Problem jumping friends BMW

drew and not u

drew and not u

New Member
Joined
Jun 15, 2006
Location
Chapel Hill
My buddy tried to start his 86 325 and the battery was dead. I pulled up and tried to jump him off, but his cables got really hot (they were dinky) and it sparked when I connected the ground. It didn't start and I didn't want to leave the cables on there to get any hotter. I tried connecting my beefier cables, but they sparked pretty bad too and began to get warm.

Yes, I quadruple checked for proper connection and looked for obvious shorts. I don't know the first thing about these European vehicles, so any tips would be nice.
 
i know you said you checked, but that sounds a classic case of hooking them up wrong. are you verifying which terminals are which by the symbols on the battery or by the wire color? don't go by the wires, with a vehicle that age it's highly likely some retard put the wrong color cables in the wrong place at some point.

that said, cables will get a little warm, but only when you're putting a load across them (i.e. trying to start the other vehicle). with it just sitting there they shoudn't get hot. also, it's not uncommon to get a little spark when you hook the final connection up. shouldn't be a big one though.

try grounding the negative to the body or other large chunk of metal under the hood vs. hooking it directly to the battery.
 
Thanks bud. I verified the + and - on the battery itself. I figured it was probably just his wimpy cables, but after mine sparked I got paranoid and didn't want to do any damage to my battery or anything. His battery is mounted in the trunk (from the factory) so I guess I should be able to find something decent to ground it on.
 
A lot of times, even when the battery is in the trunk, there are jump terminals under the hood. They are much closer to the starter. Sometimes that can help.
 
That spark and or cables getting hot means one of two things. Hooked up wrong, or severe load.
The severe load may be a dead short on his car, or something major is draining his battery.
Might wanna try pulling his battery out, or at least disconnecting it to charge it, then put it back in.
Not sure, but both of these cars are negative ground, right?
 
X2 on the jump terminals under the hood.
 
e30's have ground problems with some frequency. the negative cable in the trunk sometimes builds rust and corrosion between it and the chassis. the design of the trunk causes a lot of water to pool in the battery tray and the tray on the drivers side if the trunk seal is bad. there are jump terminals under the hood. look on the passenger side of the firewall, there is a wiring bundle running across from the drivers side. you will see a square plastic cover over the positive terminal, its a hex shaped 22mmish sized lug. connect to one of the strut studs for a negative
 
did BMW ever run a Positive ground set up? I had a '65 Mini Cooper that was a Positive ground system.

but I don't know enough about electrical crap to know if that would've been more apparent with other issues if you tried to jump from a Negative ground vehilce
 
mbalbritton said:
did BMW ever run a Positive ground set up? I had a '65 Mini Cooper that was a Positive ground system.

but I don't know enough about electrical crap to know if that would've been more apparent with other issues if you tried to jump from a Negative ground vehilce
Click to expand...
not in the last 35 years or so....
 
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