Battery light on this morning

Radio interference was on a failing alternator on my student 2CV 20 years ago - it sounded like a distant police siren when accelerating (that disappeared when the radio was switched off) ; nothing like that on this car. I do have a 140A spare alternator obtained off Ebay that I was planning to send for a refurb service, assuming that the alternator on the car would have seized completely, instead of which the one on the car spins as smoothly as a baby's posterior but doesn't have a pulley on it. Am just locating a baby hacksaw to clean up the end where the spline bit needs to insert as the car is too far from the house to get an extension for the Dremel. Weather also conducive to car work today at last.
 
audifan said:
You could also take off the bracket that holds the alternator onto the block if these bolts are accessable, alternator may slide off sheared bolt if others are out.

connecting and mounting parts for alternator; pol... Audi A2 (A2) 2003 year Audi EUROPA 903030

connecting and mounting parts for alternator<br/>poly-v-belt Audi A2 (A2) 2003 year Audi EUROPA 903030 spare parts
audi.7zap.com audi.7zap.com
Click to expand...

The diagram misses one critical feature - that the two bolts securing the alternator to the bracket pass through the alternator, the bracket, and then into an insert in the alternator at the back of the casing again. As the bolt has sheared off just inside the first pass through the alternator casing, it has left probably 70mm of thread locked into the back of the alternator that are also passing through the bracket so it is stuck, and wouldn't slide off even if the other bolt is released. If this was on a bench, it may be possible to twist this out with pliers, but bolted onto the engine the exposed part of the threads is nigh on inaccessible. The bracket also seems to be secured to the block by a number of big bolts, at least one of which is obscured with the alternator attached (by the look of it), and without removing the engine or the radiator panelling around the front I don't think I can get to these cleanly anyway - well beyond my mechanical ability. I'm going to try to replace the pulley, more or less the only option..
 
Bumping the thread as I experienced a similar thing today: battery light came on out of the blue. Car continued to drive and thankfully put me back home 10 km down the road. Battery read 11,5V with engine off and 11,75V on idle. So I guess the alternator is partially charging the battery, otherwise I'd never get back home?

I have had to change the belt ltensioner for some time, so I am concerned that increased forces to move the belt have destroyed the pulley, but at the same time there's no sound whatsoever, and everything moves on idle. No play in the pulley. Or is it a coincidental regulator error?

It's a 90A alternator, 1.4 AUA, so no clutch as far as I am aware.
 
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lavandism said:
Bumping the thread as I experienced a similar thing today: battery light came on out of the blue. Car continued to drive and thankfully put me back home 10 km down the road. Battery read 11,5V with engine off and 11,75V on idle. So I guess the alternator is partially charging the battery, otherwise I'd never get back home?

I have had to change the belt ltensioner for some time, so I am concerned that increased forces to move the belt have destroyed the pulley, but at the same time there's no sound whatsoever, and everything moves on idle. No play in the pulley. Or is it a coincidental regulator error?

It's a 90A alternator, 1.4 AUA, so no cluthes or bearings as far as I am aware.
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When the alternator stops on a petrol-engined car, every spark at the injector consume some of the battery content - it's only a matter of time until the overall voltage dips to a level where either it stops running (but more pertinently) that various ECUs get unhappy. On the Tdi it will quite happily run until you get home, although anything else consuming electricity will gradually run the battery down. Suggests your battery may have been both full at the time of failure and in reasonable health.

Actually - re-reading your message you still have an intact belt / alternator combo, but obviously your charge isn't as high as it might be - how old is the battery, and has the alternator / regulator ever been refurbished? Suggests that some fettling is needed ; on our AUA I regularly put the car on the CTEK charger / conditioner and that has massively reduced the incidences of voltage drops causing warning lights to come on spuriously, but the long term fix for this will be fitting a refurbished 110A alternator off a 1.6 FSi.
 
Robin_Cox said:
When the alternator stops on a petrol-engined car, every spark at the injector consume some of the battery content - it's only a matter of time until the overall voltage dips to a level where either it stops running (but more pertinently) that various ECUs get unhappy. On the Tdi it will quite happily run until you get home, although anything else consuming electricity will gradually run the battery down. Suggests your battery may have been both full at the time of failure and in reasonable health.

Actually - re-reading your message you still have an intact belt / alternator combo, but obviously your charge isn't as high as it might be - how old is the battery, and has the alternator / regulator ever been refurbished? Suggests that some fettling is needed ; on our AUA I regularly put the car on the CTEK charger / conditioner and that has massively reduced the incidences of voltage drops causing warning lights to come on spuriously, but the long term fix for this will be fitting a refurbished 110A alternator off a 1.6 FSi.
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Robin, thanks for the reply!
(and confirmation that I still had loads of luck to get back home without any heavy pushing).

Battery is 1,5 year old Varta Silver, 75Ah.
Belt is fresh, 2 months old.
Alternator age is unknown, but with experience of other parts I suspect it is still original, so 23 y/o 80k miles. No play in pulley, but brushes could be rather consumed at this point.

Battery charged to 13.5V on a smart charger, but dropped to 12.5V on idle and stayed so for 10 min more or less — so alternator does not charge it.

110A fit the AUA? Huh! Gotta check the article, because finding a 90A with a 56 pulley is a bit of a task, apparently.
 
Robin_Cox said:
When the alternator stops on a petrol-engined car, every spark at the injector consume some of the battery content - it's only a matter of time until the overall voltage dips to a level where either it stops running (but more pertinently) that various ECUs get unhappy. On the Tdi it will quite happily run until you get home, although anything else consuming electricity will gradually run the battery down. Suggests your battery may have been both full at the time of failure and in reasonable health.

Actually - re-reading your message you still have an intact belt / alternator combo, but obviously your charge isn't as high as it might be - how old is the battery, and has the alternator / regulator ever been refurbished? Suggests that some fettling is needed ; on our AUA I regularly put the car on the CTEK charger / conditioner and that has massively reduced the incidences of voltage drops causing warning lights to come on spuriously, but the long term fix for this will be fitting a refurbished 110A alternator off a 1.6 FSi.
Click to expand...

Even the tdi needs electrical power to run the injectors and the ecu
It will likely run longer than a petrol on the battery alone but will still stop eventually due to lack of battery power
The old school mechanical injection diesels would run happily without a battery


Sent from my iPhone using Tapatalk
 
The pulley on a low revving diesel will be smaller than on a higher revving petrol car, to give the most efficient alternator rotation rate. Id' think.
So don't fit a diesel pulley to a petrol, or vice versa.
Mac.
 
lavandism said:
Robin, thanks for the reply!
(and confirmation that I still had loads of luck to get back home without any heavy pushing).

Battery is 1,5 year old Varta Silver, 75Ah.
Belt is fresh, 2 months old.
Alternator age is unknown, but with experience of other parts I suspect it is still original, so 23 y/o 80k miles. No play in pulley, but brushes could be rather consumed at this point.

Battery charged to 13.5V on a smart charger, but dropped to 12.5V on idle and stayed so for 10 min more or less — so alternator does not charge it.

110A fit the AUA? Huh! Gotta check the article, because finding a 90A with a 56 pulley is a bit of a task, apparently.
Click to expand...
I did some poking around on this: https://www.a2oc.net/community/index.php?threads/alternator-findings-aua.50390/
 
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