Battery light on. How to identify alternator model/brand?

[Scott ZHP]

Originally Posted by andrewwynn

That's a great tip about the captive nut. I thought it was just a threaded hole in there block.


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I've also used a giant socket on the outside end of the ear and pulled it; but the mallet works just as well. I do this with the ear supported from the back also with a large socket, so theres no risk of breaking the ear off.

[oldskewel]

Originally Posted by Scott ZHP

The trick to reinstalling the alt easily onto the bracket is to refit the long mounting bolt (on the bench). Spray it with penetrating oil and lightly whack the bolt head a few times with a deadblow/rubber hammer. This moves the sliding nut back a few mm and is easily refitted. The captive nut is made to slide. Don't get carried away, a few light taps are all you need.

Also, there are at least two different Valeo alts depending on the options/packages, maybe 100amp and 140 amp. If you have heated seats, you def have a 140amp.

My 2001 3.0i has a Valeo 120A. Good tip on figuring out the amp rating as well as Bosch-vs.-Valeo.

[jac]

The plastic housing on the back side of the alternator does not have any markings besides the B+ and B-. I am also unable to see how to remove that housing to even attempt access to the regulator, so I am just gonna remove the whole thing.

Now, to remove the alternator, I guess I need to remove the fan shroud and radiator fan too? Otherwise I don't see how I can get clearance to move the tensioner pulley to losen the belt. I see I need a T50 male socket to move it and the socket alone is like 1.5 inches long so I can't fit the breaker bar nor ratchet without removing the fan. :-(

[jac]

@oldskewel: thanks for that photo. I was trying to do this all from above, so I have not looked underneath yet. Maybe there's a sticker on the underside of the unit... will check, right after lunch. :-)

[cn90]

I you replace the alternator, time to replace the OFH Gasket as well.
I posted the photos in forum.

[Scott ZHP]

Originally Posted by jac

The plastic housing on the back side of the alternator does not have any markings besides the B+ and B-. I am also unable to see how to remove that housing to even attempt access to the regulator, so I am just gonna remove the whole thing.

Now, to remove the alternator, I guess I need to remove the fan shroud and radiator fan too? Otherwise I don't see how I can get clearance to move the tensioner pulley to losen the belt. I see I need a T50 male socket to move it and the socket alone is like 1.5 inches long so I can't fit the breaker bar nor ratchet without removing the fan. :-(

I stuffed my phone down there and took a whole bunch of blind pics; my white label was still intact, so it was easy to tell from one of the 20 random pics I got.

Been a while since I replaced mine, but yes you need to detension and remove the belt. First, remove the shroud fasteners at the top and but leave the shroud in place. Then remove the fan clutch (it's reverse threaded) from the water pump snout and remove the fan/clutch and shroud together; do not bang it into the back side of the radiator. Do the same sandwich on reassembly. To make alt removal easier, loosen the long bolt 3 or 4 turns, then whack it gently as indicated above; makes removal from the OFH bracket sooooo much easier.

[andrewwynn]

I remove/replace my alternator from the back. To do this I remove all the intake hardware from the snorkel through the intake boot and the DISA,also the aux coolant pump I disconnect the attached point so I can move that around to make more room. It will fit mostly straight up once moved maybe 20 cm aft.

[Clavurion]

Originally Posted by andrewwynn

You’d have to have at least one extra joint in your fingers to remove the VR in place. I wanted to do that very badly.

Not sure on E53 but at least on E46 and E39 with M54 engine this can be done in situ. (Also done it on my E53 but with M57N engine.)

For example this video shows what you are looking for to remove the back cover and then change the brushes.

https://www.youtube.com/watch?v=aVvPzwtxdrM&t=25s

[oldskewel]

Originally Posted by jac

The plastic housing on the back side of the alternator does not have any markings besides the B+ and B-. I am also unable to see how to remove that housing to even attempt access to the regulator, so I am just gonna remove the whole thing.

Now, to remove the alternator, I guess I need to remove the fan shroud and radiator fan too? Otherwise I don't see how I can get clearance to move the tensioner pulley to losen the belt. I see I need a T50 male socket to move it and the socket alone is like 1.5 inches long so I can't fit the breaker bar nor ratchet without removing the fan. :-(

I pretty much always do stuff from above, and am sure I did it from above for the alternator. My alternator (120A Valeo) looks EXACTLY like @upallnight's pic in post #2 - with the "Valeo" cast in the middle just like that. Since you don't see that, maybe it is encrusted in oily dirt or maybe it is missing and you have a Bosch.

I don't know the numbers, but one clear difference between Bosch and Valeo is the pulley diameter. But probably easier to just pull out the alternator.

I agree on doing the OFHG while you are in there.

I can't remember on fan removal. I've now removed and replaced that thing enough times that I barely think about it. BUT, if it is your first time on that, don't underestimate that step. If the previous person torqued it on there, it may need special tools to remove it. If not, you just need a 1-1/4" open end wrench (slightly tighter, at 1-1/4"=31.75mm than the 32mm spec wrench would be, so it transmits the impact a little better) and know how to hit it just right. I bought the special pulley holding tool for the first time I ever removed it, and have not used it since.

Also, on diagnosis ...
if your voltage readings (that you are not sure about) are correct, then yes, that is a clear indication of a charging problem.
And a charging problem is *probably* caused by the alternator (but could be other things)
And if it's a problem with the alternator, depending on mileage, it is probably as simple as worn brushes, which are part of the voltage regulator. If you get that far and don't want to replace the whole alternator, just replacing the VR or the brushes may be a cheaper solution.

The Bosch and Valeo will be interchangeable as a complete unit, including VR and pulley. But the individual components of the Bosch vs. Valeo assemblies will not be interchangeable. E.g., Bosch VR will not work on a Valeo alt.

I just found some links I saved. First one is a thread from when my alternator went out. Many photos. The other xoutpost thread shows many pics and a tutorial for the Bosch. Maybe seeing those photos of the Bosch and the Valeo will help you decide which one of those two options yours looks more like.

https://xoutpost.com/bmw-sav-forums/...3-0i-01-a.html

https://xoutpost.com/bmw-sav-forums/...-pictures.html

https://www.bimmerfest.com/threads/d...ebuild.516680/

https://www.bimmerfest.com/threads/v...eplace.514504/

[oldskewel]

Originally Posted by Clavurion

Not sure on E53 but at least on E46 and E39 with M54 engine this can be done in situ. (Also done it on my E53 but with M57N engine.)

For example this video shows what you are looking for to remove the back cover and then change the brushes.

https://www.youtube.com/watch?v=aVvPzwtxdrM&t=25s

I watched that guy's great videos. Very interesting and impressive. I even bought the full rebuild kit (brushes, slip rings, bearings) from him on eBay. Ships from Ireland, so not good if you are in a rush. I think I did a quick VR swap when my alternator failed, and then bought his kit, and then when I had the engine apart later, it was convenient, so I did the rebuild.

Actually, looking through the video just now, I'll say that the back cover, etc. all look completely different vs. what mine does. Once you get deeper in there for the rebuild, everything he says applies, and the video is good. Apparently Valeo used the same brushes and slip rings on every alternator they made for about 3 decades (don't quote me on that, but I wish other manufacturers did not reinvent the wheel as much as they do).

And I won't doubt that *you* can do it in-situ, and if I really needed to do it to win a bet, I could probably do it too. But given a choice, and knowing what I know so far, I would remove the alternator.

On the tightness of the alternator when reinstalling, I've just cleaned up all the surfaces, and use anti-seize on a few key spots, and have never found it to be a big problem - e.g., no machining required. But I'll also say that probably due to being in California, I tend to have a lot less corrosion on everything vs. most of the photos I see of other engines.