Replacing alternator

Grumple

Grumple

Member
Hi All,

After months of trying to work out why my A2 failed to start on several occasions, and doing all kinds of (erroneous) tests, my battery light has finally turned on permanently and there's under 12v at the battery with the engine running - dead alternator me thinks!

I've found a decent refurbished option on ebay (£90 px) - Here

How easy is it to replace? Are any 'special' tools required?

Other than a new belt, is there anything else I should replace at the same time?


Considering just letting a garage fit it all for an hours labour, unless it's a genuinely simple/straightforward swap.

Thanks in advance!
 
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Decent socket set so you have enough leverage is the main thing. The biggest issue is usually holding the belt tensioner back (from my experience replacing alternator on my Tdi) as you really need three left arms to be able to undertake the process cleanly.

Other thing is that it may be a good idea to spray the threaded ends of the bolts securing the existing alternator to the mounting bracket with a penetrating spray before trying to remove them - I had one bolt snap off just shy of the head which resulted in my local mechanic having to cut the old alternator off with a plasma cutter before replacing it.

Tensioner may also be a good idea to replace as well (if a Tdi) the over-running pulley (should this not have been done)
 
Good Afternoon,

The link for the replacement alternator yields an Xtool scanner?????

I assume you've done your homework on the required amps.

Andy
 
Unless your alternator sounds like a bag of spanners it's quite likely that it's just the voltage regulator module that has failed. You still need to remove the alternator to replace that of course ... If there is any chance that your thermostat needs replacing, it's MUCH easier to do that while the alternator is off. (I'm assuming you have aTDi).
 
Disconnect the battery first.

My garage charged me £72 to swap over an alternator.
 
Thanks Robin - it's wrestling with the tensioner and risk of shearing bolts that makes using a garage quite tempting!

I think the alternator is supplied with a new pulley (if that's the one you mean). I'll try and find the tensioner.

I think this is the correct belt number, but there's wildly different prices coming up online: 045903137D

Alternator part number is 045 903 023G
 
AndyP said:
Unless your alternator sounds like a bag of spanners it's quite likely that it's just the voltage regulator module that has failed. You still need to remove the alternator to replace that of course ... If there is any chance that your thermostat needs replacing, it's MUCH easier to do that while the alternator is off. (I'm assuming you have aTDi).
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Hi Andy, I don't think it sounds great tbh, but the engine has always sounded a tad rough - I just assumed as an old diesel that was standard.

Thermostat changed a few years ago with alternator in-situ!
 
Size 16 spanner on the tensioner nut to release its tension, need a long handled spanner, ideally ring spanner, as access bit slim down side. 30-40 cm ring spanner will make it easy job. Or from underneath car not too bad with long handle socket.

Altenator easy to remove gerally just spray release agents on aas much thread as you can see first. And mark the belt for direction is refitting.
 
Andrew said:
Good Afternoon,

The link for the replacement alternator yields an Xtool scanner?????

I assume you've done your homework on the required amps.

Andy
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I thought that did something weird - link updated.

I'm just replacing like for like? It's a 140A
 
16mm Metric L Shaped Angled Open Hex 6 Point Socket Wrench https://amzn.eu/d/72jwSNU

Best £10 I spent with an extension bar from my socket set made easy work of releasing tension and using a 5mm Allen key to lock off the tensioner in position to remove the belt .


If you’re replacing the regulator the original alternator won’t go back in position without moving out the inserts . A bolt washer and nuts can be used to push them back out again
 
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!
 
Certainly not the first time the alternator appears to work correctly but is faulty. They are renown from draining the battery long after the car has been turned off and frequently trigger the alarm as the battery is drained.
 
I have noticed the "battery" charge light takes noticeable longer to extinguish on our Silver car than my on our black car. Would say it's worth making sure engine earth is good but both mine have identical additional earth's fitted to ensure this is not the problem
 
It's sounding like a relatively doable job at the moment... I'll see if I can move the tensioner with what I've got, and take it from there!
 
Howey said:
I have noticed the "battery" charge light takes noticeable longer to extinguish on our Silver car than my on our black car. Would say it's worth making sure engine earth is good but both mine have identical additional earth's fitted to ensure this is not the problem
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I've seen the additional earth mentioned in various threads, but haven't managed to find a guide for it anywhere.

The only earth point I found info for is this one in the engine bay beneath the coolant tank:

20230507_181450.jpg
 
Grumple said:
I've seen the additional earth mentioned in various threads, but haven't managed to find a guide for it anywhere.

The only earth point I found info for is this one in the engine bay beneath the coolant tank:

View attachment 107888
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Ooooo, that looks like it needs replacing, it will aid your car no end... remove the bolt, give the chassis, cable and the bolt a damn good clean, then re fit it...
 
Even better remove the bolt and clean the bolt, remove the nut from the other end and REPLACE the earth lead. Very good chance there is bad internal corrosion under the insulation. Be careful not to snap the bolt.
 
audifan said:
Even better remove the bolt and clean the bolt, remove the nut from the other end and REPLACE the earth lead. Very good chance there is bad internal corrosion under the insulation. Be careful not to snap the bolt.
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I had to replace the earth cable for a customer not so long ago, you could see where it had been arcing for some time to the chassis...The cable was black inside when I stripped it, so glad I had a new cable ready to be fitted.
 
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!
 
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