Alternator problem

[Brotok]

The car is a '79 911 SC. Yesterday in the morning I noticed the car was making a high pitched buzzing/whining sound in high RPMs. By night time the red alternator light started coming on at low RPMs but would go away at high RPM. I replaced the voltage regulator less than a year ago. Any advice on how to go about this? Also, I have a 1 hr drive home today - opinions on whether the car can make it?

Many thanks for the help.

[86 911 Targa]

Originally Posted by Brotok

The car is a '79 911 SC. Yesterday in the morning I noticed the car was making a high pitched buzzing/whining sound in high RPMs. By night time the red alternator light started coming on at low RPMs but would go away at high RPM. I replaced the voltage regulator less than a year ago. Any advice on how to go about this? Also, I have a 1 hr drive home today - opinions on whether the car can make it?

Many thanks for the help.

Need more info:

1. Voltage at battery with the car running. (13.8-14.5)?

2. Loose belt?

Drive the car without any accessories.

Good luck,

Gerry

[Brotok]

Thanks for the reply.

I haven't had a chance to check the voltage at the battery.

I checked the belt and it is fine.

Best

[vash]

where are you located? 1 hr drive? i agree, it depends on what voltage you are seeing at the battery.

if it were me, i would charge up the battery on my cell phone and go for it...unless my route took me over any bridges..then no way.

[Daviboy]

Brotok,
I can almost gaurantee you that your alternator bearings are shot. Mine did same thing and when I pulled the fan and alternator the actual winding core had been rubbing on the inside of the two case halves (hope this is making sense). Not only did I have that problem but the brushes had also started to self destruct. One issue I did notice when I pulled the alternator was that the black plastic dust cap/centraliser was missing. This I did not even know about till I did some searching, I had noticed a gap around the alternator rear bearing and housing and wondered why. Now I know if this bearing is unsupported it puts excessive lateral force on the front bearing thus destabilising it. Upshot is my alternator was stuffed have a new one on the bench waiting for me getting home....

[Brotok]

Interesting. Thanks for that explanation. Guess I will have to pull the alternator and see. Any chance this might just be a bad ground or something like that?

[Daviboy]

Brotok,
If your really lucky. Would not account for the buzzing/whining sound at high rpms. Mine was doing the same, at lower rpms the belt spins the alternator with less lateral force on the shaft, higher rpms the shaft is under more lateral load hence pulling the core downward. I almost bet when you pull it the core has been rubbing on the lower side of the housing.

[Brotok]

Thank you all for your advice.

I removed the alternator today. Turns out the part where the brushes make contact was worn to the shaft. I replaced the alternator and all is now well. Also, I managed to make it home safely before the thing died completely.

Happy motoring.

[Hendog]

I was wondering how this turned out...glad to see you made it home and then was able to fix it.