E30 Zone

I was driving along today when all the electrics decided to have a go slow.

Windows wound at half speed, indicators ran at odd speed, radio went off. After a while it just went. A few hours later it happened again. I tested the battery voltage and it was 6v! With the engine idling it was still only 6v, so the alternator clearly wasn't charging. I managed to nurse the car home by revving it a lot, and after 2 miles suddenly all the electrics came back to life.

So I guess that the alternator isn't charging at low rpm. Is this a classic knackered alternator sign?

Possibly but check the voltage regulator and the carbon brushes attached to the regulator first.

Unscrew the two little cross head screws on the back of the alternator, and remove the regulator/brush pack. I expect that you'll find that one of the brushes has worn too short to make proper contact with the commutator. Give it a tug to stretch its retaining wire a little, and put it back into the alternator.
This will normally make it work again for several months, while you source a new pack.

I'm getting slow!!

OK, good info there, thanks. I'll take a look tomorrow morning.

Well that was an adventure!
I made it about half way to the scrap yard when the electrics died.
I connected up the spare battery with jump leads, there was a bit of a spark, but I couldn't get the engine to turn over.
So I phoned up the breakdown service.


With nothing to lose, I removed the alternator from the car. I then undid the two screws that hold the brushes in place. Looking inside I noticed that one brush was shiney, whilst the other one had a darkened look to it. I guessed that this mean that there was poor contact, so I wiggled the brush aroud to encourage it out of its hole a bit more.

I put it all back together and tried starting the car. It was a bit slow turning, but it fired up and then sat there in steady idle.

I quickly put all the other bits back on, dumped the tools in the boot and drove to the breakers yard. It ran absolutely fine all the way there.

They had a completely reconditioned alternator for £85, so I bought that and swapped them over in the car park.

If you'd done this to the brush pack before you left home, you wouldn't have broken down - the alternator would have run fine for months.
All you needed was a new brush pack to 'recondition' (whatever that means!) your own alternator. Don't recall what they cost, but it's a lot less than £85!

Yes, but I also noticed a strand of loose wire on the commutator and couldn't be bothered to find out whether that was bad news or not. I've got a shiney alternator now, which obviouslly makes it work better.