Advice please. My car has just died!

Tue Mar 27, 2018 2:44 pm

A few days ago I was driving along and I noticed that the dashboard warning lights coming on, but very faintly. I had the alternator belt replaced 4 weeks ago, so I assumed that the belt hadn't been properly tight enough. Yesterday the car wouldn't start. So, today, I swapped the battery out and put in a spare, and then drove it to my local garage (not the same place that changed the belt) who said that it was the alternator that is knackered (not the belt tension).

Then, on my way home from the garage my car suddenly lost all power and died! I am about 300m away from my house. And I can't find the tow eye (should it be in the boot where the jack is stored, or is there a secret hiding place for it?).

Anyway, does anyone have any idea about what the problem might be? I didn't think that a non-functioning alternator could stop a car from going along!

Any help would be greatly appreciated! Thanks.

Tue Mar 27, 2018 3:56 pm

If the battery voltage falls below a certain level and the alternator isn't charging, ultimately the ECU will stop operating, hence the car not starting.

Tue Mar 27, 2018 4:06 pm

Speedtouch wrote:If the battery voltage falls below a certain level and the alternator isn't charging, ultimately the ECU will stop operating, hence the car not starting.

Thanks for your reply.

But in fact the car stopped dead in its tracks as I was driving along - all of a sudden I lost all power. So, it's not that the car isn't starting, it's that the car stopped suddenly in the middle of the road. (Of course, the car isn't starting now either...)

Tue Mar 27, 2018 4:19 pm

Your alternator isn't charging the battery so your fuel pump would also have stopped working eventually and the car will cut out. The car isn't starting now because the battery is flat.

Tue Mar 27, 2018 4:53 pm

Contours wrote:Your alternator isn't charging the battery so your fuel pump would also have stopped working eventually and the car will cut out. The car isn't starting now because the battery is flat.

Okay, so it must be the alternator in that case. Thanks.

But it seems kind of dangerous that a car could just lose all power and stop right in the middle of the road.

Tue Mar 27, 2018 6:17 pm

Without the alternator charging the battery, the threshold voltage eventually drops too low for the ECU to be able to drive its logic circuitry, hence it will just abruptly cut out things like the fuel pump, injectors, etc.

Tue Mar 27, 2018 6:59 pm

Did the garage replace/repair the alternator?

Tue Mar 27, 2018 7:53 pm

Brianmoooore wrote:Did the garage replace/repair the alternator?

The garage told me he'd get a quote to me by the end of the day. My car broke down on my home back from the garage!

He has now given me a quote and he'll order a new alternator tomorrow. I just have to get the car to him - hopefully a fully charged battery should be enough to get me there.

Tue Mar 27, 2018 9:01 pm

Take the air filter assembly out of the way, unscrew the regulator from the back of the alternator, gently pull on the carbon brushes, put it all back together, and it'll probably be fine for at least 12 months, assuming your alternator has suffered what is by far the most common failure.
I was wondering if the garage had removed the battery connections in the course of their work, and maybe not put one of them back properly.
Fully charged battery will last longest if you keep lights, wipers, radio, heater fan, etc. all turned off.

Tue Mar 27, 2018 9:16 pm

Brianmoooore wrote:Take the air filter assembly out of the way, unscrew the regulator from the back of the alternator, gently pull on the carbon brushes, put it all back together, and it'll probably be fine for at least 12 months, assuming your alternator has suffered what is by far the most common failure.
I was wondering if the garage had removed the battery connections in the course of their work, and maybe not put one of them back properly.
Fully charged battery will last longest if you keep lights, wipers, radio, heater fan, etc. all turned off.

Thanks for the advice. Are you saying that the car would run fine without the regulator?

And with regards to the battery connections, are there not only 2 of them (the + and the - ) and both were on the battery and tight.

Sorry if my questions are silly, I am an E30 newbie!

Thanks.

Tue Mar 27, 2018 9:31 pm

The usual cause of E30 alternator failure is that the carbon brushes that feed power to the alternator's rotor have worn away. If you remove the regulator pack (two small cross head screws) you will see the two spring loaded carbon brushes, which are retained in place by short lengths of flexible copper braid.
When the brushes were new, and much longer, the braid was squashed up behind the brush, but now, the braid on the shortest brush will be fully extended, and the brush end will no longer be making good contact with the copper commutator on the rotor. There will probably be signs of arcing on the end of this brush.
If you pull the brush gently, you will stretch the braid more than the spring alone can manage, and it will now sit a mm or two further out, and make good contact again when refitted.
This extra mm or so will wear away in time, but will give several months of normal use until it fails again - time that can be used to source a replacement regulator at a good price.

Tue Mar 27, 2018 10:01 pm

Brianmoooore wrote:The usual cause of E30 alternator failure is that the carbon brushes that feed power to the alternator's rotor have worn away. If you remove the regulator pack (two small cross head screws) you will see the two spring loaded carbon brushes, which are retained in place by short lengths of flexible copper braid.
When the brushes were new, and much longer, the braid was squashed up behind the brush, but now, the braid on the shortest brush will be fully extended, and the brush end will no longer be making good contact with the copper commutator on the rotor. There will probably be signs of arcing on the end of this brush.
If you pull the brush gently, you will stretch the braid more than the spring alone can manage, and it will now sit a mm or two further out, and make good contact again when refitted.
This extra mm or so will wear away in time, but will give several months of normal use until it fails again - time that can be used to source a replacement regulator at a good price.

Thank you for that - that's really helpful and good to know.