Hello! My 1986 240 keeps shorting out alternators and I cannot figure out why. I just installed the third one. (since they are under warrenty, the parts store trades them in for a new one) Before installing, I made sure all wires were tight. After installing, I turned the key to the accessories mode. The light came with the other dash lights on as it should. I started the car and the light turned off just as it should and my oem volts guage read a very healthy reading. After about 8 seconds, though, the guage started going haywire. The needle would drop down to the red zone (12v) then jump back up a bit; then it would jump back up to its previous 'fully charged' location. I also noticed that the dome light was flickering. The car was running normally the whole time as well. Is this a grounding problem? I had a hard time attaching the ground wire (somebody had shaved off the screws holding the two parts of the alternator together). Would it help to attach the ground wire to one of the positive terminals?

Thank you!

 

Very bad things will happen if you do that. See the attached picture to verify your connections.

 

That's a great diagram!
According to it, all of my connections are good. Like I said, somebody shaved off the posts which held together the two pieces, so I just have a little nub to hook my ground to, but it does make contact for sure. Could that still be the problem?