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Detroit57Bird

1957 Generator question

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Bought a super nice 1957 Thunderbird last year. Everything is great but it has one odd behavior. The previous owner installed a kill switch on battery because with the car off intermittently the battery will drain down very quickly with the generator heating up and smoking. Any thoughts on what the problem might be?

Also second general question - I saw note from 1957Birdman about blue regulator versus black. How to know whether parts are correct or not? For example I think the carpet may be incorrect.

THANKS!

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Sounds like the cut out points in the regulator are sticking closed.

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I'd suggest the generator needs a rebuild. Sounds like a bearing or combination bearing, armature shorting against the stator issue. A quick "free" charging system analysis at one of the chain auto parts stores or auto electric shops should reveal the exact cause.

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I would bet that your problem is a bad voltage regulator. I would have the generator checked first to be sure that it is okay. Assuming it is, then get a new regulator and install it per the instructions in the 1957 Ford and Thunderbird Shop Manual.

As for the blue versus black voltage regulator, the blue just means that it is a modern Motorcraft regulator and not an NOS one. That is easy to correct with some gloss black spray paint and the appropriate decal, available from the T-Bird parts suppliers.

Good luck and let us know how what fixes the problem.

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Yes, I agree that a faulty voltage regulator caused the generator to "smoke."

When the generator smokes, consider it "cooked." With the ignition key OFF and the battery hooked up, the battery terminal of the voltage regulator is always "hot," (As is the horn relay; brake switch power wire, & the clock feed wire.) If the the "cut in" terminal of the regulator doesn't "cut out" when the ignition key is turned off, the battery will short the generator armature. With this condition, the red "GEN" light can illuminate with the ignition key in the off position.

When the regulator senses that generator voltage is greater than the battery

voltage, the battery is out of the circuit and the red GEN light is extinguished. Consider the voltage regulator as a transfer switch, which regulates generator voltage, and keeps the battery charged with the engine running. When the engine stalls (key on), the regulator senses the generator is not producing power, turning the red GEN light on, signalling the battery to provide electricity.

Bob

McLean,VA

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Bob, thanks so much for the detailed msg. One more question, it seems the generator is still working as the battery seems to keep its charge. Also strangely sometimes the generator light stays on, sometimes not. I will replace the voltage regulator and see what happens. Is it likely the generator is still good not "cooked"?

Again thanks for helping a novice!

Mark

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With an intermittent GEN light, I'd recommend having the generator removed and tested for normal operation before you replace the regulator. The regulator can only regulate what the generator is producing in term of volts and amps. A warning light is telling you to look deeper into the problem If the generator is OK, then install a NEW regulator. A questionable voltage regulator should NOT be used with good or re-manufactured generator. Prior to alternators, which are actually generators, auto electric

shops always replaced generators with new regulators to ensure reliability.

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Thanks. It took me a while to get on this repair and longer to get out here and say thanks. The generator was damaged. I believe the source of the problem was the voltage regulator. 1) replaced the voltage regulator and 2) rebuilt the generator including repair to the end cap connection which look fried. I'm not sure there really was any problem with the commutator or brushes but replaced anyway. Didn't change the field windings at all. So again thanks for all the advice - I wouldn't have tried this by myself except for your advice and the great help of a couple real car guy friends at work. There turned out to be another wiring problem (which we fixed) but that is another story.

Recommendation: if anyone plans on replacing the voltage regulator - shop around. I found the same part from several sources from around $40 to $100! Delivery time was the difference so if you can wait... Generally i found Mac's to be the best price on the parts. If you live in southeast Michigan the guys at Bill's Suburban Alternator and Starter in Roseville have some "very experienced" (gray hair guys like me) that can help with older cars.

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One more note/tip for anyone needing to work on the generator. The messiest bit is the fact that one of the bolts holding on the generator, actually the bracket that holds the generator, goes through the water pump. Crazy. As a result yes you have to mess with removing it in order to remove the generator. After several rounds of trial and error, and therefore several round of draining the cooling system and refilling, I figured out you can get the bracket loose enough to get the generator off and NOT drain the cooling system. You do get some leakage from where the bolt goes through the water pump but a square catch pail under it works out. Basically you loosen the bolt, get the generator off the bracket and retighten the bolt until you are ready to put it back on.

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I have this exact problem with a '57 Tbird that is new to me. Existing battery died twice, so I replaced the battery and the new one died three days later. I charged it, sent it to my mechanic who can't replicate the problem. It has gone two weeks without draining, so the problem is intermittent. Unlike the OP, my generator does not smoke and the regulator seems brand new (blue). I am leaning towards replacing the generator with a rebuilt. Any thoughts?

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It's nice that Detroit57 came back and wrote up the solution. That said, an intermittent problem is tough, but I'd be looking at the points in the regulator. Any sign of pitting, erosion, or a generally gummed up unit, I'd replace it. When I bought my bird,I drove it home in the dark, about 70 miles. New battery. The headlights would dim till I couldn't see, then the regulator would kick in, back to bright, and then start to dim again. I was holding my breath, waiting for the engine to quit before those points closed. I made it, and replaced the regulator immediately. Problem solved.

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It's nice that Detroit57 came back and wrote up the solution. That said, an intermittent problem is tough, but I'd be looking at the points in the regulator. Any sign of pitting, erosion, or a generally gummed up unit, I'd replace it. When I bought my bird,I drove it home in the dark, about 70 miles. New battery. The headlights would dim till I couldn't see, then the regulator would kick in, back to bright, and then start to dim again. I was holding my breath, waiting for the engine to quit before those points closed. I made it, and replaced the regulator immediately. Problem solved.

I don't have a specific thought/suggestion beyond the comments made. One point of information - ultimately the cause of the problem with my car was (painfully) simple. Apparently someone had mistakenly reversed the wires from the generator to the regulator. The polarity was reversed - the positive was connected to the negative and vice versa! Ouch. Unlikely you have the same problem but you may want to carefully trace basic connections.

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Besides the wiring, there are only three items in the auto electrical charging/storage system. 1. The Battery 2. The Generator 3. The Voltage regulator (regulates amps also). Each of the items can be tested.

1. Charge the battery and have it load tested in or out of the car. If it holds 11 or more volts after a ten second load it's OK. 2/3. Remove the generator and voltage regulator and take them to

an auto electric shop for bench testing. Unregulated, a 12V generator can deliver 16+ volts DC. Depending on ambient temperature the regulator will regulate the volts from 13V-15.5 volts ... the colder the

ambient temperature the higher the volts to the battery. To prevent battery drain, the generator ... thru the regulator must maintain higher volts than the battery voltage. The maximum amp output

of the stock 12V generator is 30 amps and drops as the battery regains strength. If all of the previous checks out OK, make sure the wires go where they are supposed to.

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