Alternator goosed?

[coullstar 0]

Morning all. I hadnt used the car for a week or so and took it out for a spin on Wed night. After 20min or so I noticed the dashboard lights were dim and the car was idiling about 1100rpm (normally 800rpm). I took it to work yesterday and after 10min of stop start traffic it started idiling @1100rpm again. On the way home it did the same.

 

I went to pick up some wheels last night and it did it again with the revs fluctuating slightly. On the way home when I was giving it some gas the battery light was coming on. Eventually the lights dimmed and the car conked out on the busiest street in the middle of Aberdeen. It was dead. Gave to 10min and it restarted so I drove it the 5min home but it was doing it again.

From what I can read its the alternator however is there anything else it could be? The car has been reading low temps and I do have an ABS light on but Ive checked thermostat and Im sure the ABS thing is just a sensor or one of the rear rings as I did the rear brakes recently.

 

I cannot acutally get to the alternator to check it so it there a way to check as to replace it it looks like Im going to have to take the front of the car off :( which might not be possible with a gammy hand and the fact I park on a main street. Sometimes I wonder why I bought this car.

 

As per my sig the car has a 4motion engine and not the normal VR.

[coullstar 0]

Just measured the voltage at the battery, 11.3v before starting (slow starting) and dropped to 10.98v when running. :(

[mic_VR 3]

Surely if it was the alternater completely kaput once it was dead it wouldn't have the power to start again as it wouldn't have been charging? :scratch:

 

Sounds more like the belt is slipping so it's not charging completely, especially under load. You getting any squealing or strange noises? Might be worth checking the tension on the belt if you can get a hand in there.

[coullstar 0]

Tesion seems to be ok, I thought they had an automaic tensioner anyway? If not how do I adjust it?

[tedman 0]

sounds the same as my old golf when the alternater went. hope its fixed soon mate

[coullstar 0]

Im 95% it is that. Phoned VW and there are two options, Bosch or Hitachi. One is £203+vat and the other is £250+vat :shock: .

[davidwort 0]

if just one or two of the diodes go down in the alternator then it can charge partly, but you won't be getting full voltage, are you sure the brushes/voltage regulator are not at fault?

[coullstar 0]

To be honest I wouldnt have a clue how to check. Im next to useless with the witchcraft that is electrical stuff.

[davidwort 0]

To be honest I wouldnt have a clue how to check. Im next to useless with the witchcraft that is electrical stuff.

i'm not sure about the VR6 ones but the 4 cyl bosch ones have a round black plastic module on the end, with two side bits that each have a phillips mounting screw, undo these two screws and the unit comes off the alternator, with the two carbon motor brushes/contacts attached underneath, very simple to remove and refit and if the sprung loaded brushes are really short they won't make proper contact with the motor and you'll get dodgy charging, brush packs are usually about 10-20 quid new.

[coullstar 0]

To be honest I wouldnt have a clue how to check. Im next to useless with the witchcraft that is electrical stuff.

i'm not sure about the VR6 ones but the 4 cyl bosch ones have a round black plastic module on the end, with two side bits that each have a phillips mounting screw, undo these two screws and the unit comes off the alternator, with the two carbon motor brushes/contacts attached underneath, very simple to remove and refit and if the sprung loaded brushes are really short they won't make proper contact with the motor and you'll get dodgy charging, brush packs are usually about 10-20 quid new.

 

Cheers. I think I'll need to get the slam panel off or something similar to get access to it. Joys of having a big engine.

[Jim 2]

Don't buy a new one. Get the old one off and sent to an alternator refurbishing place. Tempest got his refurbished by a local company here in Coventry for under £100 and he's very happy with the work they did.

[Joe M 0]

I think the alternator has just gone on mine as well, battery light came on on the dash last night. Ive checked the battery, 12v ish before starting, 11.6 when running. Ive taken the fat power cable off the alternator and theres 0v at the bolt where it attaches. :(

[coullstar 0]

Yep, pretty much exactly what mine is like.

[Joe M 0]

I dont know what its like on the 24v, but with mine it looks like it should be easy enough to remove from underneath, would save you from taking the front end off?

[coullstar 0]

Yeah but the car is stuck on my street so I can only really work on it from the top. Joys of living in the city centre I suppose.

[coullstar 0]

Ok I managed to get a look at this tonight and scored a new alt for a bit less than the dealers were wanting. Even if it isnt this one at least I now have a spare as they are apprently prone to failure on the 24v.

 

Anyway I have read through some previous post on alt removal and i reckon if i get the drivers headlight out I might have enough room to get in there to disconnect. Easiest way for me would be to unbolt the front mount and jack the engine up to get it out.

Question is do I just have to undo the bolt in the photo below and the engine can be jacked up? Also where is best to jack up from with a bit of wood on the jack and how much movement can you realistically get?

 

Note its a Vibratec front mount.

[pete_griff 0]

yes if you just wind that bolt out that oyu can see (although you may want to loosen, but not undo the other engine mount bolts as well to allow for more movement), then you will be able to jack up the engine; best place for that would be on the corner of the sump.

not sure if you'll get enough clearance to get it out like that (certainly going to be an awkward way of doing it!), you'll just have to try i guess.

if it was me i would just take the front off, given how easy it is...

[_leon_ 0]

how much work is it to remove the manifold on a 24v? is removing it from the top with the manifold off not an option? granted on the 12v you've got to undo the front and rear mount and jack up to get a lower bolt freed

[coullstar 0]

Looks a bit of a PITA. If I get it up axle stand I rekcon I can release the alt form the top and maybe pull it out from underneath to save mucking about with engine mounts.

 

Im kind of limited in what I can do as Im living on a main street with limited parking plus the car would probably only get 100yrds up the road before conking out.

[coullstar 0]

Does anyone know roughly how long a fully charged battery might last? If I get the car to my parents house ~60miles away on 90% dual carriageway then I can work on it no bother.

 

Im pretty sure that I drove to and from work + a little extra before it died, that was about an hour and half so I might be ok. Anyone else done this?

 

Is there anything I can do to limit the impact on the battery other than no lights, fan, stereo etc? Will disconnecting the lead to the alt do anything?

[davidwort 0]

I think a knackered alternator can actually drain the battery, depends on what's gone on it, if the diodes are fubar'd then it may well be draining, does it get warm at all all by itself, like overnight?

[coullstar 0]

I checked the battery level yesterday and it was exactly the same as before so I dont think anything is draining the battery.

The car hasnt moved since last Friday. Im going to go for it. Speaking to a few folk they have done this before so I reckon its possible. Just need to get the battery out and get it charged up.