Battery light on this morning

R

Robin_Cox

Member
As in the title ; car started absolutely fine ; idled a few minutes with Webasto on while defrosting windscreen, set off to drop daughter to school. Half way there, noticed that the battery light had illuminated. Car ran fine to school (didn't switch off), and back to home to take a different car to work ; what I've been able to check was that with the engine running the voltage was 11.85V rather than the more usual 14+. I'm assuming alternator (120A on an AMF with a/c), but apart from an occasional squeak just after startup (the bonnet drain pipe overhead is missing so I think it gets dripped on on wet mornings), it has run smoothly thus far and kept the battery charged without any protest - so I was wondering if the regulator could be in play here? Failed alternators on older cars gave various advance warnings including radio interference and complete seizure with the belt squealing which makes me wonder if it is something less catastrophic in this instance - not had a chance to look under bonnet yet due to work. Any suggestions on any other diagnostics blocks to check through OBD or obvious things to check for would be much appreciated (ie, is there a specific fault that would indicate regulator and in which menu if so?).

Many thanks, Robin
 
The pulley can be silent, squealing or sounding like a bag of spanners. It's also worth checking the whether the voltage regulator has packed up before buying a new alternator.
 
Clutch type pulley on tdi alternators Yes
Pop the belt off and feel for play
Regulator will probably be fine electrically but most likely the carbon brushes will be consumed, if the copper slip rings are ok a replacement pack will extend the alternator life
Can generally get one or two swaps before rings are compromised
 
During a recent visit to France, I noticed my battery warning light flashing. Lifting the bonnet, I found the pulley resting on the undertray and the belt wrapped around the alternator shaft! The alternator was still partly working with little or no belt tension - the tensioner was fully extended. A local garage repaired the alternator.

RAB
 
RAB said:
During a recent visit to France, I noticed my battery warning light flashing. Lifting the bonnet, I found the pulley resting on the undertray and the belt wrapped around the alternator shaft! The alternator was still partly working with little or no belt tension - the tensioner was fully extended. A local garage repaired the alternator.

RAB
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Exactly what happened to me on the Scottish social this year, just before we got into the really remote up the side of Loch Lomond. Luckily a place in Dumbarton took it in and fixed it on the Friday afternoon of the Bank Holiday weekend.
 
I think I have diagnosed the problem. The good news is that the alternator rotates freely and smoothly. The bad news is that someone seems to have pinched the belt..

Is it just a case of undoing the tensioner with those three bolts and then feeding a new belt around the various visible pulleys before putting it back together or is it more involved than this?
 

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Rotate tensioner clockwise and insert pin / twist drill to hold in retracted position
Fit belt
Release
16mm hex from memory and off set ring spanner is easiest, bit tight for a ratchet
If you have a bench vice it may be easier to remove tensioner from car

Are all pulleys running true?
 
Watch for the hex breaking off the casting. Had that a couple of times

I now have a home made tool that locks into the bc spaces on the casting of the tensioner abs NBC allows retraction of the tensioner without the use of the hex

Paul


Sent from my iPhone using Tapatalk
 
Belt replaced (found a Febi part number 28909 for 9 quid from one of my UK-Ebay regular supply places), new tensioner fitted as part of the process - releasing the pre-installed retention pin from above was interesting - a job best suited for someone with at least 4 arms, two of which double-jointed! Ended up clamping long locking pliers onto the pin while holding the spanner on the hex down in the space adjacent to the intercooler return pipe at arms length, then wiggling the locking pliers to gradually coax the pin to work its way out. After about 10 minutes of this with periodic stops to curse and uncramp my arm the pin clicked out and I managed to return the tensioner into position under control. Car started first time without battery light or noise .. job done.

With hindsight, worth noting as I don't have great spanners or socket extensions (too deep or too shallow or the wrong angle or just cheap) that although I was able to use breaker bars and various other combinations to twist the original, once I looked at the replacement tensioner I was no-where near able to generate the correct angle to have been able to put in a locking pin or drill bit and lock the original in place. The new one being pre-locked I was able to use a swan-neck 16/17mm spanner that engaged providing my fist was level with or lower than the alternator, with the tensioner fully bolted in (3 x 13mm bolt), then over-compress the tensioner while working the locking pin out. So - on balance, I could have done this without spending tens of quid on a tensioner - but would have probably needed to have invested three figures on decent tools (I have a mixture of stuff I accumulated from corner shops & Halfords as a student, inherited from Grandparents / Dad and odds and sods from online shops in the last 10 years) just to have achieved the same result.

Again, I keep thinking back to the observation that although the A2 is a modern car in many aspects, it is also in some senses not a lot more advanced than my student 2CV in terms of modularity - if you can use spanners (or appropriate bits / sockets) and follow simple instructions, you can keep it running and take bits on and off. I still can't understand why this appears to be the case much more so than Polos or 206s of the same era which seem much more opaque to me - unless it boils down to the support and knowledge here at A2oc that makes things seem easier than they actually are?
 
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I use a ring spanner with a length of 32mm plastic water pipe. Remove the pin with or without pliers, pull pipe upwards and let nature take it's course!

RAB
 
spike said:
Worth checking the alternator pulley first - https://www.a2oc.net/community/index.php?threads/bhc-engines-alternator-140a.33096/post-282853

Cheers Spike
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@spike - Thread resurrection, but it turns out you were right! A new belt that I fitted at the time of this set of posts worked for another 3 months before the pulley (that I have now realised my contemporary photo above showed lots of rusty dust coming out of the plastic cover suggesting it was failing internally already) sheared off completely in February. Replacement looks a pain because the internal remains of the pulley are obscuring access for the 33 spline locking tool, but I assume a bit of dremmelling to remove the excess should free this up.
 
@Robin_Cox Alternatively if your alternator has high mileage there could be bearing and brush issues so may be better to replace the alternator complete with new over run pulley
 
audifan said:
@Robin_Cox Alternatively if your alternator has high mileage there could be bearing and brush issues so may be better to replace the alternator complete with new over run pulley
Click to expand...

I disagree, a new alternator is hugely expensive, a new pulley and/or a regulator with brushes are a fraction of that. Check those first. Many people are sold a new alternator by a garage when the fix could be £30.
 
When you are having trouble removing the remains of the over run pulley it is not an expensive option.
 
I had similar trouble late last year in fitting the belt. After swearing a lot with the lack of leverage space and almost rounding the adjustment bolt, I ended up unbolting and removing the tensioner. This enabling me to get proper leverage whilst being held in a vice and I used a soft(ish) nail to slip into in the holes to hold it open. Refitted the new belt and rebolted the tensioner, then a 30 second hacksaw cut to release the nail and set the tensioner free. Quite satisfying, for once!
 
Since we're in alternator mode, may I sort of thread crash Robin?

On the Devon car, all starts fine and then after a few minutes the red alternator light comes up. There could be a crate of red herrings stinking up the place: it's not been on the road for over a year and has stood in a harsh environment since. The immobiliser has been bypassed, so that's another light up. The yellow brake disk symbol is up (looks like pad warning loom to me, will look at today), and I assume as a consequence, so's the glow plug light. Otherwise, it's all perfectly fine :D

Anyway, alternator fine when starting and then light coming up after a bit? Sticky brushes? No noises, although I see Robin mentions radio interference and there is a bit of that although I suspect aerial issues there (yeah, go on, put it on the list :rolleyes: ).
 
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