Battery Sparked then Smoked

[duckBoy]

Hey

I recently just swapped out my motor and when it came time to connect the battery, it took a crap.

First I connected the ground and then when I connected the positive terminal, it sparked and then there was some smoke that came from the terminal.

I was wondering would another battery fix this? Obviously there some wiring issue, but I never touched anything.

Any advice

[pegase747]

I think a new battery will not fix anything.
I think you have a big short somewhere.
Is you battery in the trunk or engine compartment ??

In both case, you should check you positive lead for any grounding, do an insulation/resistance check using a meter.

You can try to disconnect the positive terminal in the engine compartment and connect your battery again, carrefully and ready to disconect it quickly...


Cheers
Pierre

[AndrewBird]

How much did it smoke?

[duckBoy]

It smoked a lot from the alternator connectors, mainly the thicker one.

My battery is in the trunk.
Where is the positive terminal in the engine compartment?
I have a basic multimeter that can measure resistance.

[nando]

you definitely hooked something up wrong, either at the starter or the alternator.

positive terminal is on the passenger side bulkhead above the front battery tray.

[duckBoy]

Yeah, i never disconnected the starter wires only the alternator.
Is there an inline fuse that I could check between them? Would i be wise to through in a fuse on the positive battery terminal to help prevent this when testing it out again?

[nando]

I think that function is handled by the fuseable link?

[duckBoy]

I heard about this fuseable link, but where the heck is it located at? I cant find any picks

[pegase747]

I think you did connect something wrongly on the laternator, and the + is somewhat grounded. Disconnect the thicker wire on the alt and try connecting your bat again.

Pierre

[duckBoy]

I'm going to pick up another alternator later this week.

My plan is to remove the complete intake manifold to see how far back the wire got burned. Once I figure that out I'll connect the other alternator leaving the thicker wire un plugged and finally connect the battery.

If that works then I'll connect the alternator back up and gentle rub the positive terminal to the batter.

[duckBoy]

I checked out the harness and it burned all the way up to the T junction, where the battery wire meets the alternator and starter. All the other wires look fine they just have melted plastic on it.

I wanted to know, since i put polyurethane motor mounts from "silence" could that not be grounding the engine to the chassis properly?

[bmwman91]

The engine is grounded to the chassis by a large cable on the passenger side (or at least it is supposed to be).

The fusible link is in the trunk, on the smaller of the two wires coming off of the + terminal of the battery. You have to remove the hard plastic cover on the cable to get at it. The larger wire (~15mm diameter) is un-fused.

It sounds like you got some of the power wires mixed up on the alternator. Be very careful, and find the wiring diagrams for the car. If the insulation is melted off, you must replace all of the damaged wires. If you are lucky you won't have to replace the entire +12V cable assembly (which is a BITCH).

[duckBoy]

The alternator was the culprit. I cut the existing alternator wire up till the T junction in the wiring harness. Then I binded new 4awg wire to T connector. Replaced the alternator with a new one and make a new ground wire for that.

Car runs fine, but now the oil light came on, now im not sure if that wire got cooked even though it looked fine or the oil switch is bad.