Z4 Alternator woes (Cured)

[gookah]

So the missus got back today in her E85 Z4, handed me the keys, and said the red battery light was on. About 6pm.
I got in and no lights on other than parking brake, which went off when it was released.
However I noticed the middle interior light was left on.
I was busy decorating at the time, so decided to give it a quick run along the local dual carriageway to give it a quick boost.
So about 3 miles from home the dash lit up with yellow lights abs, tyre pressure, traction control. then the front camera display started flickering. I pulled off at the next slip road as things got progressively worse, parking brake light on, but now flashing yellow/red.

Then power steering went altogether!!!! followed by the headlights then the engine started missing. I struggled to just about get onto a nearby Wickes car park, with everything in darkness.
switched off and tried to restart but all dash lights dim and click from starter.
Called the missus and asked her to bring the spare battery and socket set.
When she arrived I swapped the battery over, and everything working perfectly again.
Put headlights on main beam, heater on and revved it , but I couldn' t make out the brightness of the lights increasing.
So I got home to the garage and put the meter on it. 12.4 volts with no engine on,
Started engine and dropped to 11.9v
Revved engine and no change. put lights on and voltsge dropped further to 11.4.
So no output from alternator.
Belt still on , alternator turning, no noises, just no output.


Can do without buying a new Bosch alternator at the moment at over £200, as just spent that on wallpapering and have a new car deposit to pay!

Has anyone solved this by just replacing the voltage regulator?

Otherwise options include:

New voltage regulator.
New cheap complete alternator.
Second hand genuine full alternator.
I went the second hand route with a starter motor and that has done 2 years without issue.


anyway, there I am on Wickes can park, freezing in just a short sleeved t-shirt, trying to swap a battery in the dark, when the missus said, oh yes the battery light was on yesterday it was yellow!!!!!
So, I could have just put a coat on, and got the meter out at home in the garage..!!

 

[t-tony]

So the missus got back today in her E85 Z4, handed me the keys, and said the red battery light was on. About 6pm.
I got in and no lights on other than parking brake, which went off when it was released.
However I noticed the middle interior light was left on.
I was busy decorating at the time, so decided to give it a quick run along the local dual carriageway to give it a quick boost.
So about 3 miles from home the dash lit up with yellow lights abs, tyre pressure, traction control. then the front camera display started flickering. I pulled off at the next slip road as things got progressively worse, parking brake light on, but now flashing yellow/red.

Then power steering went altogether!!!! followed by the headlights then the engine started missing. I struggled to just about get onto a nearby Wickes car park, with everything in darkness.
switched off and tried to restart but all dash lights dim and click from starter.
Called the missus and asked her to bring the spare battery and socket set.
When she arrived I swapped the battery over, and everything working perfectly again.
Put headlights on main beam, heater on and revved it , but I couldn' t make out the brightness of the lights increasing.
So I got home to the garage and put the meter on it. 12.4 volts with no engine on,
Started engine and dropped to 11.9v
Revved engine and no change. put lights on and voltsge dropped further to 11.4.
So no output from alternator.
Belt still on , alternator turning, no noises, just no output.
View attachment 173263

Can do without buying a new Bosch alternator at the moment at over £200, as just spent that on wallpapering and have a new car deposit to pay!

Has anyone solved this by just replacing the voltage regulator?

Otherwise options include:

New voltage regulator.
New cheap complete alternator.
Second hand genuine full alternator.
I went the second hand route with a starter motor and that has done 2 years without issue.


anyway, there I am on Wickes can park, freezing in just a short sleeved t-shirt, trying to swap a battery in the dark, when the missus said, oh yes the battery light was on yesterday it was yellow!!!!!
So, I could have just put a coat on, and got the meter out at home in the garage..!!

Don't you just love it when that happens. So when you were biting your tongue did you get right through it Pete.

Tony.

ps. And yes, I would try a new reg. for the alternator.

 

[gookah]

bless her.....

 

[g8jka]

I struggled to just about get onto a nearby Wickes car park, with everything in darkness.

Wickes shuts at 4 on a Sunday, probably why everything was in darkness.

Should have called me, I'd of been happy to take the 5 minute walk down. I'd have spent at least half an hour there with you, could have done with a good laugh.

Sold that 1 series a few weeks too early.

 

[Althulas]

They certainly do try us.

 

[Stevo7682]

Have repaired Bosch alternator twice now on my vag group car .
Both times carbon brush pack in the regulator worn right down £20 fix rather than nearly £200 for an exchange unit.

 

[colb]

Agree try fitting a new regulator, should be able to do it with the alernator still in the car.

https://www.motor-doctor.co.uk/alternator-regulator/brand-bosch

 

[gookah]

I have ordered a new voltage regulator.
The reason I wondered at first whether it would cure the problem was because I thought it would just be a collection of resistors and other electronic components.
But I now see that it is more the fact that it contains a new set of brushes..

However, thinking it might be stuck brushes, I gave the alternator a few light taps with a mallet, worth a try, but no difference.

So I decided I would take the regulator off. Loads of room after removing the airbox.
I then took of the main red cable (battery has been disconnected)
I then unscrewed the black plastic cap on the engine block side to get to that stud and nut. I undid a small Phillips screw at the bottom that holds on the plastic, and tried to remove it, but it was not budging. I wondered if it was still held on by the nuts on the posts.
I then set about taking the nut off the main terminal post, it was very tight and I was wondering if this was correct.
After a large amount of force it turned, but it then appeared that the post was loose, Oh s*** I have snapped it off inside, I thought.

So off came the whole alternator. a job I was trying to avoid.

When I got the alternator off I saw the plastic cover was indeed held on by the nut on the main terminal, and another nut on the terminal post to the right hand side.
Both nuts removed and the cover came off.
This time both posts came loose, but they are captivated, so it was normal, and the alternator didn't need to be removed after all.


Anyway got the VR off and there appears to be plenty of life left in the bushes, and there was also plenty of spring force pressing them against the commutator.







Now I hope it's the electrical components after all.

New VR arrives Wednesday.

 

[t-tony]

Probably a burnt out diode Pete. Good of you to show how to not remove the Alt. too mate.

Tony.

 

[gookah]

So, heres the update.

The new voltage regulator arrived.
Whilst it was off, I checked for a circuit between the left hand pin in the socket and the horseshoe terminal.
On the new one it was 4.5 m ohms
On the old one, open circuit, so there's an encouraging difference.
Also there was resistance between the l/h pin and the brushes on the new one, but open circuit on the old one.

Refitted it and started the car,
Output is now 14.5 volts, not 11.4v, hence now charging the battery.
Yay!

Then plugged in INPA and cleared numerous low voltage errors, which did not return..

Great result for £29.

 

[t-tony]

Good result mate, at a bargain price.

Tony.

 

[Althulas]

Good info to share

 

[colb]

Good fix, saved a mint over a replacement alternator, must get around to fitting a replacement on my old alternator thats sitting on the garage shelf. That was replaced as a whole unit when its output dropped to 12v on my Z3. Low mileage car so bearings in it sound and feel ok, preety sure a regulator change will sort it.

 

[t-tony]

Most common cause of alternator replacement according to my tame Auto Electrician friend.

Tony.

 

[g8jka]

Now get rid of it and buy a Z3.

 

[gookah]

the other way round I'm thinking......

 

[Philpatton]

Out of curiosity, where did you buy the replacement voltage regulator? Was it from a regular motor factors such as GSF or ECP?

 

[gookah]

eBay

12V ALTERNATOR REGULATOR FOR BMW Z4 E85 OEM F00MA45219 12317515319 - Bosch Type | eBay

Find many great new & used options and get the best deals for 12V ALTERNATOR REGULATOR FOR BMW Z4 E85 OEM F00MA45219 12317515319 - Bosch Type at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[Philpatton]

Good old fleabay!

Thanks
P

 

[Stevo7682]

Great news .
A relatively cheap fix on an expensive replacement part is always welcome.
That should give your alternator a new lease of life for the foreseeable future.
Stephen.