Replacing alternator

[Robin_Cox]

I'll be honest chaps, cleaning it is no issue, but replacing an earth cable sounds a tad beyond me at the moment...

New alternator has arrived. Tensioner moves enough for me to slip a belt on and off (hopefully), so I'm gonna give this a go tomorrow.

I'm assuming the process is something like:

1. Disconnect battery
2. Remove engine cover (Any need to detach the coolant pipe? It just seems in the way...)
3. Release tension and remove belt
4. Remove fixing bolts (how many are there?)
5. Unclip cable connectors
6. Reverse of above to install replacement

Thanks all!

1) Good idea.

2) Coolant pipe? Do you mean the L-shaped metal air return pipe from the intercooler to the rear of the engine? - this wraps around the front of the Tdi engines. Undo the three fixings and the engine acoustic cover will take off with the intercooler pipe in situ although there is usually a bit of wrangling with the edges as you manoeuvre it under the cabin air intake trumpet. I've taken it off when replacing thermostats and coolant temp sensors however I cannot remember having had to do so when removing alternator as you have access from the side.

3) yes. It may be easier to remove the tensioner completely (three bolts to undo it, M8/13mm from memory). If you aren't replacing the belt removed with a new one, before removal put a piece of tape on it with an arrow indicating which orientation it currently is in so that it can be replaced the same way round - I've read enough times that re-installation in the reverse direction can cause major problems.

4) there are two long bolts that secure the alternator to the bracket. The threaded ends are in the vicinity of the thermostat housing - give these both a good squirt of WD40 or Plusgas / penetrating oil the day before trying to undo them preferably if they haven't been taken out before - one of mine was seized in place (galvanic corrosion over 19 years) and snapped off just below the head when I got some proper leverage onto it.

5) yes

6) yes.

Obviously open to correction. Best of luck!

 

[PlasticMac]

1) Good idea.

2) Coolant pipe? Do you mean the L-shaped metal air return pipe from the intercooler to the rear of the engine? - this wraps around the front of the Tdi engines. Undo the three fixings and the engine acoustic cover will take off with the intercooler pipe in situ although there is usually a bit of wrangling with the edges as you manoeuvre it under the cabin air intake trumpet. I've taken it off when replacing thermostats and coolant temp sensors however I cannot remember having had to do so when removing alternator as you have access from the side.

3) yes. It may be easier to remove the tensioner completely (three bolts to undo it, M8/13mm from memory). If you aren't replacing the belt removed with a new one, before removal put a piece of tape on it with an arrow indicating which orientation it currently is in so that it can be replaced the same way round - I've read enough times that re-installation in the reverse direction can cause major problems.

4) there are two long bolts that secure the alternator to the bracket. The threaded ends are in the vicinity of the thermostat housing - give these both a good squirt of WD40 or Plusgas / penetrating oil the day before trying to undo them preferably if they haven't been taken out before - one of mine was seized in place (galvanic corrosion over 19 years) and snapped off just below the head when I got some proper leverage onto it.

5) yes

6) yes.

Obviously open to correction. Best of luck!

If you need penetrating oil, I have a can.
Mac.

 

[Grumple]

Thanks Robin!

Ah, my bad - I just remember seeing a pipe that looked radiator size in my way!

New belt going on.

I'll drown the threads with WD-40 in the morning and see how the bolts move after a few hours.

 

[Grumple]

If you need penetrating oil, I have a can.
Mac.

Thanks mate - I should have a can (or two...) in the garage but I'll be in touch if not!

 

[Grumple]

Right, this went just about as smoothly as I could hope - bar some stubborn bolts and tricky belt replacement!

New alternator is pushing a consistent charge to the battery, and charged it to 12.5v after a short drive.

For anyone that this might help in the future:

1. Disconnect battery
2. Remove engine cover
3. Unclip and move air return pipe (it will make life way easier)
4. Use 16mm socket/spanner on tensioner to release tension and remove belt
5. Soak the visible parts of the bolts securing the alternator AND tensioner with WD-40 and leave to work it's magic (repeatedly if necessary)

The bottom bolt for the alternator is covered by the tensioner, so you will have to remove it as well (unless my bolts were on backwards?!)

6. Undo 3x 13mm tensioner bolts and remove
7. Undo 2x 13mm alternator bolts and remove (it might be wedged on pretty well, the wheel bolt spanner makes an excellent lever!)

8. Replace in reverse order - to get the belt back on you will likely have to lock off the tensioner. There's a small hole that you can insert an Allen key or screwdriver in to hold it in place, but I couldn't move it anywhere near enough for this, so wedged it with the trusty wheel bolt spanner!

I'd personally advise using short hex (not bi-hex if possible) sockets with a short but strong ratchet - these bolts want to strip and get rounded off...

The threads for the bottom bolt are difficult to lubricate, but you can squeeze the long nozzle tube of a WD-40 can through a small gap that runs along the bottom of the alternator.

It's easy with the right tools - Good luck!

Thanks to @PlasticMac for rescuing me with a decent socket set!

 

[Mandydingle]

Right, this went just about as smoothly as I could hope - bar some stubborn bolts and tricky belt replacement!

New alternator is pushing a consistent charge to the battery, and charged it to 12.5v after a short drive.

For anyone that this might help in the future:

1. Disconnect battery
2. Remove engine cover
3. Unclip and move air return pipe (it will make life way easier)
4. Use 16mm socket/spanner on tensioner to release tension and remove belt
5. Soak the visible parts of the bolts securing the alternator AND tensioner with WD-40 and leave to work it's magic (repeatedly if necessary)

The bottom bolt for the alternator is covered by the tensioner, so you will have to remove it as well (unless my bolts were on backwards?!)

View attachment 108075

View attachment 108077

6. Undo 3x 13mm tensioner bolts and remove
7. Undo 2x 13mm alternator bolts and remove (it might be wedged on pretty well, the wheel bolt spanner makes an excellent lever!)

8. Replace in reverse order - to get the belt back on you will likely have to lock off the tensioner. There's a small hole that you can insert an Allen key or screwdriver in to hold it in place, but I couldn't move it anywhere near enough for this, so wedged it with the trusty wheel bolt spanner!

View attachment 108073

I'd personally advise using short hex (not bi-hex if possible) sockets with a short but strong ratchet - these bolts want to strip and get rounded off...

The threads for the bottom bolt are difficult to lubricate, but you can squeeze the long nozzle tube of a WD-40 can through a small gap that runs along the bottom of the alternator.

It's easy with the right tools - Good luck!

View attachment 108074

Thanks to @PlasticMac for rescuing me with a decent socket set!

Hi, thanks very much for this very useful post, I’m doing this job atm, just wondering if you have any tips on refitting the alternator, it’s a very tight fit

 

[audifan]

Make sure the floating bushes are in the correct position. As the bolt is tightened it then draws the bushes into their final position.

 

[Grumple]

Hi, thanks very much for this very useful post, I’m doing this job atm, just wondering if you have any tips on refitting the alternator, it’s a very tight fit

Yep, as audifan said - the bushes/sleeves that form the inside of the bolt holes on the alternator can be pushed outwards a bit to make more space between them.

Detach/remove that air pipe too.

 

[Kyojitsu]

Thanks all for the advice on here - very helpful. Contemplating doing this job due to a noisy alternator - think bearings are about to give up. It's a metallic, hollow 'ringing' that changes with engine speed, and putting a long screwdriver between it and my ear and it doesn't sound good in there. No charging issues or warning lights (yet). Am I better off replacing the whole unit or have any of you replaced bearings only? Is it worth it?

 

[Kyojitsu]

Just to add some experience having just completed this job - replacing the alternator is a breeze provided you've soaked the bolts as suggested above. By far the biggest issue for me was the tensioner. A giant pain in the a**e. The nut on mine was made of chocolate and under load rounded off very easily. A six point hex I think is essential and preferably a longish offset type to get sufficient leverage - it's a very strong spring. Check you have the right spanner as it'll save you a headache.

There's very little room (naturally) so a 6 pt socket and 1/2" breaker bar won't fit horizontally. I ended up buying a new tensioner in the end due the nut being so rounded (which was probably needed tbh) but it shouldn't be that hard should it? Perhaps I've missed something...?

Anyway good luck - it's a very straightforward job but for that and if anyone has some tips on the tensioner I'm all ears.

PS The hollow ringing I described above was indeed the alternator bearings. Sound has now gone and just the purring of the 1.4TDi can be heard...

 

[AndyP]

Just to add some experience having just completed this job - replacing the alternator is a breeze provided you've soaked the bolts as suggested above. By far the biggest issue for me was the tensioner. A giant pain in the a**e. The nut on mine was made of chocolate and under load rounded off very easily. A six point hex I think is essential and preferably a longish offset type to get sufficient leverage - it's a very strong spring. Check you have the right spanner as it'll save you a headache.

There's very little room (naturally) so a 6 pt socket and 1/2" breaker bar won't fit horizontally. I ended up buying a new tensioner in the end due the nut being so rounded (which was probably needed tbh) but it shouldn't be that hard should it? Perhaps I've missed something...?

Anyway good luck - it's a very straightforward job but for that and if anyone has some tips on the tensioner I'm all ears.

PS The hollow ringing I described above was indeed the alternator bearings. Sound has now gone and just the purring of the 1.4TDi can be heard...

I have a slightly dirty workaround for this same problem. Like yours the tensioning nut on mine is damaged and difficult to access, so I remove the tensioner just by undoing the mounting bolts. I then mount the tensioner in the vice and retension it using a 6 point socket, locking it in place with a (sacrificial) 3mm drill bit. Reinstalling is then dead easy and after tightening the bolts I cut the drill with a 1mm grinding disc - instantly retensioned !

 

[Kyojitsu]

I have a slightly dirty workaround for this same problem. Like yours the tensioning nut on mine is damaged and difficult to access, so I remove the tensioner just by undoing the mounting bolts. I then mount the tensioner in the vice and retension it using a 6 point socket, locking it in place with a (sacrificial) 3mm drill bit. Reinstalling is then dead easy and after tightening the bolts I cut the drill with a 1mm grinding disc - instantly retensioned !

Ha - funnily enough the new tensioner came 'opened' with a securing pin in place making the belt replacement easy. My mistake was using a spanner to take the tension and remove the pin - ended up with said spanner jammed against chassis and no means of releasing it. Had manhandle with hammer and a large crowbar to get it free. Won't make that mistake again...

 

[Gritty]

Evening folks

I had the pleasure of spending NYE on the back of a rescue truck after breaking down in Milton Keynes with blackpool illuminations on the dash,
Battery is good but Alternator not doing its job so Im now gona replace my ancient alternator and 7 year squealing starter and as Audi fan recommends I also wish to replace the two black ground wires that run from the alternator to the starter from the starter to the earth point under the headlight, can anyone one furnish me with these part numbers and where I can purchase them from please?

Thank you. Car is amf tdi 75 2002

 

[audifan]

earth line Audi A2 (A2) 2003 year Audi EUROPA 972000

earth line Audi A2 (A2) 2003 year Audi EUROPA 972000 spare parts

audi.7zap.com

 

[AndyP]

Evening folks

I had the pleasure of spending NYE on the back of a rescue truck after breaking down in Milton Keynes with blackpool illuminations on the dash,
Battery is good but Alternator not doing its job so Im now gona replace my ancient alternator and 7 year squealing starter and as Audi fan recommends I also wish to replace the two black ground wires that run from the alternator to the starter from the starter to the earth point under the headlight, can anyone one furnish me with these part numbers and where I can purchase them from please?

Thank you. Car is amf tdi 75 2002

Make sure it's not just the voltage regulator module on the alternator before you splash out on a new one. Unless your alternator sounds a like a bag of spanners it's likely ok. Most garages will just replace the alternator without checking (kerching!).

The other possibility is that the alternator clutch has detonated itself - also replaceable separately.

 

[willsoffe]

I don’t get it, I spent months trying to find the cause of the beeps and ABS light on my A2, changed all bearings, abs sensors, battery etc. Absolutely no starting issues or signs it was the alternator ….. but it was!

Hello team!

Reviving an old thread here…

1.4tdi 90bhp

Battery keeps running low whilst car is parked (and possibly when driving).

Various warning lights come on on the dash and go out at random. Limp mode sometimes.

This seems to point to an alternator fault? As everything seems ok after I charge battery overnight (from below 70% charge). Battery is brand new Bosch unit.

My question is: is it a case of replacing the alternator straight away, or is it worth replacing the alternator voltage regulator by itself first?

Cheers!

Will

 

[Indi]

Hello team!

Reviving an old thread here…

1.4tdi 90bhp

Battery keeps running low whilst car is parked (and possibly when driving).

Various warning lights come on on the dash and go out at random. Limp mode sometimes.

This seems to point to an alternator fault? As everything seems ok after I charge battery overnight (from below 70% charge). Battery is brand new Bosch unit.

My question is: is it a case of replacing the alternator straight away, or is it worth replacing the alternator voltage regulator by itself first?

Cheers!

Will

I’d check the system voltage with the engine running first, if over 14v then the alternator is likely ok. This can be done with a code reader/VCDS or presumably also just with a multimeter between the alternator terminal and the aluminium alternator body

 

[willsoffe]

I’d check the system voltage with the engine running first, if over 14v then the alternator is likely ok. This can be done with a code reader/VCDS or presumably also just with a multimeter between the alternator terminal and the aluminium alternator body

Great stuff thanks for the tip! Planning on checking this. And cleaning and refitting the earth strap. May aswell start with the basics!

 

[willsoffe]

Great stuff thanks for the tip! Planning on checking this. And cleaning and refitting the earth strap. May aswell start with the basics!

Report. So earth strap was toast. Lots of signs of arcing on the washer, it was burnt through in placed! As soon as I rubbed it back and refitted, the starter motor turned over twice as fast. Let’s see if the battery starts charging properly now!