E30 Zone

Hi,

Just removed the old Bosch alternator 0120469757.

Is it advised to go for a like for like replacement - same serial and 14V/80A?

Or has anyone installed something different? I have no heated seats and no aircon.

Cheers

Why have you removed the alternator?

(new) battery was not charging. checked battery and the readings were varying from min to max repetitively whilst running - concluded that the alternator must be faulty.. please correct me otherwise

Voltage regulator?

Yes, the alternator is 'faulty', but it's not a sealed unit. The problem is very probably simply worn out carbon brushes in the regulator pack, which is easily changed without even removing the alternator from the car.
The regulator is the round black thing on the back end of the alternator, secured by two small screws. Unscrew these, remove the pack and observe the state of the two carbon brushes. Odds are that one will be very short, with signs of arcing on the working end.
If this is so, gently pull on each brush, to straighten the copper braid inside the springs, then refit the regulator to the alternator and the alternator to the car, and carry on driving while you obtain a new regulator.
Google the Bosch number on the regulator, and you will find numerous places to buy a replacement. There's no hurry - it should last for many months after the 'stretching' treatment.

Fantastic advice. Will give it a go!

Hi,

Just changed the alternator and also have a new battery. Jump started the car and let the battery charge for over an hour - however, failed to crank once I restarted the ignition.

The instrument cluster lights up, wipers work etc on first turn of key but no crank.

Any ideas what to troubleshoot next?

Remove the cover on the diagnostic socket, carefully identify pins 14 and 11, take a piece of wire and briefly link these two pins together. This should crank the engine, regardless of if the ignition switch is on.

jspl109 wrote: ↑

Mon Jun 29, 2020 9:12 pm

Hi,

Just changed the alternator and also have a new battery. Jump started the car and let the battery charge for over an hour - however, failed to crank once I restarted the ignition.

The instrument cluster lights up, wipers work etc on first turn of key but no crank.

Any ideas what to troubleshoot next?

So you have a brand new alternator and battery and car still does not start?!

Does it simply not crank over and you hear a loud "click" noise? What is your battery voltage?

Jump starts fine. Doesn't crank from ignition afterwards. I hear no loud click noise.

Not checked voltage across the battery but will do first thing tomorrow morning.

jspl109 wrote: ↑

Mon Jun 29, 2020 9:50 pm

Jump starts fine. Doesn't crank from ignition afterwards. I hear no loud click noise.

Not checked voltage across the battery but will do first thing tomorrow morning.

Okay mate check battery voltage and let us know. A good battery should be a good 12.5v or more ideally

Checked the battery, it was 10.6V before jump starting. Once it was running, 14.3V so charging fine. Turning the car off and back on again, voltage now 11.5 V ! Although the battery is new (6 months) l, it's not holding charge. Definitely a rotten egg?

Put it on trickle charge for 12 hours.

Ben

Agreed battery is either dead or needs a good charge