Alternator Change

[SJon]

I need to swap out my Alternator on an A4 B7 2.0 TDI, but I'm having trouble with the serpentine belt tensioner, which means I can't get it off the alternator.

I've tried to put a 17mm spanner on the bolt circled here, but when I rotate clockwise, the bolt just slips, and there's no reduction in the belt tension.

I guess I'm missing something? The videos on YooToob all show the petrol engine which has a slightly different tensioner requiring variously a 17mm, 18mm and 19mm wrench. Ideas would be really welcome. This should have been a fairly straightforward job.

 

[northpole]

you need to use a ring spanner or a very shallow socket on a wrench to move it. both will keep a grip on the bolt . Using an open ended spanner just makes moving the tensioner out of the way harder to do... also you want a spanner/wrench you can slide an extension over to make moving it out of the way easier.

 

[SJon]

Thanks. Turns out the reason it was slipping is because it's 16mm, so by using the right tool, I was able to get it sorted.

None of the videos seem to have this particular alternator, which is a pain. The Alternator is fixed by 2 forward facing bolts, which get stick on the radiator fan cover, I managed to get the top one out with a small amount of surgery to the radiator cover, but the bottom one is stuck 90% out, pushing near the centre where there's some leads and thing, I'm stopped for the evening before I damage something out of frustration. Just this one bolt, and the computer control leads to get off (yes, that's stuck too) and then in the immortal advice of Haynes, instillation is reverse of removal... Ha ha.. This was supposed to be a 1 hour job.

Any advice on the bolt or the electrical lead would be well received.

 

[northpole]

Dude you need to loosen the engine mount on that side and lift or lower the engine, just to get that bolt out... (movement is done with a proper trolley jack) thought you already knew that.

 

[SJon]

Mate, I'm learning this stuff as I go along, I'm not a car mechanic. I've been riding and repairing big motorbikes for the past 20 years until my accident.

My last car had a carburettor

None of the videos I found showed raising or lowering the engine mount just to get a damned bolt out. Is there a decent spot to put the jack? I've got the straight forward type that I use to lift the car to change the wheels and brake pads, and I have a flatbed one I used to lift bikes off the ground by their frames.

Damn.

 

[northpole]

Piece of wood ontop of it than position it under the oil pan. I suggest you use a trolley jack. Both for safety and because it has a bigger contact.point than the standard scissor jack. But if you can use the motorcycle platform jack even better... I just hope you have removed the bottom engine cover already.

Maybe if you remove the airbox you are able to get it off but slim chance on mine it was the chassis leg that stopped it from coming out.

 

[SJon]

Thanks. The bottom cover is on because of snow, but I've had off previously, it's not too difficult. Ok, I'll use the bike jack, that'll spread the load a bit better. It's flatter when down too so easier than the trolly jack, I wouldn't use a scissor jack, too wobbly.

Ok, looks like I have a plan for tomorrow. Thanks.

 

[SJon]

Tha ks a lot man. With your advice, a whole lot of swearing, a bit of blood, and a lot of sweat, I've managed to get the new alternator in place and it's working fine.

So much for a quick swap out, but it's done

 

[northpole]

Yeah somethings can't be done quickly because the lot is to close to the unmovable chassis components.
Anyway I figured you'd sort it out quick enough once you start the job and you got a bit of direction.

 

[tr7]

Yes it's 16mm. I've just done this myself the other night.

We cut the ring end of a 16mm spanner off and used the open end and a pipe over the other end to slip the spanner onto the but and be able to get the access and leverage without having to strip any other parts or move the frontend into the service position.

Just removed the timing belt cover to give a little more wiggle room.

p.s. Spray some soapy water on firstly the belt, then the tensioner and then the alternator pulley. I went to the length of replacing the tensioner as it was moving about quite a bit and making fair bit of noise, but it appears now in the end to be in fact the alternator that's the issue. (So did a ton of work and faff for nothing)