Ford 8N - Electrical problem. No juice and ammeter buried into negative side.

[tmac196]

This tractor is a 6V system. 1951. New armature in generator and new battery (before the gennie was found to be at fault) and a new voltage regulator 8 weeks ago. Today I received the dreaded text while at work from my spouse, "The 8N is dead, again". This is the second most valuable piece of hardware on our spread as it pulls the manure spreader.



Upon my return home, I find the ammeter needle buried to the left (negative side) which is most unusual (It's always been zeroed) and no needle movement when the ignition switch is keyed on (also unusual-it typically deflects to the negative side a tad).



The is no juice to the electrical system and , indeed, the tractor is "dead" as my wife suggested. I have no hygrometer to test the new battery and an inspection of the wires and harness reveals no obvious causes. I put the charger on the battery, but the charger gauge needle reads that it is not receiving much charge.



I do not have a voltmeter. Any ideas as to the cause of my problem and the next steps I need to take to correct it will be most welcome.

tmac

 

[murphy1244]

something is draining your battery.

 

[MIKE R]

Check that your regulator is not screw up and tryin to run the geny like the DC motor it is. If it hot without being used theres your problem. Battery back feeding to geny. Cut out points in the regulator fused together.

 

[94BULLITT]

I agree with Mike it could be the regulator.

 

[CobyRupert]

I have nothing to offer, but am wondering: Are these positive ground 6V systems?

 

[94BULLITT]

I have nothing to offer, but am wondering: Are these positive ground 6V systems?

Yes:tractor:

 

[tmac196]

Hmmm...I just went out and put the charger back on the battery and stood there and watched. The charger needle pegs up at the 0% charge range as soon as I connect it to the battery and hums loudly (as if charging hard) for a minute or two. Shortly after this the charger gives off a loud click and the needle drops off into the 100% fully charged range. After a few seconds of this the cycle repeats itself as if there is a short and the internal mechanism of the charger is cycling to prevent it from overheating. The charger and the battery alligator clips do become warm during this process.

I will obtain a new voltage regulator and temporarily disconnect and charge the battery and report back.

Why would a new voltage regulator suddenly fuse it's points? Because it is junk?

tmac

 

[tmac196]

Update:

I disconnected the battery cables and it was drained of all charge. I put it on the charger and disconnected and removed the voltage regulator. The voltage regulator, when shaken, makes a noise as if a tiny piece is loose within the steel housing. I was able to easily start the tractor once the battery was sufficiently charged. The ammeter remained buried to the left during this process.

Next, I installed a new voltage regulator (Borg-Warner) whose housing is too big too fit on the firewall so it must be returned. The engine fired up again and I ran it for 15-20 seconds watching the ammeter remain buried in the negative the whole time. When I attempted to remove the voltage regulator after this brief use, I scalded my fingers on the hot ARM and FLD terminals much to my surprise. The BAT terminal was not particularly affected. I admit that in my haste I forgot to polarize the regulator, but should that matter and should it cause the regulator to heat up so quickly and significantly?

Have I installed the wrong wires on the wrong terminals and burned up my old voltage regulator in the process? If the VR gets this hot with simple use, wouldn't it have taken less than seven weeks to fail? Should a VR ever be so hot?

I will take the old possibly broken VR back to the place where I purchased it tomorrow and have it tested. More to come.

Any and all discussion would be welcome.

tmac

 

[Soundguy]

wow.. wish i had seen this post sooner before everyone started buying parts and burning things up without doing ANY testing.

1, with battery disconnected.. if ammeter stays pegged. it needs repalcing. if nothing else.. it's useless. it also COULD be/have been the souce of the problem. IE.. a short to ground AT the ammeter.

2, if the battery will charge up, you can remove the wires from the genny and the vreg and should be able to start her by taking a wire from the batter and putting it to the side of the key switch not connected to a resistor or running to the dizzy. disconnect that wire that normally runs tot he key to isolate the rest of the system.

that should make her start and run.

next.

get a new ammeter if your old one is pegged with battery out.

once you get the new ammeter installed. we can troubleshoot the genny and vreg. even if you don't have a vom or volt meter. we can do it using the ammeter and a test lamp. which you could make if needed.

you can actually make a genny charge without a vreg, running a full field test.

same deal.. you can motor a genny to test it.


PS.. you do not polarize vregs. you polarize generators.

you only have to pol' them if you change polarity..or change out the field pieces. or drop them alot. or have not run her in a long, long, long time.

if you accidentally ground the field on a 8n genny.. it will charge max and burn up and make wires hot. or if there is a short at that old ammeter.. it will make some wires hot.

either way. if the ammeter stays deflected when bat out. replace it and we can troubleshoot it. ammeters today are really a shunt voltmeter anyway. ie.. vdrop across a shunt... etc.

 

[94BULLITT]

Are you sure you hooked the regulator up right?

 

[Midniteoyl]

Agree with soundguy.. Ammeter is bad. Short to ground.

 

[tmac196]

The tractor will start and run with the ignition key on and the battery connected whether or not the genie and/or the VReg are connected.

I will obtain a new ammeter today, I hope.

Were the wires connected correctly? Well, I took the time to carefully reconnect them the way they were once I had the gennie repaired and installed the new Vreg 7 weeks ago. At that time, per the manufacturers instructions, I polarized the gennie and this process seemed to work correctly. When the engine had enough revs, the Ammeter strayed to the right indicating current flow charging the battery. I did not feel the Vreg at that time, so I don't know if it was hot then.

While on the topic of wiring, how about a simple primer wiring discussion of what wires go to what structure. Gennie has ARM, FIELD and GROUND and these are wired to what, specifically? Vreg has ARM, FIELD and BAT. I can carefully chase the wires in the "harness" down when I reassemble and test the system to avoid wiring mistakes with some advice from all of you.

Thanks, again, for the help.

tmac

 

[MGBBob80]

I found these on the N Tractor Club website and thought that you might find them useful. N Tractor Club.

View attachment 8N- Wiring- Diagram-by-Jim-Lawrence.pdf View attachment Testing-Replacing-Polarizing-8N-Voltage-Regulator.pdf

 

[tmac196]

Thanks, Bob. The second PDF was helpful, but the first was for a 12 volt system. I am still running a 6v system in this tractor.

tmac

 

[MGBBob80]

Thanks, Bob. The second PDF was helpful, but the first was for a 12 volt system. I am still running a 6v system in this tractor.

tmac

Whoops... Sorry about that - I did know that you were on a 6 volt system.

I do have another set of schematics that show wiring diagrams for several Ford tractors including the 8N. Unfortunately, it's about 2MB in size and I'm not having any luck uploading it. Drop me an email if you want it and I'll attach it in my reply. Email is bob.finley.usn@gmail.com

 

[farmer jann]

I own a 53 8N and always had to charge the battery,(even if I disconnected the battery between uses), I rewired everything, got a brand new 6 volt battery, charged it before I installed it and IT was dead the next time (about 3 days) later. I called a place that services alternators and generators and they asked me to bring in the generator for a bench test. The guy was so nice, said he would fix the thing and to come back I 2 days to pick the new polarized generator up. As I paid for the (repolarized) generator, he asked me if I realized that my tractor was a positive ground system. I looked at him, I remarked that I had changed out every battery since just the way it had been connected when I found it. I was amazed. For as long as I could remember, the 6 volt battery had been hooked up BACKWARDS! I thanked the man for the bit of info. I replaced the original voltage regulator with a new one about a year ago and it starts right up!

 

[Soundguy]

not surprisingly. arm to arm, field to field, ground to ground ( redundancy ), and bat travels off into tractor harness.

 

[tmac196]

Update:

Went to the local Agri-parts store and purchased an ammeter which the clerk had to blow the dust off as he handed it to me. Here is the package tag. The clerk couldn't tell me if voltage mattered as far as if ammeter would run off a 6v or 12v system:



Next, I performed contuinity testing on the wires between the gennie and the VR and identified the Ground, Field and Armature wires. At the VR was a fourth unmarked wire which presumedly is attached to the BAT terminal on the VR. We continuity tested this and it had continuity with the battery terminals.

The gennie was bench tested on Friday at the repair shop and pronounced "normal".

The battery had been charged for three days and tested 6 volts on the button.

After wiring connections were made we turned the ignition key and observed the ammeter needle deflect as it usually does to the left. The tractor started and ran well. The ammeter never strayed into the positive side even with engine revs. Presumedly because the battery is fully charged?

The VR never became hot.

So have I fixed my problem or am I just kidding myself and running for a few days off a fully charged battery? Any suggestions for confirmatory testing would be welcome.

tmac

 

[Soundguy]

full field the genny and seeif the ammeter strays to the right.



ie.. ground field and then bring rpms up..

 

[tmac196]

full field the genny and seeif the ammeter strays to the right.



ie.. ground field and then bring rpms up..

SG,

I assume you want me to just remove the field wire from the gennie and ground it. Leave the armature wire on which will allow the gennie to charge at full output when rotated and should, if all is correct and functional, peg the ammeter to the right ("+") side, correct?

Jes' checkin' to see if I understand you correctly.

tmac