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Thread: starter motor experts 72 400 smal block

  1. #1

    starter motor experts 72 400 smal block

    For the first time in 18 years truck would not start. Tapped the starter with a hammer and started instantly as it always does. Worked fine for a day then today didnt so did the tap routine and no luck.

    Took the starter motor out which is not easy with headers but too hard to drop they exhaust for a few reasons. Ive run 12 volt to the motor and it works fine. I hooked up lamp cord to the solenoid and listened for a click. Should the solenoid not jump forward with a wire to the "S" small terminal. I cant jumper the big to small terminal with a screwdriver as the headers are in the way, Hell I can barely even see the starter motor.

    ILl go try the wire to the solenoid one more time to see if I can hear a clilc of the gear snapping in and out but dont think so and pretty sure with 12 volts to it should do that on its own.

    thanks

    w

  2. #2
    Join Date
    May 2018
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    Lancaster, Ohio
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    time for a new solenoid
    IF YOU CAN FIND A GOOD REBUILD SHOP have the starter gone over GOOD LUCK finding one
    would not replace the starter as the rebuilt or new one will probably be worse then the one you got
    Ron

  3. #3
    thanks nok clilcking with 12 volts to that small terminal, Told the other terminal is for points and this one has electronic on it. Do have an awesome old school rebuilder in a small down close by. He did my alternator in the 92 roadmaster. Cheap and excellent work, hope he still owns the business ill be calling monday morning but needed the truck today. Thanks on the not rebuilt, I even made sure I kept the same alternator for the roadmaster wagon. Love the old school guys, have a transmission shop like that but know time comes and the businesses get sold.

  4. #4
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    We have some really good starter, and alternator rebuilders here, both very old school, too. I had one rebuilt for a 1979 tractor, while I waited.

    Can you replace the solenoid without taking a header off? If you can't jump it, I'm expecting not. I have replaced a hard to get to one with a swivel socket. It had to be a swivel socket though, as there was not room for a swivel adapter.

    There are some good, new starters though. Don't buy one from an auto parts store.

  5. #5
    I looked at the solenoid and didnt see how its removed. I have another starter from a 70 350 but it is different mounting system. Ill go the old school guy tomorrow and hope its still him that owns the bus as past experiences were excellent. I want this one rebuilt, ive had it 18 years and first issue, truck is 49 years old.

    Friend uses the gear ones and said easy to start on high performance motors. This truck barely turned over more like started as you turned the key so no need for more than what was in it.

    As far as jumping I didnt go the solenoid battery cable but rather from the battery to the small hook up on the solenoid and heard nothing. Not sure if that is right but pretty sure that shows the solenoid is not working. Will show up with it tomorrow morning.

    thanks

    w

  6. #6
    Join Date
    Jan 2004
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    I don't if it works on other cars but on Chevys from the '50-'60s, the main lug on the starter solenoid was held tight to the case by a large nut. One could disconnect the battery for safety, remove the large wire from the solenoid, loosen the nut, turn the shaft of the lug 180 and retighten the nut. The starter solenoid would work normally for a long time after that. The lug has a flat head on the inside of the case. Overtime the current flow through it would pit the mating surface inside the case. Loosening the nut, rotating it and then retightening the nut put a new surface under the spring loaded contact. I watched my father do it on his Olds and Pontiacs and I did it on the starter on my '56 Chevy.
    Ken

  7. #7
    thats interesting but truck is a 72 so would it still work then? will save that bit of info as never heard it before

  8. #8
    Join Date
    Sep 2016
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    It is possible the main cable is bad so there is no 12 volts jumping to the solenoid.
    A gear drive unit might be easier to fit in there? I would never use a hammer to hit a starter use a dry 2x4 or wood bat. Something that is not electrically conductive.
    Bill D

  9. #9
    This is the starter that was attached to the 8.1L engine in our boat-- not hardly a '72 SBC but most GM starters are pretty similar..
    cstrtr.jpg
    One day the boat wouldn't start, this was why

    Here's a random pic of an older GM starter that doesn't have the flat-edge mount--
    chvtrtr.jpg
    --you mention you didn't see how the solenoid is removed- both of these solenoids, like most, are held to the starter with a couple of small bolts on the gear end...
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  10. #10
    Bill 12 volts to the starter and it jumped and ran fine

    12 volts from the battery right to the small termial and nothing, I think the solenoid should have fired and I would have heard it

    Hammer was a finishing hammer and I was tapping, Did it a day or two before and it started instantly

    Kev do see how it comes out, long day cold on my back no room to move covered in grease and my Lee Valley VR3 headlight had pooped out so for the first time had crappy lighting when used to the headlamp. Do see a fine crack in the solenoid cover as well.

    Ken is that the kind of bolt you are talking about that can be rotated or different, that to me if so would have to pushed in then rotated and pulled back if so.

    thanks

    w

  11. #11
    Ken you were right on the rotate thing, I asked and he said yes it went to about 1980., He said on mine its a rectangle so you do a full rotation. i could have done that but want it rebuilt, he saw the crack in the cover on the solenoid and that has to be replaced. Just wanted to mention the rotate thing as no one else has so thanks on that bit of info.

    w

  12. #12
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    FYI- a starter may appear to turn over just fine by itself, but it may not do so under load.

  13. #13
    Join Date
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    Quote Originally Posted by Warren Lake View Post
    Bill 12 volts to the starter and it jumped and ran fine

    12 volts from the battery right to the small termial and nothing, I think the solenoid should have fired and I would have heard it

    Hammer was a finishing hammer and I was tapping, Did it a day or two before and it started instantly

    Kev do see how it comes out, long day cold on my back no room to move covered in grease and my Lee Valley VR3 headlight had pooped out so for the first time had crappy lighting when used to the headlamp. Do see a fine crack in the solenoid cover as well.

    Ken is that the kind of bolt you are talking about that can be rotated or different, that to me if so would have to pushed in then rotated and pulled back if so.

    thanks

    w
    Yes. It's the bolt-like device where the main 12 cable attaches.
    Ken

  14. #14
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    Quote Originally Posted by Warren Lake View Post
    Ken you were right on the rotate thing, I asked and he said yes it went to about 1980., He said on mine its a rectangle so you do a full rotation. i could have done that but want it rebuilt, he saw the crack in the cover on the solenoid and that has to be replaced. Just wanted to mention the rotate thing as no one else has so thanks on that bit of info.

    w
    Nice to know that it would work until 1980 or so!
    Ken

  15. #15
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    I was aware of the loosen and rotate method Ken alluded to. Your trouble shooting was spot on Warren. If jumpering to the pull in terminal on the solenoid gets no result then you've isolated the problem. Hopefully it's rebuilt and back in service now. I have a handy little tool called a Power Probe that is great for things like this. It tells you the voltage that is present and you can use it to energize circuits as well.

    amazon.com/Power-Probe-III-Automotive-Diagnostic/dp/B08YS492J4/ref=sr_1_9?dchild=1&keywords=power+probe&qid=16210 96213&sr=8-9

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