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Melted positive terminal

Discussion in 'GM 6.5 Diesel Engines' started by Sandyj13, May 13, 2018.

  1. Sandyj13

    Sandyj13 New Member

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    May 13, 2018
    Seattle wa
    Hey I had the positive terminal connector wire melt when I replaced it yesterday. 93 gmc 3500 diesel dually. Replaced both batteries. Happened after running it for twenty ish minutes shutting it off and trying to restart and hour later. Rig never moved.
     

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  2. ak diesel driver

    ak diesel driver 6.5 driver

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    Looks like a pretty high amp short! Possible starter issues?
     
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  3. Will L.

    Will L. Well-Known Member

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    I ruined a couple batteries that way, one from a starter that the solenoid stuck on. Engine cranked until the post bolt melted out.

    Check the starter as AK mentioned, and since you wont be able to use that battery side post again- do yourself a favor and get top post batteries and cables.

    They can handle sustained loads and don’t self destruct or loosen from vibration or weight of battery cables pulling down on them.

    That is how my other battery melted out like that. Simple loose connection.
     
    WarWagon likes this.
  4. ak diesel driver

    ak diesel driver 6.5 driver

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    I guess it could also be considered a fusible link. LOL
     
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  5. Will L.

    Will L. Well-Known Member

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    Yeah an expensive one!
     
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  6. Will L.

    Will L. Well-Known Member

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    I like how in the one picture you can see the bolt was so hot it almost melted through the battery case and let out the acid.
     
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  7. MrMarty51

    MrMarty51 Well-Known Member

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  8. Sandyj13

    Sandyj13 New Member

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    May 13, 2018
    Seattle wa
    Thanks all. Yeah it was pretty impressive in a bad way. So quick newbie question- should / can I test the starter before buying a new battery? Or do I start by popping a new battery in? My son and I double checked the connections and they seemed tight. We did lose the bolt that holds the clip securing the battery in though but hadn’t driven anywhere it just idled.
     
  9. MrMarty51

    MrMarty51 Well-Known Member

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    Pull the starter to get it tested. I would not want to risk another battery for what it takes to remove the starter.
    Then, the starter can be bench tested and if a dead short is experienced, battery can instantly be disconnected.
    Be sure to check the positive cables too.
    surprising that the battery did not explode.
     
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  10. Will L.

    Will L. Well-Known Member

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    You could hook up jumper cables inbetween the new batteries and battery cable to the starter- just plan where the arc is going to be if there is a problem. Wear gloves incase the connection gets hot really quick.

    If you can connect jumper cables without an issue, then no need to drop the starter.
     
    MrMarty51 likes this.
  11. WarWagon

    WarWagon Well it hits on 7 of 8...

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    Check the cable all the way to the starter for bad spots. For example the battery tray loves to wear a hole in the + cable.

    Does the starter ever hang in spinning when you release the key? They can randomly do this in some failure modes. A bench test may not have this random problem show up.

    Does the rest of the cable look burnt? IMO you may have had a loose connection at the battery and an arc melted the battery terminal. Yes - switch to top post connections. I tend to blow the battery connection open internally to the side post where the top post tests fine.
     
  12. JMJNet

    JMJNet Recruit

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    Also, check the alternator?
     
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  13. snarl95

    snarl95 Active Member

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    When you put the starter back be sure to install the small bracket.
     
  14. JayTheCPA

    JayTheCPA Well-Known Member

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    And if there is no bracket, get one.
     
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  15. Husker6.5

    Husker6.5 135' diagonal 16:9HD, 25KW sound!

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    Just looking at those pictures, I'm going to venture that the lead crush washer that goes between the two Positive cable ends was your culprit. Once it has been used a couple of times, it becomes useless because it has flattened out so much that the terminal bolt shoulder now bottoms out on the battery without providing enough clamping force to make a good physical or electrical connection. The bolt may be tight as all hell, but it's not really doing anything. That poor connection causes resistance and resistance plus voltage causes heat. Pull enough load, like 1000 amps through that poor, high resistance connection and you will get heat, LOTS of heat. And melted insulation, lead terminals, battery cases, etc.
     
    Last edited: May 18, 2018 at 4:31 AM
  16. Will L.

    Will L. Well-Known Member

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    I think @Husker6.5 is possibly right. POSSIBLY. One more reason to outlaw stupid a$$ design of sidepost bateries.

    Latest victim I worked on helping a friend:
     

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    Last edited: May 18, 2018 at 11:20 AM
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  17. Will L.

    Will L. Well-Known Member

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    Some taken after trying to clean obviously.
    Notice the green interstate batteries. Guy not afraid to buy top quality stuff. Regularly pays over $100/ hour shop time for repairs.

    Lets zoom in on my favorite part:
    9F885651-1743-4D1B-8111-5CEA65F791F9.jpeg

    If this guy didn’t have perfect cables and a nearly new starter, guess what would have happened before the middle of summer...
     

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  18. schiker

    schiker Well-Known Member

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    The side post mod of using a stud and nut to build a faux post to attach the side terminals is pretty easy and gets rid of the spacer if you cut off all the insulation of the wire and flatten the terminals if you don't have time to mod for top post.

    The side post crappy bolt and spacer on the passenger side loosened and killed an alternator on me. You can sometimes be alerted to the loose connection as low voltage on the dash gauge.
     
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  19. Will L.

    Will L. Well-Known Member

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    Yes that is about the best bandaid for the problem. But it’s like a bandaid for a gash to the bone imo. Do it until a man can afford normal batteries and a couple battery cable ends. Then a few paychecks later get a couple new battery cables that aren’t as small as gasoline engine starters.

    8.0:1 compression vs 21:1 compression. Much stronger and faster starter needs to pull more amps- thats why 2 batteries instead of 1.

    GM as much of a chevy guy as I am, GM is a cheapskate build in the electrical, block casting, any other ways. They made too small of cables, and use inferior connections and batteries to save money.

    Don’t long term bandaid a money savings decision GM went with at your own expense long term just because its what the bean counters went with originally.
     
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  20. Husker6.5

    Husker6.5 135' diagonal 16:9HD, 25KW sound!

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    My mechanic USED to be an Interstate dealer (for direct install into customers' vehicles, not storefront sales) from back in the very beginning, until a little over a year ago when he dropped them due to quality control issues. He started getting problems with cases cracking, side terminal issues and internal problems with opens happening between cells and with terminal leads inside of batteries.
     
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