Cutout Not Cutting Out?

U

ursus

Well-known member
I am not getting any ammeter wiggle when turning on or off the ignition or turning on/off lights so suspect that the ammeter is dead. Everything else is working OK. My main concern now is that there is no way to tell if the cutout is closed and draining the battery (This happened before once, so I'm wary of it).

I put multimeter probes on the input and output contacts on the cutout and get 6.5 volts when the engine is running and 6.3 volts when the ignition is turned off. Does the latter reading mean than the cutout point are stuck closed?
 
seems that way — original cutout or one of the reproduction ones
wack it with plastic hammer,hammer handle,something and see if the result changed
I put in a diode many years ago to cure the possibility of sticking after it happened a couple times— took out the winding and contacts drilled a hole in the frame and put in a diode salvaged from first generation Delco alternator that I found behind a gas station
 
Could be OK. The resting voltage of a lead-acid battery is around 6.3 volts. If it was sticking it would be a lot lower. To make sure take the lead off of the cutout and then measure the voltage at the unconnected lead. If the cutout is OK it will be the same voltage connected or not connected.
 
unhook both sides of the cutout, in from generator, and out to the wire. use your ohm meter to test it . if you have continuity then the cutout is not cutting out.
 
Hello, had a cutout switch stick closed , generator turned into a motor, horrible squeaky noise , trying to turn the fan belt ,didn’t take long to figure that out. If they stick open don’t get a charge.Amp meters were discussed on earlier posts with some of the repro not being the best. Was a link to a better quality one,but I couldn’t find it.
 
Having refurbished hundreds of original Ford cutouts I can say that it is extremely rare for cutout points to stick together. It happens far less frequently than people think. What does happen is internal insulation deteriorates and breaks down causing a short.

If you are interested in servicing, testing and adjusting a cutout, check out my video:
https://youtu.be/rnuukBeJ6Zs?is=gsGQUoahHZ56KwUl
 
These slides may help. I recommend that you use the solid state Diode cutout. However, the ultimate fix is to run an alternator. Also, some reproduction ammeters are not made like the originals, and may not work correctly.
 

Attachments

  • Cutout Cover – Make It Removable 179kb.jpg
    Cutout Cover – Make It Removable 179kb.jpg
    59.9 KB · Views: 50
  • Cutout Roadside Fix 144kb.jpg
    Cutout Roadside Fix 144kb.jpg
    47.6 KB · Views: 52
  • Cutout Roadside Fix 162kb.jpg
    Cutout Roadside Fix 162kb.jpg
    53.8 KB · Views: 50
Add to Bob's fix, if you insulate the contacts you must also ground the generator output. Gen will burn up if run with no load. Grounding the output keeps it from developing damaging voltage.
 
Ford made a change to the ignition coil circuit in an early service bulletin. The ignition coil was put into the load side so that the ammeter could read it. When cranking the engine over, the coil will be an intermittent load seen on the meter as the breaker points open and close. Once the engine is running, it should indicate the constant load of the ignition system as well as the charge amperage. If the ammeter is showing a discharge, the indication would be the load without generator compensation. Modern ammeters are hit or miss depending on quality of the replacement part. The originals were very sensitive so they could read the low amp readings whether in charge or discharge state. Turning on the headlights should show a pretty good discharge if the generator isn't on line. Test the ammeter this way to make sure your getting a reading one way or the other.

A good ammeter will indicate that the generator is on line. With a modern volt meter, it should indicate an output to the system that is above the battery voltage. Ford dealers generally clipped a sensitive ammeter test unit between the output of the generator and the wire to the terminal box in order to test and adjust generator output. They may have used a volt meter as a general operation just to see battery and system voltage but it should to be a sensitive unit as well.

The cut out senses battery voltage so that the relay will turn the generator on line as soon as the generator voltage output rises above the battery voltage. The residual magnetism in the field coils is what starts the generating process as soon as the engine is rotating fast enough. It's important to have very good battery and generator connections. The battery is the only voltage regulator in the 3-brush generator systems. The individual electrical loads in the vehicles electrical system also help balance out the voltage to a certain degree. If the battery has a week connection or an internal problem then the generator can have excessive output and do damage. Insure all this stuff is good anytime you have charging difficulties.
 
Thanks to all for the help with this! I removed the cutout and tested it on the bench and found zero continuity between BAT and ARM contacts. I also found 36 ohms resistance between the ARM contacts and the base. I tested some other cutouts that I had picked up at swap meets and found some with zero continuity between base and ARM and some crusty old Ford cutouts with 50 ohms resistance, which is better, I think. Next, I will disconnect the output lead and check for voltage output with the engine running.

I hope this report makes sense. Any comments on this are welcome!
 
Do not disconnect the generator from the battery and load or the generator will quickly destroy itself. Use a jumper across it like Bob's second method.
 
If you do take the connection to the generator off, just remember that it is completely unregulated as previously stated. A momentary check will show unregulated output so be ready to shut it down quickly.
 
You must log in or register to reply here.
Back
Top