Something shorted out

[PeaveyBassist]

So I got my new engine in last weekend (1991 m20b25 325i) but needed a radiator. Put a new radiator in today, hooked up the driveshaft, then bolted the exhaust onto the manifolds. Ran the engine again and it ran for a little bit. Although it sounded like the starter wasnt engaged with the flywheel, but it was still spinning or something... After about 5-10 minutes of idle, something made a clicky noise and it sounded like that motor had stopped spinning (what I think was the starter). Then I turned the car off just to double check everything and make sure it was alright. Turned the key back on and the lights on the dash came on but went dim and out real quick. I opened the trunk and there was smoke from the battery so I was afraid I fried the battery, it still holds 12.7v outside the car so I think it is ok but not 100% sure. When the car was running the blower motor switch was on 4 but not working on any speed, then I walked away and came back and it was running again so something is up with that. But then I started checking for shorts to ground. It ends up that the wire going from the power distro block in the engine bay to the fuse block is shorted. I havent found out where, but I know it is shorted somewhere. Is there a common place that goes bad around that area? I tried to pull the fuse box real quick so I took out that 10mm bolt and tried to lift it but it didnt come out right away, what needs to be done to pull it off the body where I can get to wires and stuff? I checked the starter connections and the main power wire to it isnt shorted to ground but the other 3 pins (I have the 4 pin starter) were grounded. Are all 3 of them supposed to be? I assume so but I wanna make sure. Sorry for the long post guys. I have waited forever for this engine to be running again so I cant wait to get the car out. And of course... once it gets running again and what not I will post up pics.

Will

[PeaveyBassist]

Update: I went to Autozone and picked up a Haynes manual because I cant find the Bentley because it has the diagrams I need. Evidently the red wire going to the starter should NOT be grounded. It goes to the alternator B+. That is probably why the battery got over charged or whatever happened to it. Time to go check out the car. It could possibly be the alternator I guess, either that or wiring. But my guess is that it is more likely wiring.

Will

[StereoInstaller1]

Will, if you look under the fusebox, you will see it has a major robber boot going into the car, full of tons of wires. If you want to see what is in there, you can pull the mounting screws for the top of the relay box. Look under the relays to find 3 or 4 phillips screws. You will then be able to pull the box apart.

I was only able to lift the top panel about 3 inches.

It sounds to me like you grounded the main charge wire from the alternator. Replace it with a chunk of 4 guage, so you alternator will be happier. I use a circuit breaker rated somewhat higher than the alternators output.

Luke

[PeaveyBassist]

I had the B+ from the alternator going to the ground post on the starter so the starter motor kept running, although not engaged with the flywheel. The click noise I heard right before turning the engine off was the starter motor dying lol. I tested everything with the multimeter and I think everything else is ok but I need a new starter. We ended up push starting the car though. I have driven 10 miles or so on this new engine and then I parked it. It was idling around 2k or so and sometimes bouncin up an down like the ICV was bad. Also, below 2k or so, if I mashed on the gas it would sorda fall on its face and then pick back up but I think I just need to drive it some more then I will worry about it.

Will

[Mike325]

So that was the problem? Glad you got it fixed. Did any wires get cooked or just the starter? What engine was in there before?

[PeaveyBassist]

It is just a stock rebuild on an m20b25. I THINK the battery is ok and I think everything else is too. I drove it and everything seemed ok.

Will