Audi a4 b5 2.4 blue. Car tag says 8gl as alternator code. Thats a 120 amp, but could either be a valero or Bosch. I cannot find the original part #. But I have found a diesel alterator, same size engine. 120 amps. 059 903 015g Valero It looks the same, same mountings, same electrical plug/cable
And a 90 amp Bosch, same mountings. But the wiring plugs are different, both are just a big fat cable and a single wire. 058 903 016
I'm thinking that the diesel alternator is the same except for maybe the pully size, which can be swapped.
Is there difference between a diesel alternator and a petrol one? Thanks/m
intrade,
Oct 18, 7:20pm
dont know but did you look a new one up at www.rexbo.eu They have usually pictures and coross reference what other cars it also fits.
budgel,
Oct 18, 7:59pm
Valeo is the brand.
marte,
Oct 18, 8:02pm
There's seems to be sight differences in pully size. 64.5mm - 65mm - 66mm
And maybe the diesel alternator has a extra output wire for the rev counter, that's just from reading about diesel vs petrol alternators on the net. Both 14 volts, lol
bigfatmat1,
Oct 18, 9:08pm
Valeo and Bosch should be interchangeable. Check the pin configuration just to be sure it is marked on each alternator
aredwood,
Oct 19, 1:24am
Check which direction the pulley spins. If the alternator has a clutch, and the drive belt spins it the wrong way. It won't work.
Also diesel alternators often have a vacuum pump fitted to them. Check if the diesel alternator has one fitted, or if the car it is intended for has the vacuum pump directly on the engine instead.
You will also need to check if that single wire is for the ECU to vary the alternator output. Or if it is just the wire that goes to the battery warning light.
marte,
Oct 19, 10:04pm
I got under the car today and removed the back black plastic panel. Its possible, 2 small bolts and the one wire plug and the fat red cable. Got the regulator/brushes out to find its a tiny slip ring, and the brushes have worn back to almost nothing. One slip ring is discoloured and that brush is oxidised on its surface. Deciding to find out if the brush can be replaced, I found the burnt brush just crumbled when I grabbed it with pliers. Its wires soldered into a crimped brass tube, grinding this off will let me unsolder the brush. Its 6.35m (lol) x 4.5mm rectangled.
The Valeo part has [ VL2 ] & [2547] [61778] & [228] in a circle on it.
A most important part I missed at the start is that the car has done 293,000kms. ….
marte,
Oct 19, 10:19pm
The first warning signs that things were not right is that the red battery light came on, on the dashboard after a short trip. The next day out acted normally, then later on, came on again. I figured it might just stop playing up by itself. But it didn't, it got worse over a week and then stayed on.
This makes sense knowing now that it was bad brushes. And 293,000 kms is 'Brush time'.
I also found out today that the one little wire that runs to the dashboard battery light, also controls the 'excitation' (?) Of the alternators field. Unplugging it saves a bit of power if the alternators brushes are buggered. And, if you change the wattage of that bulb, it changes the output characteristics of the alternator.
And, surprisingly, you can just change the slip ring for a new one on these.
bigfatmat1,
Oct 19, 10:20pm
It is possible just yo cut the tip off pull brush and lead out drill hole and resolder. It's been arcing that is why it is discolored however this creates hardness on the copper and uneven wear. The slip ring needs to be machined if within wear limits it will be ok if not a new slip ring fitted. Just to note though bearings life span is usually around same length as the brushes. If the slip ring is left it will wear through if it's wear is excessive or if out of round from arcing will break the brush leads. It's important to have a reliable alternator. Imo you need to remove alternator and fix it properly just fitting brushes may cause a more expensive failure down the track
bigfatmat1,
Oct 19, 10:24pm
Changing bulb wattage does not change output you could take bulb out once running and see no difference in charge it's solely excitation ie to start the process of charging some alternators self excite. Once the charging has started the alternator outputs 12v on the warning light wire this is why the light goes out. Newer alternators do not use this method as they are ecu controlled
marte,
Oct 19, 10:43pm
I got the info about changing the bulb wattage from a book today, it could have ment that the alternator 'comes on' quicker. Not sure now. Quite sure that I'm not doing it though.
Also, just found this info on changing the brushes itself, specifically for this alternator. Exactly the same brush regulator setup.
From what they say, it's the same unit that's on lots of valeo alternators. Since the 2nd hand one I bought, the diesel one, is arriving soon I wil compare them and see what differences there are. I think the brush pack is about $50-$60 worth. Since the slip rings are worn, I will check out what's needed to be done there as well.
Its all quite a education.
marte,
Oct 21, 11:05pm
Well, I bought some brushes for it instead, $5.50, + $6 p&p.
Refitted the brushes into the regulator and put it back together. It works! For $5.50 I fixed something that could have cost me hundreds of $$ (In fact, it most me $50 for a car electrition to tell me " Its probably the alternator". In truth, I should have got under the car and started having a proper look first. And $70 for a alternator that I don't need now, and has brushes that need replaced very soon anyway. For a cost of $5.50 + p&p) I will try buying the next brushes from 'Automotive Supply's group NZ Ltd' They have a huge selection of brushes and alternator/car electrical stuff and it would be worth trying them out as a new 'contact'. Online catalogue too.
elect70,
Dec 17, 10:41am
^^ exactly , they arent interested in fixing them , rather sell brand new @ $500 than spend an hour at $50 & $5 worth of parts . Theyl cite the CGA as the reason but thats just a cop out . Still a few old school places around but getting less every day as the old boys retire .
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