1940 6 volt system failure to charge

T

Tinkerer77

Junior Member
Howdy all,
I know this has been discussed in other threads; but I cannot seem to get my 6 volt charging system to work despite various sources of advice.
The car: 1940 Ford Tudor Sedan
What’s been done: Complete new wiring harness from Vintage Ford, new Napa Commercial 6 volt battery, new cables, solenoid, rebuilt generator off eBay, NORS “Holley” regulator (after trying el-cheapo blue top) etc.
The problem: After all of the above, generator appeared to be working initially. Battery gauge was heading towards green. Then while out and about for a short jaunt, starts hanging out in the yellow until discharging into red—causing engine ignition interference that doesn’t exist when fully charged. Generator gets so hot can’t keep my hand on it for long. I have used both a multimeter and analog diagnostic gauge and there’s little to no charge coming from the generator into the system. It’s like no matter what, refuses to ‘arm’ n charge. All help is appreciated, generator/regulator is currently at a shop getting tested; but previous generator had the same issue.
 
Ensure that all grounding points are clean, secure, and free from paint or rust. Poor grounding can lead to charging issues. Check the battery ground strap, engine ground strap, and any grounds associated with the generator and voltage regulator.

2. Polarize the Generator
Whenever a generator or regulator is replaced, the generator needs to be polarized. Here’s how you can do it for a Ford 6V positive ground system:

With the engine off, connect a jumper wire between the ARM (armature) terminal and the BAT (battery) terminal on the voltage regulator for a moment (a brief spark indicates polarization). Ensure correct polarity.
3. Voltage Regulator Adjustment
Even new or NOS (New Old Stock) regulators might need adjustment. The regulator controls the charging rate and can sometimes be misadjusted or faulty out of the box. A specialist shop should be able to test and adjust the cut-out relay, voltage, and current regulators properly.
 
Thank you for the response! I forgot to mention I sanded down to bare metal on the firewall mounting points for the regulator, cable, solenoid etc; and the back of the generator mount where it attaches to the intake manifold. I also polarized both the regulator (first—got a spark), and the generator (second—no spark…). I’ve polarized any time anything was disconnected.
 
With the engine off and ignition on, the gauge registers the battery status via colors: red (low), yellow (getting there), green (happy) and an extreme yellow (overcharge). I can’t remember whether it registers in the green with the engine off and just a fully charged battery; but it probably wouldn’t, as 7.2-7.5 volts is required to indicate a good charge.
 
Tinkerer77 said:
With the engine off and ignition on, the gauge registers the battery status via colors: red (low), yellow (getting there), green (happy) and an extreme yellow (overcharge). I can’t remember whether it registers in the green with the engine off and just a fully charged battery; but it probably wouldn’t, as 7.2-7.5 volts is required to indicate a good charge.
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Is it in the RED with the engine off and the ignition on? If so, how much in the red?

Battery-Charge-Gauge-600x425.jpg
 
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Cutout relay in the regulator on my "56 bird refused to open. Generator was trying to "motor" at low rpms. I don't think your genny is going to take too much of that before failure.
 
If you still have the original 1940 generator, you are fortunate. This style generator was only made 1939-1941. It has a single Field stud on the side of the case, in 1942 they added a second ground stud. Apparently Ford determined that the mounting flange alone did not proved an adequate ground. The point of this is.- be certain the generator ground path back to the battery and regulator is good with no added resistance due to paint or rust.


This photo shows an April 1940 date coded generator with the single side stud.
 

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My 40 gen is in the shop again. Owner thinks it may be the3 field coils. I hate to go to an alt as this engine has a lot of early speed parts. Almquist intake, chrome 97"s, Kogel heads.
Paul in CT
 
1931 flamingo said:
My 40 gen is in the shop again. Owner thinks it may be the3 field coils. I hate to go to an alt as this engine has a lot of early speed parts. Almquist intake, chrome 97"s, Kogel heads.
Paul in CT
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If you are interested. I can rebuild your generator properly , including new fields. The 1940 generator pictured above is one I rebuilt, keeping the nice original paint. It is for sale too. Glad to help. More info on it here:
https://www.fordbarn.com/forum/showthread.php?p=2317663#post2317663
 
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I went through hell with the charging system on my '50 before finally finding a voltage regulator that functioned properly out of the (old) box.
 
ndnchf said:
If you still have the original 1940 generator, you are fortunate. This style generator was only made 1939-1941. It has a single Field stud on the side of the case, in 1942 they added a second ground stud. Apparently Ford determined that the mounting flange alone did not proved an adequate ground. The point of this is.- be certain the generator ground path back to the battery and regulator is good with no added resistance due to paint or rust.

Thank you for the responses. Interestingly enough, the generator that was on the car when I bought it was equipped with the ground stud. The generator I bought off eBay appeared a ‘40 original. I’ll reach out for your generator rebuilding/swap; but the one I have as a core is the one with the ground stud at present.
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**UPDATE**
Just went to the local shop and their verdict is the armature is bad, burned in a couple spots where the brushes were obviously arcing. The brush springs also appeared not to have been replaced (weak tension) and the field coils were also suspect. Bottom line, buyer beware off eBay—even if it looks pretty. The guy advertised it as “rebuilt generator”, and most laymen would expect precisely that: all serviceable components replaced/reconditioned. Thank you all for the replies.
 
Sorry to hear that, ebay beware. That's why I post a detailed description of the work I've done, show a photo of the generator before final assembly as well as after, and a video showing it running on my test bench.

Steve
 
ndnchf said:
Sorry to hear that, ebay beware. That's why I post a detailed description of the work I've done, show a photo of the generator before final assembly as well as after, and a video showing it running on my test bench.

Steve
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Yes. “Rebuilt” should entail all internal components replaced, not just a paint job, brush change and filing down the armature (if that was even done), as this appears is my situation. It’s my understanding in some circumstances even a special paint is required, to prevent metallic particles in some paints from causing potential shorts when used in electrical components.
 
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