Series 3 Alternator

[300AJC]

My S3 started first time this morning and I used it for about 30 minutes. I tried to restart it and dead. I had to get the AA out. He diagnosed an alternator fault. I had all the lights on and heater due to the weather this morning and so he recommended a new alternator. The battewry was drawing about 10v and not 12.

Could it be just the belt? As winter is coming in would I be wise to upgrade the battery AND alternator?

 

[oxides]

You should be seeing about 14 volt at the battery with the engine running, 12 1/2 volt stationary with no drain. Could be either or both are knackered. You need to charge the battery and get its capacity checked. Then check the alternator output. A buggered battery can drag the alternator down even if it's OK.

 

[TheKeymeister]

Check the thin wire going to the alternator plug, mine was cracked in about 5 places thanks to its proximity to the exhaust.....without that the alternator won't produce any power

 

[300AJC]

Thanks chaps.

 

[300AJC]

I'm probably going to change the battery when I change the alternator. Is it fair to assume that a knackered battery could ruin an alternator and visa versa? Would a Halfords job be as good as any or can someone recommend a really good battery for an S3/

Thanks.

 

[oxides]

If it's a diesel get as good a battery as you can afford, if it's petrol almost anything that will fit will do. Try changing the battery first - you might find the alternator is OK.

 

[300AJC]

It's a petrol so I trip to Halfords it is then. As it's parked on the drive during the week a frined of mine that has a weekend off road Defender recommends an Optimate 3 whilst parked on the drive.

 

[oxides]

Unless you've got any extras (alarm, radio etc) there's no drain on the battery with the ignition off so it'll retain charge for months, possibly years. You won't need a really expensive one like a modern car.

 

[philvy]

Unless you've got any extras (alarm, radio etc) there's no drain on the battery with the ignition off so it'll retain charge for months, possibly years. You won't need a really expensive one like a modern car.

There's always the starting handle, innit?

 

[dominicbeesley]

I'd replace the alternator wires (both) that go from the alternator to the solenoid/battery and also check the ground lead then recheck voltage at battery with engine running - make sure the engine is revving at about 1500rpm too, my new alternator doesn't kick in until I give it a bit of right foot. I recently forked out for a new alternator to find that one of the ends wasn't crimped on tight enough and knackered a good battery in the process!

Also, I'd avoid Halfords for batteries as the own-brand ones have let me down in the past, our local factors (Andrew Page) have decent "cheap" but good ones for £50 or a 95Ah Bosch one for about £80 with a five year guarantee...and they knew which one instead of looking blank when you mention any motor more than five years old...

Dom

 

[300AJC]

Thanks again.

 

[borristherat]

if you need an alternator i have just purchased a recon engine that had a ,i am told, working alternater on it. the alternator on my origional engine has just been replaced. if you can give me a couple of days to confirm it works you can have it for the cost of the postage.
good me.

 

[300AJC]

That's a really kind offer but I've just ordered a new one. However, I hooked up my battery to my late father's electric golf trolley battery charger overnight, I had nothing to lose. It started first time this morning!! God bless ya dad; still helping me out!

 

[300AJC]

My very first attempt at vehicle maintenance started today. What a bugger!! It took about 2 hours to take out the old alternator today and much cursing. I found it very fiddly trying to get a socket on the bolts and a spanner on the nuts but finally did it. The whole of the underside of my S3 seems to be covered in a layer of mud and wax oil as well, so fun all round. I managed to put the new alternator in place but I am having a hell of a job getting it lined up correctly to receive the bolts. The lack of daylight forced me to give up for the day.

Things I have learned:

1. It's never as easy as they say in a Haynes manual or show on the internet.
2. It's not that easy trying to do these things on a sloping drive.
3. It hurts when I whack my head on a) the gravel and b) the underside of my S3.
4. It's 'kin' cold.

I expect you seasoned pros are having a laugh, but I will get there!

 

[borristherat]

no getting at those bottom bolts is a pain in the arse, it took me a good couple of hours to do mine.

 

[300AJC]

I'm sure it will all be worth it. It's a weekend drive only and I want it to start on a saturday morning so a new alternator and battery will be a good idea this time of year. I've got the old one out and the new one in place so hopefully a couple more hours swearing and cursing should do it!

 

[borristherat]

I'm sure it will all be worth it. It's a weekend drive only and I want it to start on a saturday morning so a new alternator and battery will be a good idea this time of year. I've got the old one out and the new one in place so hopefully a couple more hours swearing and cursing should do it!

yep swearing and smacking of heads goes hand in hand with series ownership i think.
from memory i think the way to test the belt tension is it should wiggle an inch up and down when correctly tensioned, over tight knackers bearings and to loose knackers belt.
your right, its defo worth doing the battery as well, if they fail its allways when it starts to get cold.

 

[TheKeymeister]

Are you struggling to get the front and back bolts to mount the alternator bracket?

You should find there's a metal bush type thing in the rear mounting lug, bit of gentle persuasion with a hammer and it will tap out, allowing it to slide onto the bracket. Just be careful not to snap the lug off the alternator and if you tap it too far and the alternator is loose, tap it back the other way!

 

[300AJC]

Cheers. I think it might be easier to offer up the bottom bolts first and leave the top one 'til last. There's obviously more "play" with that one in order to adjust the belt tension.

 

[borristherat]

Are you struggling to get the front and back bolts to mount the alternator bracket?

You should find there's a metal bush type thing in the rear mounting lug, bit of gentle persuasion with a hammer and it will tap out, allowing it to slide onto the bracket. Just be careful not to snap the lug off the alternator and if you tap it too far and the alternator is loose, tap it back the other way!

yep thekeymeister is bob on, i forgot about that little brass sleeve, you do need to tap it a bit to open up the gap between the two bottom brackets of the alternator for it to fit. if you support the alternator bracket on a socket when you "persuade" it into place you reduce the risk of damaging it, make the gap a bit bigger than it needs to be and than tighten the front bottom bolt first then the when you do the back bottom bolt it will pull the sleeve back tight to the engine bracket.
i suspect that the sleeve is what is making it difficult to fit.