alternator problem??

[GQ Bear]

My alternator wasn't charging battery and was reading low voltage on dash. Down as low as 6V at one stage.

Anyway i pulled it apart and replaced brushes, old ones were about 6mm. New ones about 20mm long. anyway was running beautifully upto 14v for a couple of days and now it's only showing about 11-12V.

I'll have to now pull the bugger apart again. Could the brushes have been shite or something or do you think it may be regulator perhaps? Any way of testing these components?

I didn't sand smooth the rotor?? thingy's that the brushes contact on. Could these have been a bit scored or something and therefore causing a problem?

Thanks

ps it's a Hitachi 70amp LR170?? alternator out of a 92 4.2L efi Nissan Patrol

[Thylacine]

First thing to check now would be your battery. If you've pulled it down that low it's very likely U/S. You're local auto sparky should test it for free.

When replacing brushes it pays to check the rotor for scoring or uneven wear. A fingernail ran along a surface is a good check for scoring in metal. If theres wear there it'll chew through your new brushes a lot quicker, so worth cleaning up any wear with some fine emery.

ed

[Wish I had coils]

i would say regulator, my alt was fix new brushes and bearings worked perfect for about 5-6 months now it is reading 11-12 volts.

my mate pulled the reg of and opened him up and it was nice and toasty. by the sounds of it that might be your prob.

Been told that it can wreck your alt to if the reg is gone and i think thats what i have done. i put new reg in and it still reads 11-12 volts so i may have burned something in the alt

Hope this helps