guysutcliffe
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Hi. My 1979 Series 3 seems to have a dead short. The battery wires glow red hot when connected. Where do I start to try and find the fault? Thanks in advance.
Dead short - glowing battery wires
- Thread starter guysutcliffe
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jamesmartin
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follow the positive battery lead to the solenoid
guysutcliffe
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guysutcliffe
New Member
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I have replaced the burnt out wire to the solenoid and also replaced the solenoid itself. Could it be a short in the starter motor or alternator? I am going to try replacing all wires before I use my get out jail free card and call out the yellow taxi to a garage.
jamesmartin
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petrol or diesel, and yes it could , unplugging alt would prove alt fault or not same with starter
guysutcliffe
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guysutcliffe
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Petrol. I will try with the alternator, then try the starter motor. At 40 years old I am guessing starter motor. I had the alternator replaced a couple of years ago so am hoping that is all ok. Cheers.
jamesmartin
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with replacement parts nowadays a year is often too long ,but starters a good place to start as if main leads getting hot it has to be main lead fed, alt feed would have burnt out
rob1miles
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There's not many places in the harness that can short enough current for that so it has to be near the battery. The alternator would go up in smoke so my money is on the starter or solneoid too.
Bobsticle
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Can you not run it through the cab. It might be better than the heater. 
Colthebrummie
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The solenoid isolates the power to the starter until you turn the ignition key to the start position, so I would have thought a new solenoid would rule out the starter. Does it actually start when you turn the key?
Col
Col
guysutcliffe
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As soon as the battery wires are connected they spark and smoke. The engine does turn over though when the the key is turned. The braided negative wire from the battery was actually white hot! Now replaced, as is the positive wire that was originally cable tied onto the petrol fuel line because that was red hot and melting the plastic insulation. Something somewhere is creating a massive resistance. I will change the positive cable between the solenoid and the starter motor in case that is frayed then might look at the wires from the alternator to the solenoid etc because they look very ropey.
rob1miles
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Something is creating a "very low" resistance. It must be near so I would look for the solenoid shorting tot he starter motor, the cables on wrong, of the startet melted inside. Its pulling 2-300 amps to heat like that so its a decent short. A small one would burn up and stop on its own.
guysutcliffe
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guysutcliffe
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I am going to remove the solenoid to starter motor cable this weekend. It runs behind the engine block so could have frayed over time. If it is showing bare wires, then hopefully the new cable will sort the problem. If it is still insulated, then it must be the 40 year old starter motor that has given up the ghost and is shorting inside. Shame really because for such an old vehicle, it has been remarkably reliable up until now.
rob1miles
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My stater motor end cover melted. The brush holders are steel rivetted to the alloy end cover. These rivets form the lectical connection to the endplate and earth. The alloy/steel join had corroded and was getting very hot but there was no short just so much heat it bent. I changed the end cover and rescued the rest of the starter. From what you say my money is on a frayed lead behind the block. If so then change the earth leads too (or remake the terminals) as the same current that heated the battery cable flowed to earth. If you get a big resistance in the engine earth it has a tendency to fry the speedo cable and speedo guts.
