Over charging

[GT1978]

I have a 98 rav that had a hard start the other week so i checked the alternator output and found it was outputing 15.3V. So i figure regulator has gone. Order a new one. New one puts out 15.1Volts? So maybe the sense wire is damaged giving false feedback? Nope. Have 15.1V at sense wire. So alternator is seeing the high voltage but not compensating. Is there something else that could be effecting the alternator output or did i just get a dodgy one?

[wilbo666]

Unlikely, but checked to make sure there isn't an issue with the sense pin in the alternator plug?

Cheers
Wilbo

[GT1978]

Might have partially solved it will have to wait and see. Just not 100% on what actually improved the output. I pulled the alternator out and pulled the back cover to check for any thing obvious. There was a dodgy assembled nut on the regulator that was over tightened causing its split washer to be squeezed out the side. I replaced this and checked all other nuts on regulator and brushes mounts. I also noticed the back cover had been eaten by the nuts that hold it on to the stator posts. I added some washes under the nuts on reassembly. Finally I reinstalled the alternator to test it again. The alternator this time gave only 14.8V at the battery and output terminal. Much better than the 15.1 - 16.5V that i had been getting. I then readjusted the alternator mounts to ensure good conductivity to earth and cleaned up a few of the earth connections between body and head. This dropped the voltage between the alternator body and the head from 4mV to about 1.6mV. On cold start the alternator still starts at about 15.1V but then drops to about 14.8V after maybe 30 seconds running. Still a little high but much more comfortable than 16V.