1996 240sx : alternator output intermitten

[matt4pl]

a little background:

i've killed 3 alternators during this spring/summer, 2 due to oil, one due to a crapped out battery, or so i think, it was tested and both were bad so i repalced both (under warranty )

i have an optima red top

so about two weeks ago i noticed that sometimes my car would run crappy, wouldn't accelerate very well, felt like it was bogging/choking, the dummy lights would come on when coming to a stop, along with the RPM's dropping to a near stall. at night the lights would get dim. other times it would run just perfect. this is also regardless of what the sound system was doing. most recently when it happened i noticed the lights were much dimmer then usual so when i got to my friends house we checked the volatege, with the car off the battery read11.9, wiht it on it read 11.6 for batt and alternator. i also noticed a faint whirring/whinning sound when it ran crappy. i checked the positive cable running to the alternator and it looked ok, i could see some of the copper. i plan on repalcing this when i do whatever work is neccessary to fix the car anyway. i checked the tension on the belt and it seems fine, im not too sure on how much play should be in the belts. i did notice that the long tensioner bolt was almost 2 inches out and totally lose but the bolt that holds the tensioner bolt the the alternator and to the tensioner bracket was very tight and i could not more the alternator around by hand. i'm sort at a loss here so i dunno what the next thing i should check is. i didn't get to see much cause it was night out. any ideas or help would be greatly appreciated

[NISTECH]

Sounds like you got another bogus alternator. Rip it out and have it tested.

[s13sr20chris]

theese are not advance or auto zone alternators are they? those things are junk.

[matt4pl]

rebuilt lee auto parts alternators... i had no time but im taking it in today

[matt4pl]

alternator is fine. stuff was sparkin all over when i was pulling it out, front the positive alternator cable... i dunno if thats normal cause it never happened before but then i think my batt was usually dead

[NISTECH]

umm yea your suppose to disconnect the negetive battery cable when ever you do an alternator or starter.

[matt4pl]

yea i figured as much, afterwards, but i didn't have the right tools anyways, most were at my friends place still after a transmission job, so any ideas where i should be looking at now?

[matt4pl]

we looked at it, heres what we found... the loop conector for the stock ground was very lose, it came off when we tried to bolt it back up

i have a grounding kit and had a 2nd wire going to the negative from the alternator. now according to the diagram the negative on the alt goes to the a chassis ground or the battery negative so i'm not sure if both were somehow lose or is there something i'm missing?

[matt4pl]

ok so after we put it all back we started the car. before starting it batt had 11.66 volts, it started dropping off slowly once the car was on. belt is on tight, ditto for power cable and ground wire (going directly to batt), engine was idling at 1500 rpm at 1st, warm up cycle or w/e. alternator voltage matched battery voltage. i am totally clueless where to go from here. i had the alternator tested and they said it works fine

i had nothing running but the motor when i tested this

[NISTECH]

With the car running check for power at both terminals in the connector and a power at the large hot on the alt. If the connector has no power on either side check all the fuses in the car and under the hood.

[matt4pl]

well found the problem, or so i believe. i bolted everything back up before i checked the plug. it was putting out 14.4 at the alt and batt. i took it for a test drive, only ot find out the problem presisted. so then when we pulled into a lot my frined jiggled the plug and was moving the wires around, which caused the voltage to go up when he pushed em into the plug, so im almost positive its the plug

[matt4pl]

checked the voltage on the plug before i put in a new one, it read batt voltage, same with after the new plug, i noticed that the insulation was cut almost all the way around on the wires at the base of the plug, so i cut it out, put in the new one, shrink wrapped the connections, prolly gonna redo them soon because it'll be easier to get to em from under the car (no garage for now so cant get the car jacked up)

[matt4pl]

no dice

[NISTECH]

Of the 3 which wires do you have power at when the car is running?

[matt4pl]

havent checked that yet, no garage, plug is a PITA to get to, but i got the battery tested, it was bad, replaced it, its putting out 14.3x now with radio on (900W max system, never prolly sees half of that), im gonna try to check the plub tomorrow when its light out (last time i tried messing with it in the dark i lose my whole finer nail)