Battery/altenator problems

[91 240]

This is for my 91 240 in which i've just replaced my blown SR. All that was done was to pull and drop the motors and to clean up the lower harness(new looming, new elec. tape, etc)Since then I've gotten a 1000 mile used SOHC altenator that work for a day then quit. Got it tested and was only pulling 3 volts. Got the battery charged again (4th time) and bought a brand new altenator. It ran good for about 10 miles. I took it to a parts store to check it out to make sure. They brought out their portable battery/altenator/starter diagnostic machine and hooked it up to the battery and the altenator was not charging, 3 amps at idle and 20-30 amps at 2000rpm when it should be 80amps. I pulled the alt. off and had them bench test it, it was charging at 13-14v. Put the alt. back on the car and drove for another 5 miles when the damn thing died again. The fusable link is fine, the 75 amp fuse is fine, wiring seems fine.

Any suggestions???Thanks

Avery

[NismoRb20S13]

change the belt and see if that helps .. also make sure it isnt too tight or too loose they dont like that.