S52 Alternator Information

[robb1887]

So I've seen some people scurrying around for this info and my original thread was a bit messy.

So here is the info I know.

S52 equipped cars:
Replacement Bosch PN: AL9414X

Most parts stores will look your car info up and say they have an 80A or 140A that pulls up for our car. This is INCORRECT. These alternators are for E36 M3 S52's and DO NOT fit. The terminal block is on the wrong side of the alternator, & an air duct that doesn't make fitting easy. In a pinch you CAN clip a few wire ties and fit the unit and wires, I would only do this with the 140A unit in an emergency.

Our cars came equipped with either a Valeo or Bosch manufactured 115A unit depending on what BMW had at the time. The pulleys on these units are NOT interchangeable. One has a lip that fits inside the alternator casing the other does not.

If you are in the need of a new alternator the Bosch PN will give you what you need, or if you pull the alternator and leave the car your better bet is take them to a local shop that can rebuild them. Its usually cheaper.

[rf900rkw]

I just poked around a bit. Worldpac has it correct. Advance has it right for 1998 and 2001 models only. 99-00-02 give M3 alternators. O'reilly's is just hosed.


Local rebuild is always the best option. Unfortunately not many shops are left.

[BenFenner]

And since I went through this recently... IMO moving the wires around a little so the 140A unit can be used is a viable, and maybe even highly suggested course of action. You get a better alternator, can duct it if you want, it will be cheaper to source, and if you ever need to replace it in a pinch, you'll have tons and tons to choose from, instead of waiting long periods of time for the "right" unit which is not cheap.

[mnguyen84]

does worldpac sell to regular customers? i often see them selling to autoshops

[Mr Bingley]

I installed a 140 amp unit in my VF supercharged S52 with S54 oil cooler--now that was a tight fit which required re-routing the wiring, a Bosch pulley, removing a couple of cooling fins off the side of the alternator, a little grinding to the SC housing, and some modification of the air duct. But it was clear to me that without my other modifications, it would have fit with just the pulley and a little wire re-routing. I still have the old Valeo 115 amp unit which I figure I'll send out for rebuilding some day when the other S52 needs one.

[lokijibber]

does worldpac sell to regular customers? i often see them selling to autoshops

Worldpac does offer counter service here in NJ, but good luck getting through. I often have a friend with a shop account call my orders in for me.

[rudyrov]

Any consensus of how many miles you can put on a standard Z3 6 cylinder alternator before you have brush failure?

[Mr Bingley]

Any consensus of how many miles you can put on a standard Z3 6 cylinder alternator before you have brush failure?

I think that would depend on too may variables--average RPM in those miles, average current draw, continuous operation or long periods of sitting, battery maintenance/replacement intervals, Valeo or Bosch--no two cars will be the same. Mine made it about 123,000 miles FWIW.

[rudyrov]

I think that would depend on too may variables--average RPM in those miles, average current draw, continuous operation or long periods of sitting, battery maintenance/replacement intervals, Valeo or Bosch--no two cars will be the same. Mine made it about 123,000 miles FWIW.

Thanks for that Mr. Bingley. My car has about 110k so far, kind of gives me an indication that I should start looking for one and maybe not wait. Wonder if anybody has located the brushes and just replaced them, I have done that to many a var and it works just fine mostly?

[BenFenner]

I wasn't sure if anecdotal data was what you were after, but it seems so?
Mine died at 140k miles.

If a shop can reman an alternator, there's probably no reason you couldn't do it too. (Mine crumbled to pieces when it was removed, so I went new.)

[moonvan]

I ran into this very same issue when I did my last swap. it wasnt difficult to re route teh wire but i did find it interesting that the alternators would be different considering its pretty much the same drivetrain.

[rf900rkw]

If you want random mileage polls, I have 143K, 172K, 223K and 244K with nary an alternator failure. S52 S52 M54 M52TU.

[bplease]

80k but it got rebuilt in a day for $100.

[Swaybars]

Brushes were worn on my car at 115k miles.

[gmushial]

This thread got me thinking/wondering just how unique alternators were to particular Z3's... so I check for mine on REALoem (12311432980), and then reversed that and looked for where that part number was used and it was a rather large collection of bimmers. Then I went to eBay to see what was available, and more interestingly, what would "also fit" and the list became even longer... so I'm wondering: if the S52 is basically a M52 block and a M54 head (very very roughly), if in fact there weren't "M52" alternators that would also mount up? Yes, wire length and orientation might be a question, though suspect most of the connectors more or less look the same? Part of the motivation is: as more and more ///M parts get NLA's on RealOEM, if there aren't other parts that might fit and do the job just as well? [Yes, clearly there those parts that are truly unique to the ///M's and can't be substituted... but in many ways, an alternator is an alternator, and given the right mountings and connectors should do the job.]

[rf900rkw]

The S52 is a pampered M52 block and head, with a M50 oil filter housing / alternator mount.

[gmushial]

The S52 is a pampered M52 block and head, with a M50 oil filter housing / alternator mount.

Thus being the case, and especially you, have you considered the case of swapping the alt mount to a M52 one and being able to use more off the shelf alternators? Or even using M50 alternators(*)... and yes, I understand that you haven't lost a S52 alt yet, so maybe you haven't had to cross this bridge... but just wondering....
as always: many thanks.

(*) I have a really excellent alt rebuild shop in town, so generally I go that route... but for most I believe such has ceased to be... and given the number of S52 Z's out there, and the price genuine ///M parts are fetching (and ever ratcheting upward), maybe high quality work-arounds might be the future?

[rf900rkw]

It's not an M50 oilfilter housing. It's an M50 - like housing that is unique to the S52. But no matter as the M50, M52, and non-Z S52 are all the same alternators.

I have local rebuild shops. If that were not possible, I would look into re-clocking the 140A M3 version and using the MZ3 cover.

[Mr Bingley]

It's not an M50 oilfilter housing. It's an M50 - like housing that is unique to the S52. But no matter as the M50, M52, and non-Z S52 are all the same alternators.

I have local rebuild shops. If that were not possible, I would look into re-clocking the 140A M3 version and using the MZ3 cover.

What is re-clocking?

[rf900rkw]

The alternator is a sandwich of several layers and housings. Typically they can be stacked and bolted together in multiple orientations. The M3 alternator has the rectifier pack with the B+ and D+ connections 90 or 180 degrees from the Z3M version. It *may* be popssible to restack the M3 in our orientation. Haven't tried, but I would look into that before modifying the wiring.

[gmushial]

Makes sense... had just never thought about trying such :-) ... though I suspect most of us have been sufficiently well trained by "life," ie, if you're going to take it apart, remember how it was, so that you can put it back together the same way, ie, the antithesis of considering putting it back together the "wrong way," intentionally... classic outside-of-the-box thinking :-)

[Mr Bingley]

What is re-clocking?

Ah, I see--as I recall there is an offset bolt pattern on the rear housing that prevented this approach. The wiring thing is just remove a tie down strap and re-route around a bracket--plenty of length and clearance and wire tie to the other side of the bracket.

[gmushial]

A sweet idea while it lasted :-( ... but in looking at the various alternator photos on eBay, although the clamping bolts that join the front and rear halves together seem to be at even 90deg separation, the two problems that I think I see are: 1) that the front and rear halves don't meet in a planar surface, but in fact in a notched/offset configuration, making it look like they'll only mate in one configuration, and 2) the mounting brackets are split btwn the front half and the rear half, meaning that if the rear half isn't in its nominal orientation, then one doesn't have a complete bracket for a thru bolt to work with. :-(

Which takes me back to the thought of, and implied by randyw, what about other alternators (ie, ones nominally for other applications)?

[rf900rkw]

Obviously the case halves have to remain in their relative positions. I'm talking about moving the guts relative to the case, shifting the windings and diode plate around to the Z3M position. Again, I don't know if it's possible without looking at one. The only alternator rebuild DIY I can find on the webs involves lifting the pulley and sliding a new alternator under it. Lots of pictures.

[Horrid Funk]

Resurrecting this info thread to contribute a little bit, as I was using this as a resource and figured someone else may end up here as well. I spun the terminal studs on my original alternator (Nuts seized after 20 years and 189,000 miles apparently) while trying to remove the alternator to replace the oil filter housing gasket. I ended up cutting the ring terminals from the wires and am going to crimp new ring terminals on. The plastic cover came apart into a few pieces as well.

From what I can tell, Bosch no longer offers AL9414X. The OEM BMW alternator P/N (12311405918) can still be found but it's more expensive. Cheapest I could find online was ~$500 with a ~$300 core deposit. I was considering trying to make the Bosch AL0739X alternator work, but decided to try a local alternator shop first. That was a good choice, thank you everyone who is recommending that in these threads. Alternator shop is going to completely rebuild the whole thing, except for the plastic cover, which we're going to try gluing back together. I was quoted $225, and it's only going to take a couple days. Some internal parts were apparently pretty worn out as well, so it was probably a good thing I damaged it now and had to take it in!

Lesson learned: Use a local alternator shop wherever possible. I'm using S&N Auto Electric in Sacramento and they seem very knowledgeable. Also, use anti-seize on the electrical connector nuts!