I have come to realize that the research effort to make decisions like this, combined with the helpless frustration when something would go wrong ends up being pretty costly.

So I almost always try to rebuild things like this myself with proper parts. It almost always comes out perfectly, and when it does not, it feels a lot better to have screwed it up myself than to have paid someone else to do it to me.

Yes it takes some skills and knowledge, but gaining those are a good investment.

Great, I have seen post for rebuilding the alternator. Anyone try that? Can you rebuild the bosch or valeo? Do they sell the rebuild parts? Is it just not worth the effort? BTW, how do I disconnect the aux.heating tube above the alternator to the right? Is it a special connector, or do I just tug on it till it comes loose? Do you remove the upper coolant hose?
thanks

I would recommend just replacing with a rebuilt unit, usually around $200 for the part. Don't forget most places have a core charge too so you have to pay to ship the old one back.

Here's an M54 alternator replacement DIY that should help:



Or, you can watch the oil filter housing gasket DIY I did here on our X5 which is more accurate for the X5 model.

My son removed his alternator and took it to a shop that specializes in alternators and had it rewound and refurbished for half the cost buying a rebuilt one. His was a bosh.

You have rebuilt your own alternator? Wow. I did not that was even possible. Do you mind elaborating some on this? I am sure it is pretty involved, but I am still curious.

OK, got it out, not that bad except for the upper coolant hose. Ok, so Autozone is selling the 120 amp alternator - Duralast Gold, new , with Valeo manufacture/components.
249. , is this thing worth it? Will it really work with my X5 , 3.0 ? Will it last ? My original lasted 15 years, 217,550 miles..

This thread follows the entire process, from debugging, onward for my '01 E53.

http://www.xoutpost.com/bmw-sav-foru...3-0i-01-a.html

In that thread the first and main thing I was looking for was any clues on diagnosis based on the intermittent working vs. non-working observations. I did not get any help there, but here is the answer - that absolutely can be a symptom of worn brushes, which is already the prime suspect in any alternator failure. Basically, as the shorter brush has worn just to the limit, it is right on the edge, and if contact is made, current flows and the alternator works. If no contact is made, no current, no charging. The slightest temperature changes, etc. can put you on either side of that fence.

I've rebuilt other alternators on my cars, as needed, with new bearings as well.

Some comments for the x5 here:
- It can be very confusing regarding compatibility between Bosch, Valeo, what year, what amperage, what you've actually got in your car. First thing I would recommend is ignore all that and dig into your car far enough to see EXACTLY what alternator you've got in there (Bosch vs. Valeo, and how many Amps should define it). Guaranteed to be faster than trying to figure it out via normal methods, which would only get you to a 60% chance of being right.

- The water cooled alternators are very different.

- For mine, and I expect many of the air-cooled alternators, worn out brushes are likely to be the only problem.

- When you've got it on the bench, it may be worthwhile to replace the bearings as well, if you have them in hand. I ended up buying a Valeo rebuild kit on eBay (supposedly covers an incredibly wide range of Valeo alternators) with new slip rings, bushings, and brushes, that I saved for doing a full rebuild the next time I get the alternator out. I could not wait that long at the time, so I just bought a new VR, which includes the brushes, and swapped it in.

There are many references throughout this list and other BMW lists on how to do the rebuild. Really not hard to do - about the same difficulty as R+R'ing the alternator itself.

Another post following that repair:
http://www.xoutpost.com/1071539-post7.html

The one thing that I would be worried about with a rewounded repaired alternator is that it does not include the bearing replaced in the alternator. At some point that bearing starts to give and before you know it you are changing the alternator all over again. Just go with a bosch remanufactured premium alternator to get the best that the market can give you. Even the BMW one from the dealer are mostly remanufactured.

Success. Removed it. Ok, so Whats the deal with BMW alternators? Really that special?
It's an 120 amp Valeo that's 16 years old. Do I have to use Valeo? What about Bosch?
What about brands that state: "valeo compontent"?
It's an old X5 with 218K miles so I don't want to spend a bunch. The Daytona dealer wanted $617. for a Valeo/ BMW . What?

I got my brand new Valeo (180A I think) unit off of Ebay for ~$250 for a 4.4i. Just as a comparison for you.

Or, this popped up: BMW Parts and BMW Accessories | Bavarian Autosport

$299 for a new 140A Valeo unit from Bavauto. I used a 2004 3.0i as the criteria... verify it fits your truck first.