alternator light in 911sc

[fredmeister]

Had noticed a slight whirring noise from my engine at idle the other day. Thought it might be the belt on the fan or the aux heat blower motor. The car is a 79 911SC.
Anyway, the sound got progressively louder though the belt was not slipping nor showing signs of burning. The alternator light started coming on dimmly at idle and would go out at higher revs. Finally after 20 more miles or so it would be on steadily at anything under 4000rpm. The belt still looks fine and the fan is still running at normal speeds so I don't think it is alternator bearings.
What else would wear in the alternator to make it stop functioning and make that noise?
Is it possible to rebuild the alternator myself without resorting to buying a rebuilt unit at $300.00 or more?

[304065]

Brushes.

If it's the original alternator you might just have it overhauled anyway. You could change the brush holder (79's are externally regulated so there's no integral regulator, just a brush holder) but chances are the bearings might go in a few thousand miles. Also, an alternator shop will check out your commutator and make sure it's smooth.

There's a good auto electric shop near you- I used to live in B'ham and had my 2002's alt rebuilt there. Can't remember the name but it was something like import auto electric.

[Jdub]

Pull the unit and get it to a rebuild shop. They will probably charge in the vicinity of $125.00 to replace brushes, turn down the commutator ring, and whatnot.

Keep the external regulator unit you have. It may put out less amps but the external reg. makes it a breeze to get to.

John

[scottb]

Fred: A local rebuild shop did mine for $89. The R&R isn't very difficult. Wayne's book has a good section, and there's an article here online. Also, you might consider sending the shroud and fan out for polishing and powdercoating while you have it apart.