New alternator?

Electrical & Ignition

  1. tbm3fan

    tbm3fan Senior Member

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    Last weekend I swapped the 73 Polara and the 67 Park Lane around so I could get the Polara out today, gas it up, and take a drive. Started no issue and only ran it a few minutes then. So this morning started the car up without issues ready to go.

    So going to a gas station 1.5 miles away is obviously bad luck for me. Last summer the Focus ignition tumblers decided to give up the ghost. Only 10 years after most of them do and I was stranded till AAA towed me home. Car fixed in 20 minutes by removing the tumblers. Two months ago drove the Cougar for gas and it wouldn't start after gassing up. The problem was a flooded engine with gas all over the intake. Towed home and a 15 minute float adjustment.

    Today it was the Polara's turn. Gassed up and the car turned over but wouldn't start. The turning over seemed wrong to me right away. Sounded slower, with less power you could say, and the flickering oil light was dimmer. Crap, the battery? Well it is only 3 years old. Dead from sitting 3 months? Push the car out of the way of the pumps, again, and wait for AAA.

    Whatever the guy uses to hook to the battery to check health I need to get one of those. He says the battery doesn't look to be the problem and is guessing the starter. The short drive drained the battery enough not to start. Hooks his power pack up and it starts right away. Then he uses either what looks like a cell phone to hold near the battery to check charging voltage. It is 12.1 volts. Now I have to be able to get home without the car dying as a tow means no riders in the cab around here and I have my son with me. Just a fricken" great day! Gotta say it ran great for those few minutes and wish I could have gotten more.

    So I gather I have a 41 amp alternator based on the FSM? Where is it suggested to get a replacement? Any old auto parts store or elsewhere?
     
  2. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    If there is an old line rebuilder in your area, I would suggest you take it to them and have yours rebuilt. The alternators at Car Crap and AutoBone are mostly junk, they are rebuilt overseas and usually only the part that has failed is replaced. Might also try NAPA as they might still have the quality rebuilt units available.

    Dave
     
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  3. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    It could be the regulator. Easy to check. Unplug the green wire from the alternator and leave everything else plugged in. Now run a jumper wire to ground from the field connection you just unplugged on the alternator.

    You'll need a voltmeter now. Even a cheap one will work. Start the car and turn on the headlights to create a load so it doesn't overcharge. Check the battery voltage. It should be over 14 volts. If it isn't, it's the alternator. If it is, it's the regulator.
     
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  4. ayilar

    ayilar Senior Member FCBO Gold Member

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    Assuming it is the alternator, I would go with @Davea Lux and get a good old rebuilder to fix your original one. Here is why.

    A year ago, I searched far and wide for a 45-amp round-back alternator for Medina, my '71 Monaco, last year -- thinking the alternator that came with my car was not the correct one (because it had been repositioned incorrectly by a previous owner; that turned out to be the wrong guess, but I did not realize this fact till I had already bought two and is beside the point).

    Back to the two I bought. First, I only found two places that sold 45-to-50 amp units. Everyone else was hawking higher-amp units (60, 75 or more), and my car was not built for them. This said, why did I buy two and not just one? Well, I found two places that said they had 45-50 amp round-back alternators. The first one sent me a square-back unit, though, and it would not fit in my car (close, but no cigar). Rather than go through the hassle of shipping it back, I have kept it in case I ever buy a '72 or '73 Plymouth or Dodge.

    Bottom line, one can find a reman square back 45-50 amp unit, but whatever I found was not cheap (I paid over $100 if memory serves). I would be happy to resell mine to you if you wanted to (in that case, just let me know), but then again, I think you're better off having yours fixed.
     
    Last edited: May 20, 2020 at 8:18 PM
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  5. tbm3fan

    tbm3fan Senior Member

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    I just went out to do the check you mentioned. Needed to get close to see which wire was black and which was really green as the green looked black. Went to rub the wire to the top position field brush clip, to see if black or dirty, and the whole wire moved. What, that long clip had disconnected from the vertical spade terminal. How the hell did it do that? Well the car started, without help amazingly, got the rpm up and the battery read 13.8 steady volts.

    Now I don't know how long this alternator can last now that the wire is back. With my Fords, I have three spare Autolite marked alternators, from 15 years ago sitting up my parts shelf just in case. In those I replaced the bearings and brushes my self at the time. I have a box full of Ford stators I picked up many years ago which were all unmarked as to amps so I can't sort them.
     
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  6. 65sporty

    65sporty Old Man with a Hat

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    Nice easy fix, you may want to find a spare if your worried about this one lasting.
     
  7. stubs300

    stubs300 Senior Member

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    You never said, so I have to ask? What was the alt gauge reading while it was running before it died? Good Luck
     
  8. tbm3fan

    tbm3fan Senior Member

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    One of the first things I did when I got the car was to bypass the ammeter gauge
     
  9. cbarge

    cbarge World Famous Barge in a Budget FCBO Gold Member

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    Which is good.
    If you want to monitor the charging system a simple aftermarket voltmeter can be installed.

    Whenever I suspect anything I just use a multimeter and with engine running I test it at the battery.
     
  10. Mike66Chryslers

    Mike66Chryslers Well-Known Member

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    From what you describe, it sounds like your entire problem was that the field wire became disconnected from the terminal on the alternator. Are you still suspecting that the alternator is bad?
     
  11. stubs300

    stubs300 Senior Member

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    That still doesn't answer the question as to weather your system was charging or not, which would lead to what's going on with the system and not chase shadows. Good Luck
     
  12. cbarge

    cbarge World Famous Barge in a Budget FCBO Gold Member

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    Must be a politician,LOL!! :lol:
     
  13. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    '73 already has a shunted ammeter. No need to bypass it. Won't hurt , but with only a little bit of current running through the ammeter, there's no reason either.
     
  14. tbm3fan

    tbm3fan Senior Member

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    I believe I said the running car was getting 12.1 volts at the battery. When off the battery showed 12.08 volts not the 12.8 one could reasonably expect. After that I found the negative field terminal wire disconnected from the alternator. Once connected the running car was now getting 13.8 volts at the battery.

    I now believe the alternator is good to go.
     
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  15. tbm3fan

    tbm3fan Senior Member

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    Good to know. I don't recall that Allpar article being very specific about what years were bad and which were not. I'll pull it off and see what it shows on a running car with a low charged battery for reference.

    Wait take that back as I was just out there and saw I removed it sometime ago. Probably because of something you said. So when running the alternator needle is just slightly towards charging barely touching the white line for middle. Now have the battery hooked up to my charger as it is still 12.1V. Yesterday couldn't get the + battery terminal off and today a slight turn and it was now loose. Go figure.
     
    Last edited: May 21, 2020 at 8:02 PM
  16. Mike66Chryslers

    Mike66Chryslers Well-Known Member

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    Just a note for future: If you're not entirely removing the battery from the car, it's better to disconnect the negative terminal than the positive terminal. If you are removing the battery, disconnect the negative terminal first, and install it last. That way, if you accidentally touch the wrench against the body, there is no chance of causing a spark. It's also less likely that any sparks generated while removing or installing the terminal will damage any electronics.
     
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  17. tbm3fan

    tbm3fan Senior Member

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    I have always disconnected the negative first.
     
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  18. tbm3fan

    tbm3fan Senior Member

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    After finding that loose connection I put the battery on my automatic charger using the 10 amp choice. Well after 12 hours on the charger, the needle reading almost done but the light never saying complete, the battery reads 11.9 volts. I know that is not good and probably sulfated badly. Wonder how long that connection was off and the battery carrying the load? Anyway, looks like a new battery after three years.