Alternator advice

[Dougalo 0]

My battery light stays on when i start my 16V until i give it a good rev. During these cold mornings it has been staying on for longer and longer. Whilst the battery light is on the blower (and all other electrical things) are weak. As soon as I give it a good rev everything is back to normal. It's been like this for a couple of months now and the car has never not started so the alternator must be charging a bit. Does this sound like my alternator is on the way out? I've been reading about Diode packs - could this need replaced?

Cheers

[Supercharged 2]

Check the belt tightness and condition first off...

 

If you can unscrew the pack the brushes should be about 1cm I think... these packs are about £10 from any autoelectrician.

 

Also measure the voltage across the battery with the engine running... should be between 13.8 and 14.5

[davidwort 0]

My battery light stays on when i start my 16V until i give it a good rev. During these cold mornings it has been staying on for longer and longer. Whilst the battery light is on the blower (and all other electrical things) are weak. As soon as I give it a good rev everything is back to normal. It's been like this for a couple of months now and the car has never not started so the alternator must be charging a bit. Does this sound like my alternator is on the way out? I've been reading about Diode packs - could this need replaced?

Cheers

 

The 16v alternator diodes are inside the unit and nor really replacable, the voltage regulator and brush pack is the black 50p sized unit on the end of the alternator, held in with 2 phillips screws, as supercharged says, they are worth changing if the brushes are really worn down, but if you get less than 13.5V when the engine is running (no electrics on) then one or more of the diodes may be shot and it's time to get a whole exchange unit (you should be able to get a second hand one for around 15 quid, but they may go the same way soon!).

You need to check the battery with a voltmeter, just to make sure it's not the little blue wire from the alternator to the dash that has a dodgy contact or broken wire as that controls the dash light, but from what you describe it seems more likely that the brushes, belt tension or diodes are getting a bit ropey.

 

David.