1940 Ford Generator 'issue'

wspiker

wspiker

Senior Member
I have a 1940 Ford. What does it mean when the motor is running and you disconnect a battery cable and the engine dies? I checked the generator and it appears to be working; I changed the voltage regulator, still engine dies?
 
Did you polarize the regulator? I wouldn't recommend removing the cable, I have done it and must have been lucky enough not to damage the system,
remove the belts and wiring from the generator connect it to the battey and see if it motors this should at least tell you the generator is working , however it may not have adequate out put , check for proper grounding of the generator and regulator, proper grounding is the most over looked problem in electrical trouble shooting and secondly dirty connections are sometimes the culprit. the generator and regulator need to be tested with the proper equipment, years ago we tested the generators by bypassing the regulator and load testing with a carbon pile resistor and ampmeter, serious damage can result if not done correctly.someone here can probably suggest a different method of testing, just be careful we don't need any of our early iron burned or anyone hurt, I have the test procedures in an early motors manual , I would gladly fax it to you but my fax isn't working at the moment.
Hope this helps,
Fordestes
 
why is it that when people have starting or charging proulbems they don,t use a volte meter & amp gauge to check there proulbem. there cheap they take the guess work out of the proulblem & there simple to use & save money.
 
Why are you removing the battery cable? There are better and safer ways to check out the charging system.

To answer your original question, it is normal operation that the engine dies when you remove the battery cable on a Ford car.
 
Thank you. I do have a very good Triplett voltmeter and "Repair Manual Generating and Starting Systems, 1933-1947". A fellow V-8er came over a couple of days ago and we followed test procedures and changed the Regulator. I thought that the disconnect of the battery would be 'the litmus test'. So, I tried it and the engine died. That is why I am seeking any input. My guess is that it is the regulator that could possible be the problem. A couple of things you stated I will be checking, i.e. I will polarize and check the regulator being grounded. The regulator is attached to the firewall with the rubber base and brass fittings purchased from Bob Drake. This appears to not allow the regulator to be grounded to the firewall? I got the impressions that is the purpose? Should I remove these rubber/brass grommets and bolt the regulator directly to the firewall? Thanks again for your input.
 
Leave the regulator connected to the three rubber cushions, there should be a screw in each connecting the cushions to the firewall, this physically mounts the regulator to the firewall and gives it some cushion from vibration. Yes you do want to add a ground wire from under the head of one of the mounting screws to the regulator case. Check the lower most perimeter of the regulator for a hole for a screw that is used to secure a ground wire to the regulator.
 
Modern systems with alternators & diodes built in will actually run if the battery is disconnected with the engine still turning as long as the alternator is functioning correctly. The older three pole regulators all have a cut out as one of the three poles. The cut out will close if the generator is working and open when either the gen is not working or the battery is disconnected.

The early designs of the three pole regulators all had rubber vibration absorbers and a grounding terminal on the regulator frame. The modern replacements did away with the vibration absorbers so a ground terminal was no longer necessary as long as the frame, body, and engine are electrically bonded together for a good current return path.

Kerby
 
Thanks. I have a "1940 Restoration Book" issued by Early Ford V-8. I looked at the regulator picture and saw a ground wire. I am on my way to Sacramento Vintage Ford to get parts to make a 'somewhat attractive' ground wire.

In my mind, the only 'litmus test' is if the battery stays charged while driving the car. That way the car will run off the generator and not just the battery, which it has been doing.

Thanks again everyone for your help.
 
a gen will work with a dead batt a alt will not .thats why when you had a car with a dead batt & gen you could push start it . a car with an alt & dead batt you can push to alaska & it will not start a gen has rezuisual magnatisem .a alt. needs to energized
 
Thats pretty much true but it depends on what's wrong with the battery. If it is still electrically connected on the internal cells then current still has a path to flow. You still have to have enough juice to make the ignition work if you are hand cranking or rolling it down a hill for a jump start. An alternator has to have some juice to get started or it won't work.

I used to drive my Model A a lot and it worked fine in the day time but at night, it was just a matter of time till it just flat ran out of juice to keep the lights going no matter where you put the 3rd brush. If you shut the lights off it would charge back up but its a little scarry if your way out in the sticks wondering if it will make it back to town without quitting or hitting a cow or somethin.

Kerby
 
Here's a real low tech test for the gen, I do it a lot, on new rebuilt, (or old used) to see if it's going to work...
Hook the generator up to a battery like it's a motor, I would use positive ground, you can use 12v... Hook up the negative cable to the wires leading right out of the generator... The generator should spin, "motor" if it's working... Oh, yeah-take off the fan belt-
Karl

I just put this up on another thread this AM, thought it would fit here...
 
It appears that my "issue" was that the Regulator was NOT grounded! I accomplished that per Fordestes above suggestion, and everything is working great, i.e. AmpMeter gives proper reading and the battery is being charged............... It does not run the battery down after driving twenty miles...............everything appears to be good.

Thank you all for your replies and assistance..................
 
I like a ground wire direct from gen case to reg base (Ford did this after '40) and an extra from that to the bat ground cable. Engine ground path is far too messy, with dirt, paint, rubber, gaskets, etc. offering potential losses everywhere...
The car should run with cable yanked (though this is electrically messy as battery drops out of circuit, not really advisable!) IF engine RPM is high enough...regular idle will be a touch low, and if you choose to try this you need to pull out the throttle button a bit.
There are better tests, with gauges employed or without, including a simple procedure to "full-field" the generator...this one will show if generator is good even if reg is kaput.
I compiled a bunch of Ford and Echlin test information on the charging system over on the HAMB, running tests and tests of the pathways within the gen. I even included the once common, slightly scary, field and armature tests using 110 volts to find potential problems. I also posted the polarizing procedures...you have to research this a bit as half the people you go to for advice will give you the light duty Delco polarizing technique, which is incorrect and potentially destructive on the Ford type circuit...
Will see if I can locate those tests.
 
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