt External Resistor Required. Some say 12 volt No Resistor Required. Was the one you got labeled?

If you left the switch turned on, and the points were closed, while you were working on it, there will be constant current flowing through the coil which will cause heating.

As has been posted the coil isn't stopping the starter from engaging. Do you have a part number for the solenoid? Even though many solenoids look alike they are wired different internally. If this is your NAA it was 6 volts originally and the solenoid was grounded by the start button by the shift lever. What have you converted in making it 12 volts?

 

[BarnyardEngineering]

I have doubled check the wiring as its all new since I am rebuilding every single part of the tractor, including the engine. I will replace the start switch as well just to be sure.

I tested power to the start solenoid and got 12V, but didnt get anything on the other side of the starter solenoid going to the starter and hence no power to the starter, even with the key switched over.

Measuring 12V with nothing going on is only part of the story. If you have bad/high-resistance connections, they will read 12V just fine until you try to pass current through them, then it will instantly go to 0V.

Honestly, Yesterday's Tractor sent you what you ordered. There are no such thing as "internal resistor" coils. There are "no external resistor required" coils, and "external resistor required" coils. This stems from the days of yore when 12V electrical systems were a new thing. Car manufacturers would still equip the cars with "6V" coils, but use a ballast resistor (or resistance wire) to step down the voltage. Shadetree mechanics would come into the auto parts store and ask for a 12V coil for their such-and-such, and the parts man would hand them a 6V coil, because it's the same thing. The customer would go, "HEY!" and a fight would ensue. Clueless parts man knows nothing. Foul words said. Punches thrown... Well, maybe not that dramatic, but it was a source of confusion because those shadetree mechanics didn't understand the technology.

Having a "6V" coil with a ballast resistor offers one distinct advantage. It allowed car manufacturers to BYPASS the ballast resistor during start-up, so that the engine would receive a good hot spark during cranking, when the battery voltage dropped. If your starter solenoid has a port labeled "I" that is what that is for.

 

[gatractorelli]

First off coils are internally wound to provide the correct resistance, there have not been actual resistors inside coils for many, many years.



What are you working on? The NAA you have posted about? (it helps to know, we can't see it)

What did you order? Part number?

Some coils are labeled as 12 volt External Resistor Required. Some say 12 volt No Resistor Required. Was the one you got labeled?

If you left the switch turned on, and the points were closed, while you were working on it, there will be constant current flowing through the coil which will cause heating.

As has been posted the coil isn't stopping the starter from engaging. Do you have a part number for the solenoid? Even though many solenoids look alike they are wired different internally. If this is your NAA it was 6 volts originally and the solenoid was grounded by the start button by the shift lever. What have you converted in making it 12 volts?

Ford NAA
My Coil was not labeled.
I didnt leave the switch on, only turned on when tried the starter button.
105282 Distributor Coil 12 Volt
105689 Starter Solenoid Ford
Style 12 Volt 4
105687 Ignition Switch New Alls
Chlmrs 70225310
103141 Alternator Conversion
Kit, New, Ford
112209 Starter Ford Style DD
with Drive (3115

Its not a convertion as I stripped everything from the tractor but maybe its possible the starter switch is not grounded?

 

[JMOR]

#105689, I do believe is wrong for the NAA

 

[gatractorelli]

Measuring 12V with nothing going on is only part of the story. If you have bad/high-resistance connections, they will read 12V just fine until you try to pass current through them, then it will instantly go to 0V.

Honestly, Yesterday's Tractor sent you what you ordered. There are no such thing as "internal resistor" coils. There are "no external resistor required" coils, and "external resistor required" coils. This stems from the days of yore when 12V electrical systems were a new thing. Car manufacturers would still equip the cars with "6V" coils, but use a ballast resistor (or resistance wire) to step down the voltage. Shadetree mechanics would come into the auto parts store and ask for a 12V coil for their such-and-such, and the parts man would hand them a 6V coil, because it's the same thing. The customer would go, "HEY!" and a fight would ensue. Clueless parts man knows nothing. Foul words said. Punches thrown... Well, maybe not that dramatic, but it was a source of confusion because those shadetree mechanics didn't understand the technology.

Having a "6V" coil with a ballast resistor offers one distinct advantage. It allowed car manufacturers to BYPASS the ballast resistor during start-up, so that the engine would receive a good hot spark during cranking, when the battery voltage dropped. If your starter solenoid has a port labeled "I" that is what that is for.

So first, this is a hobby not a job for me. I enjoy figuring it out and seeing the results.

Second, if the part shows internal resistor for a coil then I expect that is what it means. If mechanics around the world think differently, okay sure.

Third, I actually called into the YDT and told them what I needed, so they are the ones who sent me the parts based on the fact that I am starting from scratch on all the parts.

Finally, the reason coming to the forum is to learn but also vent some frustration. With or without resistor is a mute point if the person ordering for me knows the story and has better insight into requirements.

 

[BarnyardEngineering]

Ford NAA
My Coil was not labeled.
I didnt leave the switch on, only turned on when tried the starter button.
105282 Distributor Coil 12 Volt
105689 Starter Solenoid Ford
Style 12 Volt 4
105687 Ignition Switch New Alls
Chlmrs 70225310
103141 Alternator Conversion
Kit, New, Ford
112209 Starter Ford Style DD
with Drive (3115

Its not a convertion as I stripped everything from the tractor but maybe its possible the starter switch is not grounded?

If you didn't leave the switch on, then the coil didn't run down your battery, and is not causing the tractor to not crank.

Even if you stripped the wiring from the tractor it's considered a conversion. You still need the ballast resistor unless you buy the "no external resistor required" coil. A standard 12V coil requires an external resistor.

 

[BarnyardEngineering]

#105689, I do believe is wrong for the NAA

Perhaps, but a solenoid is a solenoid in what it does and how it works, and 12V is 12V. Unless you're talking about ignition coils, LOL.

 

[gatractorelli]

If you didn't leave the switch on, then the coil didn't run down your battery, and is not causing the tractor to not crank.

Even if you stripped the wiring from the tractor it's considered a conversion. You still need the ballast resistor unless you buy the "no external resistor required" coil. A standard 12V coil requires an external resistor.

Okay, point taken on the conversion. The coil I received requires an external resistor which I plan to change out for one that doesnt require.

 

[Jim.ME]

Looks like you got a 12 volt coil that needs an external resistor

One small terminal on the coil solenoid should be live all the time and to start it needs a ground from the push button by the shift lever. How does it check out?

Edited to correct coil to solenoid as originally intended, my error.

 

[JMOR]

Perhaps, but a solenoid is a solenoid in what it does and how it works, and 12V is 12V. Unless you're talking about ignition coils, LOL.

I'm afraid NOT!

 

[used red MN]

I didnt leave the switch on

Have you tested the power at the coil to see if the power is turning off to the coil when your key/switch is off? Not sure how long you had the battery connected.