is my alternator screwd?

[PSYKO PHOENIX]

hey guys, hope you can help, ive been having some problems with an oil temp gauge going mental and jumping around when the car uses and extra electricity, eg, bass, head lights, indicators etc etc the gauge is getting replaced eirly next week but i want to make sure its not my altinator or other wiring things...

i dont know if this is related or not but ill type it any way it may be usefull, there is a whine from my stereo it gets worse when my headlights are on and even worse with the high beams are on, the gauge is similar in the sence that high beams cause the worst jump

about 5 mins ago i took some voltage readings at the left headlight after a drive here are the readings

headlights on - 13.0 - 13.06 (the other day when i tested the car cold this was 13.48)
high beams - 11.78
headlights on with indicator - 12.97
high beams and indicator - 11.70
headlights and cooling fan - 12.83
high beam and fan - 11.48

is this normal or is there somthing wrong with the alternator or wiring etc??

cheers looking forward to getting to the bottom of it!!:bang:

 

[tt460]

Seems a bit on the low side, could just be a bad or dirty connection or earth, i would start by checking all connections and earths and checking the tension of the belt as it might be slipping slightly not enough to be making a noise but enough to see a drop in the output of the alternator

 

[PSYKO PHOENIX]

sweet, what am i looking for while checking?

should i do it when the car is hot or cold?

 

[tt460]

You do it when the car is turned off, I would start with cleaning the battery terminals, disconnect the negative terminal and give both the lug and post on the battery a light sand leave this disconnected so you dont short something out by accident and do the other end of the negative cable as well. now do the positive side of the battery and reconnect it, now move onto the alternator doing 1 terminal at a time and cleaning all the lugs connection on it and putting it back together before moving on to the next as you dont want to fry some thing. then do the engine to body earth wire doing both ends. Now you can reconnect the negative to the battery and start the car and check voltages again

 

[PSYKO PHOENIX]

sweet will do, and if this makes no differnce whats next on the list?