What goes bad in a starter that causes it to lock up?

Discussion in 'Gen 1 & 2 - Engine, Exhaust, Drive Line & AC syste' started by Jr's Sho, Apr 15, 2004.

  1. Jr's Sho

    Jr's Sho SHO Member

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    Today I had to replace my Ford reman. starter with a fresh one. Reason I ask is because I have two starters that I would like to take parts off of one to fix the other starter. The one I just pulled off my car that I want to fix would occasionally lockup when cranking, requiring a bang from my hammer. It would also make a grinding noise sometimes on start-up. Other times, it would start just fine. Are these syptoms of bad brushes, armature? I'm not too familiar with starters but I have both apart right now. What should I look for? Thanks.
     
  2. Mr Anonymous

    Mr Anonymous Tire Wall Staff Member

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    On the PMGR starters used in the Gen II & III SHOs, the only items that really fail are the brushes or the solenoids. The magnet housing, armature, and planetaries almost never fail. You'll occasionally see a starter drive fail, but mainly it's caused by worn out brushes.
     
  3. SonicRiot

    SonicRiot Handbanana!

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    Would the starter actually lock up, or would it just not turn? Would you hear a click and then nothing? Grindning? Winding? If it just clicks and nothing happens, the pull-in and hold-in windings are most likely fine, so the solenoids are eliminated as a problem.
    Look for broken or missing teeth on the planetary gears themselves...look for physical damage. If there isn't any, you can use a DVOM to test the field windings and armature for shorts. Inspect the brushes and commutator. If the problem was intermitten, it was most likely shorting out somewhere and the armature would not spin.

    If you'd like, I can copy my lab assignments from Auto Electronics class and give them to you with acceptable values for resistances and such so you can test the starters for shorts. I learned more than I thought the first time I ripped into a starter.

    My starter went bad before the winter...I was told that I had a "dead spot" :squint: because the starter would spin up and not turn over the motor and it was an intermitten problem. Now I know why it really wasn't working. The hold-in winding was bad...the solenoid in other words. The starter would spin up without contacting the flywheel first. Now....why couldn't the tech tell me that? What is so hard about taking apart a starter and learning how it works?!?!

    So let me know if you want those labs. I love taking crap apart just to see what it looks like on the inside! :cool:
     
  4. Jr's Sho

    Jr's Sho SHO Member

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    Thanks for the offer but I'll pass on the labs. It looks like the brushes are really small on the starter that I replaced today. I'm going to swap brushes and clean it up and put it back together. thanks for the replies.
     
  5. jelloslug

    jelloslug Digital

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    Having to hit the started with a hammer is a sign that the brushes are worn out or very badly gummed up. Using this technique on older starters (with would fields) is OK but it is a VERY bad idea on newer permanent magnet style starters. You can dislodge the magnets by striking the side of the starter motor, which will ruin the starter. Things that can lock up a starter motor are dislodged magnets, seized bearings, failed brushes, failed armature, foreign material between the armature and the magnets, or failure in the wiring to the brushes. After you take the starter apart you may want to take the armature to an alternater/starter rebuilder an have them test the armature for shorts or grounds (I would do it for you at my plant if you were close enough).
     

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