Slow cranking

Discussion in 'Domestics' started by Friday, Apr 13, 2017.

  1. jd

    jd Hero Member

    Joined:
    Jan 14, 2007
    Messages:
    368
    Likes Received:
    16
    Had slow cranking on our RV. It's a Ford V10 with permanent magnet starter and GP 65 battery. Battery's old and I thought it was a goner. Would crank the engine cold but not hot. Cleaned terminals and put CP or whatever that purple goo is on the cleaned areas. Been cranking Cold and Hot since... So a good cleaning might pay off for you. Also, be aware the cables CAN (but not all that often) corrode inside the "sealed factory" terminals. That's why a Voltage Drop Test is good.

    I don't know where you are, Friday, but here in FL right now I can about start mowing from one end about the time I finish the other end. And we're only on a Quarter Acre!!!
     
    Friday likes this.
  2. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,756
    Likes Received:
    55
    My wife was griping about having to start mowing just before Valentine's Day. I told her I was going to get her a goat for V-day. When the day came but no goat, I explained that it was too hard to wrap... it kept eating the paper!
     
    Friday and Mobile Dan like this.
  3. jd

    jd Hero Member

    Joined:
    Jan 14, 2007
    Messages:
    368
    Likes Received:
    16
    Bill, you're better off than I am. I read your reply aloud and MY wife said "I already have one."
     
  4. Friday

    Friday Hero Member

    Joined:
    Apr 7, 2007
    Messages:
    255
    Likes Received:
    1
    Gender:
    Male
    Location:
    Tecumseh, KS
    LOL!
     
  5. kev2

    kev2 wrench

    Joined:
    Nov 14, 2006
    Messages:
    4,601
    Likes Received:
    35
    Gender:
    Male
    OK - its Monday Friday, :)
    are you still working this -
     
  6. Friday

    Friday Hero Member

    Joined:
    Apr 7, 2007
    Messages:
    255
    Likes Received:
    1
    Gender:
    Male
    Location:
    Tecumseh, KS
    Sorry, forgot I had oncologist appointments on Monday. Tested at the starter today. With key off: Reading at starter is the same as the battery, 12.2V. With key on, drops to 12.0V, while cranking, drops to 6V. When running, reads 14.4 volts.
     
  7. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,756
    Likes Received:
    55
    And the battery stays up near 12V while cranking? That sounds like there is a 6V drop in the cable from the battery to starter when cranking. Verify by reading voltage between the battery + term and the starter term, while cranking. This does not sound like it is a starter issue.
     
  8. Friday

    Friday Hero Member

    Joined:
    Apr 7, 2007
    Messages:
    255
    Likes Received:
    1
    Gender:
    Male
    Location:
    Tecumseh, KS
    Got it. Raining and cold here right now, will have to wait on the next reading. Maybe this afternoon, when it tops 55 degrees.

    upload_2017-4-26_9-19-24.png
     
  9. Friday

    Friday Hero Member

    Joined:
    Apr 7, 2007
    Messages:
    255
    Likes Received:
    1
    Gender:
    Male
    Location:
    Tecumseh, KS
    No. The battery drops to 9.8 when cranking.
     
  10. kev2

    kev2 wrench

    Joined:
    Nov 14, 2006
    Messages:
    4,601
    Likes Received:
    35
    Gender:
    Male
    recent acquired vehicle -
    battery cable < 20$
    Battery @100
    Time spent playing + testing+ and not using the new truck. >> greater than those 2 items
    I would expect to replace some items and these easy. money well spent.
     
    Friday likes this.
  11. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,756
    Likes Received:
    55
    9.8V at battery, dropping to 6V at the starter, still kind of hints at a poor cable/connection. Did you measure the 6V, while cranking, with one meter probe on the starter case for "ground"? Remember, we need to check both the + and - paths from the battery to starter.
     
  12. Friday

    Friday Hero Member

    Joined:
    Apr 7, 2007
    Messages:
    255
    Likes Received:
    1
    Gender:
    Male
    Location:
    Tecumseh, KS
    I tested with one lead (+) on the main battery cable lug (bolt) of the starter and the other (-) on the starter case.
     
  13. Friday

    Friday Hero Member

    Joined:
    Apr 7, 2007
    Messages:
    255
    Likes Received:
    1
    Gender:
    Male
    Location:
    Tecumseh, KS
    Kevin, you are correct. However, now retired on a fixed income. Cable, not so much of a problem. $125 for battery, will need to wait. My medical bills (my part after insurance) average over $3k a year, because of all the testing every 3-4 months. Before retirement, not so much a problem, as I used a HSA to handle these. That's why I am careful to not throw parts at a problem.
     
  14. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,756
    Likes Received:
    55
    Do one more test, check voltage between the battery - term and the starter case, while cranking. This should be near-zero V, as should be the voltage from the battery + to the power-in term on the starter. We need to pin down where that 4V is being lost.
     
  15. Friday

    Friday Hero Member

    Joined:
    Apr 7, 2007
    Messages:
    255
    Likes Received:
    1
    Gender:
    Male
    Location:
    Tecumseh, KS
    Bill, up above you said to "Verify by reading voltage between the battery + term and the starter term, while cranking." Is this a different test than what you are suggesting here, or the same one? It sounds like the same one. Tomorrow I have to accompany my 4 year old granddaughter on a trip to the zoo with her pre-school class. It's from 9:30 till noon. Hopefully I will survive that and can do the test, but there is still rain in the forecast.
     

Share This Page