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11 AC Lucus Alternator

Discussion in 'Electrics' started by roy willson, May 28, 2016.

  1. roy willson

    roy willson New Member

    Hello sorry if this has already been posted i have looked back but not found yet
    I have a 11 AC Lucas alternator and I am not getting any output
    Charge light on dash illuminated and no increase in voltage at battery when engine running before I go out and replace it is there anything else on a series one 3500 that I should look at before replacing alternator
    Thanks Roy
     
  2. Dave3066

    Dave3066 Active Member

    The 11AC charging system has 4 components. The alternator, a 4TR voltage regulator located in the passenger side glove box,

    [​IMG]

    a 3AW warning light relay located in the driver side glove box (might look a bit like this)

    [​IMG]

    and the early cars may have had a 6RA relay.

    [​IMG]

    I would check that all the connections are clean and secure first then try the 4TR voltage regulator. Failing that, the alternator brushes might need replacing or worst case the alternator windings might have failed.

    Dave
     
    roy willson likes this.
  3. roy willson

    roy willson New Member

    Thank you Dave I will have a look at the regulator
    I have had a look at the brushes and they look fine is there any type of bench test I can do to check the alternator before re fitting
    photos and locations are a great help
    roy
     
  4. sdibbers

    sdibbers Active Member

    The 3AW units are quite delicate. You can get modern solid state ones now (the plastic cube next to the one in the picture is one). You can test of the battery is charging by testing voltage while engine is idling. It should read ~ 13+ volts if the alt is charging. The 3AW unit just controls the charging light on dash.
     
    Last edited: May 28, 2016
    roy willson likes this.
  5. roy willson

    roy willson New Member

    With the alternator fitted and car running if I put a volt meter onto the largest connection on the back of the alternator I only get a voltage of 12 volts same as battery voltage
     
  6. roy willson

    roy willson New Member

    Update I had an hour before going to work alternator back on still no sign of increased voltage at rear of alternator no increase of voltage at aftermarket dash volt gauge and ignition light on
    Thanks to Dave's photos I found my 4 TR unit gave it a gentle tap and all came to life stopped again another tap back to life so a new 4 TR unit required I did check the connections and all seamed in order
    Thanks again Roy
     
    Last edited: May 30, 2016
    sdibbers likes this.
  7. DAV8

    DAV8 Member

    Hi Roy, Mine did exactly the same a couple of years ago (1971, 3500 auto) replaced the 4TR unit and all is well. I bought one from Holdens for about £55, unfortunately they are not the "Lucas" red ones but it works. Happy days.
    DAV8
    Dave
     
    roy willson likes this.
  8. roy willson

    roy willson New Member

    got my 4TR from wins international today not lucas original as above but as long as it works £ 49.36 plus postage which was next day
     
  9. thob

    thob Member

    I got an issue with my battery (6 years old) and most likely with the alternator. Output of the Lucas is 12.8V. What do you think is this sufficient? The books speak of 13.8 - 14.1 afaik.
     
  10. Dave3066

    Dave3066 Active Member

    12.8V is not nearly enough to charge a battery. It should be around 14V. I don't think there's any adjustment available to the charging system so the alternator brushes would be a good place to start.

    Dave
     

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