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Hot Rods Alternator flaking out?

Discussion in 'The Hokey Ass Message Board' started by jhutch, May 15, 2017.

  1. jhutch
    Joined: Jul 18, 2011
    Posts: 137

    jhutch
    Member

    HI all,

    I attempted a search but I'm still not clear so I figured I'd throw an easy one out for you.

    I broke the alternator bracket on my 62 Bel Air (327SBC) and I replaced it but it's never really be "right" since. I'm using the Mr Gasket header 2 piece header bracket and I had to try out multiple v-belts to get it going but I finally got it all sorted and I think aligned properly. I do not have have AirCon/heat in the car or a big stereo (just a little in-dash unit), HEI, and I currently have LED headlights - everything else is stock.

    I have only the 1 positive power wire connected and the wire to the volt meter - I DO NOT have the wire from the 2nd port on the top of the alternator to the positive - I've read it's not required and that seems to be the case but maybe that will help normalize the problems, I'm having?

    My current issues are the following:

    1) It's a 1 wire setup. Car starts fine and the Alternator energizes properly once over 1200 rpm or something like that. My voltage meter in the car shows it putting out about 14 volts. Once the engine is warmed up and after driving about 10 miles or so, the voltage will drop to about 10v and bop between that and 12v. The car continues to run fine with no issues - in fact, it seems to be running better than it ever has! Is it normal for the voltage to drop like that? Perhaps assuming the battery is fully charged since there is little draw on it?

    2) the Alternator does sound a bit noisy. When I had the belt setup so it didn't squeal it sounded like it had a bag of rocks in there. When I backed it off a bit, it still sounds a little noisy but now when I get around 4k the belt is squealing - I could perhaps not have it 100% aligned front/back with the water pump and balancer? Or could this be a symptom of the Alternator just letting me know it's on it's way out?

    3) Car always cranks over fine when cold. Once hot, it starts slow - like a whump, then a pause then a whump and it fires up. I would suspect this could be the battery running low (bullet 1) but if I leave the car to cool for a long time it will fire up normally.

    Thoughts? Opinions?
     
  2. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,581

    gimpyshotrods
    Member

    To me, it sounds like a faulty internal regulator. I do not like, and will not install one-wire alternators for this exact reason. I have observed far too many of them disengaging at lower RPM.

    The "it seems to be running better than it ever has" part may simply be that it is running without the load a (should be) charging alternator puts on the engine. (Free horsepower, old racer trick.)

    As for the mechanical noise, that may just be mechanical failure in the early stages.

    If it were me, I would toss the alternator and get a 3-wire one. Wiring is simple:
    [​IMG]
    Since the #2 wire jumpers back to the big post, it is really only like adding one more wire.
     
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  3. jhutch
    Joined: Jul 18, 2011
    Posts: 137

    jhutch
    Member

    so that green wire would go to my ignition and also to the volt meter? Would I need to wire in a relay?
     
  4. Times 2 ..Don't care for one wire alternators
    Somebody had put one on a stock 56 Pontiac I bought. It idled at about 500. Alternator wouldn't charge under about 1100.
    First time I took it out at night to a cruise deal, it ran the battery down, driving it from light to light.
    Took it off and replaced it with a big amp 70's GM unit.
    Used the 1 wire for parts.
     
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  5. No, from the warning light or volt meter. You should have remnants of a voltage regulator there in the harness.You can pick it up there. Just needs a few volts to trigger the internal regulator.
     
  6. 62 was still generator, I believe. Probably ought to find a wiring diagram.
     
  7. jhutch
    Joined: Jul 18, 2011
    Posts: 137

    jhutch
    Member

    Hmm. I do have remnants of the external regulator. I'll check it out and see what's there. The alt did have short voltage sensor wire initially but it broke and I didn't replace it (months ago). Perhaps I need to reintroduce that see what happens. on the "1" in the diagram is where my volt meter/light is currently connected. The positive is connected to the old regulator which is wired to the positive on the battery.
     
  8. Green wire goes to "hot when key on" source, ignition, and there is no relay. If you want to use the warning light, then the light is between the ignition source and the alternator. The volt gauge runs from a ignition wire/source (you could use the fuse panel for this) to a ground.

    One wire alternators will not charge at low RPM's that is the nature of the beast.
     
  9. jhutch
    Joined: Jul 18, 2011
    Posts: 137

    jhutch
    Member

    I should clarify - I'm noticing this voltage wandering at highway speed / about 3k RPM. It actually seems to head back closer to 12v when I pull off the highway.
     
  10. jhutch
    Joined: Jul 18, 2011
    Posts: 137

    jhutch
    Member

    So if I'm understanding you the OG voltage light would go to port 1, but the aftermarket style voltage meter would connect to the ignition wire or the 12v feed that ties to the battery? Is that correct?

    Sorry if I'm being thick - I do need a service manual for this old girl, but this is also how it was wired when I got it so I'm trying learn/understand the proper way. I can confirm that this electrical system has been hacked up a bit so there will be project in the future to really dig thru it.
     
  11. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 4,884

    Ebbsspeed
    ALLIANCE MEMBER

    You absolutely need the sense wire connected, unless there is an internal connection. That wire tells the alternator how much voltage to put out. Ideally it is run all the way to the + battery post. When it is connected right at the alternator, the voltage drop between the alternator and battery is not "seen" by the alternator, so the ideal charging voltage will be present at the alternator terminal, but less than that at the battery.
     
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  12. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,581

    gimpyshotrods
    Member

    True, but old man GM did not wire them this way. Every one that I have seen of the 10si/12si variety has the the connection as a splice, less than 12" from the back of the alternator.

    Yeah, not "perfect", but still totally functional.
     
  13. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,581

    gimpyshotrods
    Member

    [​IMG]
     
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  14. jhutch
    Joined: Jul 18, 2011
    Posts: 137

    jhutch
    Member

    Thanks all. I'll check the wiring and document what's going on. I guess if the bag of rocks sound still happens after I adjust to fix the squealing I'll be replacing it anyway but at least I'll know I have the proper wiring.
     
  15. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    Member
    from Wisconsin

    If you have a volt meter, it doesn't need to be connected to the alternator. You can measure voltage anywhere in the system. An idiot light gets connected to the alternator regulator.

    There are different regulators for one wire alternators. We used them on forklifts which often sit and idle. We got them from an alternator shop in town and almost anyone that builds them will know which one to use. It will start charging at 500 alternator rpm and have good output at 1000 rpm. The alternator is turning at least 3 times faster than the engine.
     
  16. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547

    stimpy

    I agree with him , the so called simplicity of the one wires have created more problems than taking a few extra minutes to do it right . but even the oems say run the sense wire to the battery or starter stud ( where the main harness ussually hooks in ) for a cleaner /truer voltage read ( and if it wasn't true they wouldn't waste the .05 -.10 cents to put the extra length of wire in ) . as it will read all the draw vs what its putting out , plus they use the battery as a filter .

    as for they didn't do it , Gm has popped back and forth on this , MY O/t 96 truck has it right to the battery , my o/t 98 car has the loop and when you turn the lights or fan on high on it flickers and Dims for a second ( which cannot be good for the computer , and the alternator has been replaced with a OEm new one , put the wire on to the battery and no problems . and at my refresher they said to install a bypass to the battery if the car has "charging or spike " problems.
     
    Last edited: May 15, 2017
  17. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547

    stimpy

    some of the units if you look closely also have a 8-9" vs the 5-7" lower pulley to keep the speed up while idling or over drive off the fan pulley ( step up pulley ) as one of my co workers found out the hard way when he replaced it with a car pulley ( its a turdota engine so its the same parts right ??? (NOPE ) . drove me nuts for a month trying to figure it out ..
     
  18.  
  19. jhutch
    Joined: Jul 18, 2011
    Posts: 137

    jhutch
    Member

    I think I misspoke when I said 1-wire. I checked the wiring last night. I ran a shorty from "2" to the positive on the back of the Alternator. I saw your notes about running it all the way back to the battery but I checked the voltage drop with a meter and it's almost nothing so it should be ok. I can't seem to locate the proper color line that goes to the idiot light/ignition switch so for now I have nothing connected to "1". It appears there will be a wiring project in my future.

    I found an informative video on youtube about this wiring too.
     
  20. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547

    stimpy

    being your running your car "old school " with minimum draw other than the starter and the ignition , you should be oK with the sense wire to the alt post , but one thing to remember you do need more than 12.v to "charge" the battery your gauge should read 13.5 for it to be charging , Crazy Steve ( hes a Electric Nerd here ( no offense Steve) ) wrote a nice thread on the subject , with Electric info in it that is a must read .
     
  21. jhutch
    Joined: Jul 18, 2011
    Posts: 137

    jhutch
    Member

    I'm getting about 14.5v at the battery.
     
  22. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547

    stimpy

    then its doing good ( charging to make up the start draw) . it will taper back to 13.5 when the battery is getting near fully charged . only time you will see below this is when its not working .
     
  23. jhutch
    Joined: Jul 18, 2011
    Posts: 137

    jhutch
    Member

    Yep. that's what i was reading with my volt meter when I checked it. It's about a 0.25v loss between the battery and the alternator.
     

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