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Why does ground cable get hot?

Discussion in 'The Hokey Ass Message Board' started by 41 C28, May 23, 2011.

  1. metlmunchr
    Joined: Jan 16, 2010
    Posts: 742

    metlmunchr
    Member

    The only thing muddying the waters is idiotic statements claiming batteries are intentionally mismarked.

    Nice to see someone else wanting to jump in and prove he don't know shit about DC power either. Dumbass.

    Since you're such a 'lectric genius, how about posting something from a battery manufacturer where they say they intentionally mismark the terminals on their products. Ain't gonna happen because they don't do it.

    No, that's not what you originally posted. Mr 38 is on the right track with checking the ground path. You barely touched on the ground question and then started blathering about

    A bad solenoid on a Chevy starter isn't going to make anything get hot. If the solenoid pulls in, that says the coil section is good. If the contact section is bad, there's going to be an open circuit between the cable stud and the starter stud on the solenoid. No path. No load. No heating.

    The only path thru the contact end of a Delco type solenoid is thru the starter brushes and to the armature. Heating of the ground cable says the current is getting thru the solenoid and to the armature. A bad ground can create a high enough resistance to limit the current to an amount that's not sufficient to make the starter turn, but still sufficient to warm up the ground cable.

    If the ground path is good, and the positive cable from the battery to the solenoid is good, the next most likely culprit is the armature dragging on the field coils due to a worn out bushing in the nose of the starter. That's a real common problem with Delco starters from the ones you can hold in your hand to the hundred pound ones used to start large diesels.

    If you remove the starter, check for slop in the shaft at the nose. Lots of times a starter with a worn bushing won't drag when its out of the vehicle because the armature will self-center well enough to run. But, when its back on the engine, the load on the drive pinion will push it tight against the worn bushing and cause it to drag. As you might expect, the wear in the nose bushing will most always be directly opposite the contact line between the pinion and the ring gear. More than a few have been fixed when no parts are handy by driving the bushing out, turning it 180 degrees and reinstalling it to take advantage of an area that's not worn. Not a permanent fix, but it beats walking.

    Both of you geniuses musta skipped school the day they covered Delco starters and solenoids.
     
  2. RichG
    Joined: Dec 8, 2008
    Posts: 3,917

    RichG
    Member

    Metlmuncher, I wasn't rude to you so I'm not sure why you feel the need to be an asshole, but if that's how you deal with shit, good for you.

    EDIT: By the way, it's not a "conspiracy" that batteries are mislabeled, it's called "conventional current flow". Send me your address and I'll mail you a textbook, free of charge. I only brought it up because someone previously in the thread had mistakenly mixed electron flow theory with conventional flow theory and had made some mistaken assumptions about how to go about troubleshooting.
     
    Last edited: May 24, 2011
  3. tommy
    Joined: Mar 3, 2001
    Posts: 14,758

    tommy
    Member Emeritus

    I had the same problem 40 years ago. I ran the ground cable from my battery under the seat to a welded lug on the frame. The truck started fine until it got warm. Then the dreaded click click click. Everyone thought it was heat soak. It was not. I moved the ground cable from the lug to a bolt in the trans case and the hot start problem was solved.

    It sounds to me like the heavy current needed to start the car is going through the body ground strap (usually smaller than a battery cable) causing it to heat up. If you check the factory battery cable ground locations on cars from the 40s on up you will find that they all go directly to the engine block to carry the heavy amps of starting.


    Yes people get away with heavy jumpers from the frame to the block but each mechanical connection in the starting circuit is a potential spot for corrosion and a poor connection. Often it takes a few years for the additional resistance at the many connections to accumulate to the point of the clicking syndrome.

    I have seen some late model cars with the batteries mounted in weird places with all kinds of connections to get to the starter. I thought to myself those will keep the techs busy in a few years because you have to clean every single one in the circuit to make sure you have got it.


    Top post batteries would work fine for years and then the click...a quick battery post cleaning solved the problem. You could not tell that it was a problem by looking at it. After all it worked fine for years and was never disturbed. It can take years for this to happen. The side post invention helped but they can still corrode and need cleaning.
     
    Last edited: May 24, 2011
  4. Bigchuck
    Joined: Oct 23, 2007
    Posts: 1,139

    Bigchuck
    Member
    from Austin, TX

    Had OT vehicle in for repair that had starting issures. The main ground cable from the battery had come off the engine and all the ground was going through a 16ga (or so) wire that was connected to another circuit. All the insulation was burned off and the wire was nicely toasted. How it worked for any period of time is a big mystery to me.
    The customer said he had been having trouble for a while.
     
  5. evs1
    Joined: Oct 3, 2010
    Posts: 160

    evs1
    Member

    If you have a conductor that is getting hot then check the connection at the first point where it is not hot. That is where it is meeting high resistance and creating heat instead of transferring current.
     
  6. Ned Ludd
    Joined: May 15, 2009
    Posts: 4,035

    Ned Ludd
    Member

    metlmunchr and RichG, you're arguing terminology. From Wikipedia:

    "A flow of positive charges gives the same electric current as a flow of negative charges in the opposite direction. Since current can be the flow of either positive or negative charges, or both, a convention for the direction of current which is independent of the type of charge carriers is needed. Therefore the direction of conventional current is defined to be the direction of the flow of positive charges. In metals, which make up the wires and other conductors in most electrical circuits, the positive charges are immobile, and only the negatively charged electrons flow. Because the electron carries negative charge, the electron motion in a metal conductor is in the direction opposite to that of conventional (or electric) current."

    So battery terminals aren't marked unusually. Electron flow might be from negative to positive, but seeing the current in the opposite direction is a perfectly useful and practical fiction which enables one to deal with electrical problems effectively. What we're doing is understanding the flow in terms of equivalency to a flow of positive charges.
     
  7. kenymac
    Joined: May 8, 2008
    Posts: 40

    kenymac
    Member

    Metlmunchr, Is Right on about checking the bushings in the starter!! That is a very common problem. Also worn brushes will also do the same thing as delco starters will work great cold untill they get hot then the dreaded click or slow to turn. I have seen them wear the brushes clear down to the holders and still work. But still check for bad connections.
     
  8. RichG
    Joined: Dec 8, 2008
    Posts: 3,917

    RichG
    Member

    All I originally attempted to do was correct someone who had posted that the current of the battery flowed from the "negative" terminal, which it does not.

    In a mistaken attempt to simplify my explanation metlmuncher became offended and you know the rest.

    The current (amps) in your car flow from positive to negative. The positive post is the "hot" side.

    My apologies to the OP for muddying up his thread.
     
  9. 1971BB427
    Joined: Mar 6, 2010
    Posts: 5,722

    1971BB427
    Member
    from Oregon

    Make sure your main ground cable from the battery goes directly to the engine first. Then you can go from engine to frame and body with small ground straps, as the rest doesn't require as large a ground.
     
  10. Ratrod37
    Joined: Apr 12, 2007
    Posts: 276

    Ratrod37
    Member

    Wow alot of people like to show off there education,electron flow..etc. How did the problem start? Did it work before,is it a new build and this is your first try at starting it or was this a working car that just developed a new problem.Figure out what is wrong before you start changing parts.Make sure it's the correct starter and that it works.All small block Chevy starters are not the same. Slow down and start with the easy stuff first before you start studying electron flow and manufacturers mislabeling.The small block chevy starter system is one of the most basic you will find.
     
  11. 41 C28
    Joined: Dec 17, 2005
    Posts: 1,770

    41 C28
    Member

    Thanks again to everyone for all the knowledge and suggestions. I didn't work on it today but I'm going to tomorrow. IF.... I don't do any good with the sbc I do have a hemi sitting in the garage and that would be a good excuse wouldn't it. I 'll post my findings on the starting issue.
     
  12. 41 C28
    Joined: Dec 17, 2005
    Posts: 1,770

    41 C28
    Member


    All fixed.

    I replaced the 4 gauge ground cable with a 2 gauge cable directly to the engine block.
    $18.99 from Auto Zone and its made in the U.S.A.
    She just about starts now with the key still in my pocket.
     
  13. RichG
    Joined: Dec 8, 2008
    Posts: 3,917

    RichG
    Member

    Awesome! I'm glad to hear you got it worked out.
     
  14. tommy
    Joined: Mar 3, 2001
    Posts: 14,758

    tommy
    Member Emeritus

    Thanks for the follow up. Other people that read this will learn also and not need to start a new thread on a common problem.
     
  15. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,162

    Atwater Mike
    ALLIANCE MEMBER

    When I had my shop, this was the most common "home built hot rod problem".
    It was also the easiest to diagnose and repair.
    (volt meter at progressive points starting with battery posts under load is the most direct method)
    Also should have checked ampere draw...200 amps starter draw?
     
  16. Jethro
    Joined: Mar 5, 2001
    Posts: 1,490

    Jethro
    ALLIANCE MEMBER

    Another ground that is often overlooked and causes a lot of grief is the little ground strap that goes from the block to the firewall....mostly Gm's I think.....Usually after a motor swap the radio acts funny then the dash lights and gauges work intermittently because the body is grounding through the motor mounts and when the engine torques the ground comes and goes......very frustrating to be sure!
     
  17. Ratrod37
    Joined: Apr 12, 2007
    Posts: 276

    Ratrod37
    Member

    That was too easy. I think you should take it all apart and try to find something more complicated. Just kidding,glad you got it fixed.
     
  18. AllenK
    Joined: Dec 12, 2010
    Posts: 220

    AllenK
    Member

    I have aluminum heads on the SBC in my '64 C10. From the factory the negative battery cable attached to a bolt hole in the head,and it has a ground that attaches to the core support. I still have my neg. cable attached to the head even though it's aluminum. Can I attach it to the frame or somewhere else? I know aluminum is not as good as steel when it comes to electrical conductivity.
     
  19. RichG
    Joined: Dec 8, 2008
    Posts: 3,917

    RichG
    Member

    Aluminum conducts electricity just fine, the only concern I would have is where the steel headbolts go through the heads into the block, running electricity through those could cause some corrosion, especially around the water jackets. Personally, I'd move the ground connect to a bell housing bolt or somewhere substantial and closer to the starter (On my straight sixes that I've had, I've always ran the ground cable to the side cover). That keeps your ground close to the biggest electrical draw in the car and makes it more efficient (I think that's been mentioned already in the thread).
     
  20. AllenK
    Joined: Dec 12, 2010
    Posts: 220

    AllenK
    Member

    Thanks for the help! I've had two sets of alum. heads,and I bolted the neg. cable into one of the accessory holes on the front of the passenger side head. That water jacket corrosion comment is very interesting because I just had a head crack around the water jackets. All the coolant went right out the exhaust. We figured the CNC machine might've been out of whack a little or there just wasn't enough metal there. Maybe it's what you suggested? The bellhousing was what I was thinking as well on where to bolt the cable.
     
  21. RichG
    Joined: Dec 8, 2008
    Posts: 3,917

    RichG
    Member

    I kinda doubt you'd see enough corrosion to crack the head, unless we're talking about something that's been together for quite a while. Maybe... but doubtful. What I've seen industrially is bolts that corrode, break off, and you end up having to ream the whole thing out to helicoil repair it.
     
  22. AllenK
    Joined: Dec 12, 2010
    Posts: 220

    AllenK
    Member

    I don't think that's what caused my problem either,but anything can happen to me!
     
  23. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    Member
    from Wisconsin

    I've seen this problem many times. Some people don't think that the ground needs to be as big as the positive cable. Electricity flows through a circuit and all parts of that circuit have to handle the same flow. The ground cable has to be just as big as the positive cable to accommodate flow.
     
  24. henrys_way
    Joined: Oct 5, 2006
    Posts: 216

    henrys_way
    Member
    from Maine

    I thought this was a good read... Some very smart people on here. I have had electrical problems in the past that ended up being a simple Ground Issue.
     

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