[rjahl]

OK, I don't normally post engine problems on this site but I need a little help with this one.

Last month, I isolated a noise from the front of the motor as coming from the alternator. 170,000+ miles, i figured it was time to order a replacement. Belt and tensioner are fairly new. Picked up a rebuild unit from a name brand auto parts store and did the swap, pretty much no drama. Except, I now had a completely new noise. The new alternator had a horrible electrical whine. I put up with it for a few weeks before demanding a replacement. I just installed the replacement and it has marginally less whine, but it's still there. To make matters worse, I've started to have other problems, Oil level sensor failed and while digging around looking for the problem, INPA told me I had lost communications with the electric water pump. WTF...

Major error was 2E7C Bit serial data ,

I guess the Water pump, alternator and oil sensor share the same communication channel.

After digging around under the hood for too long, even swapped out a spare DME, I went back to the beginning and disconnected the new alternator. Bingo, everything started to work again. Codes cleared and stayed cleared except for the error telling me the alternator communications were lost.

So back at the auto parts store I was simply just offered a third alternator . I discussed simply cancelling the order but my original core has been shipped off for recycling.

Anyone had any similar experiences or advice?

BTW, I can make the whine go away by controlling the alternator output through INPA. Drop the voltage set point to 12 volts the dam thing is silent.

[twastheglow]

I'm assuming this wasn't an OEM replacement. Also, although not on my BMWs, I've never had good luck with rebuilt starters or alternators. Because of that, I've always replaced those parts with new OEM units on my bimmers.

[twastheglow]

With that being said, is it maybe the voltage regulator on your replacement unit(s) isn't as precise and exact as what it needs to be to prevent issue?

[rjahl]

Originally Posted by twastheglow

With that being said, is it maybe the voltage regulator on your replacement unit(s) isn't as precise and exact as what it needs to be to prevent issue?

Actually I'm thinking they skimped on the windings and the voltage regulator is pushing the exciter windings really hard.

I'm wondering if anyone else has had similar issues or experiences?

The data interruption has me miffed, I hope this is not a symptom of some other electrical issue.

I checked the bonding strip today and that appeared ok.

[twastheglow]

Originally Posted by rjahl

Actually I'm thinking they skimped on the windings and the voltage regulator is pushing the exciter windings really hard.

I'm wondering if anyone else has had similar issues or experiences?

The data interruption has me miffed, I hope this is not a symptom of some other electrical issue.

I checked the bonding strip today and that appeared ok.

As a cost-saving measure, that could very well be the case. Sucks your core is long gone, but at this point I'd strongly consider trying to get your money back and picking up an OEM unit. My guess is that'll fix your issue.

[PhaseP]

They don't touch the windings during rebuild. I had rebuilt my alternator with a kit and very good instruction video from builder, so have some knowledge. The slip rings, brushes, front and rear bearings are supposed to be replaced, that is all.
But also they may have replaced the pulley, especially on these the pulley is overriding one and is subject to wear. I think a good rebuild should replace the pulley for that reason. You can test the pulley by blocking the alternator somehow (sticking a screw drive in at a point windings or anything else will not be damaged) and pulley should turn one way easily, and not at all at the other direction. Like bicycle hub brake.

It is possible the windings might have been moved/gotten loose during disassembly especially to get the bearings out if they pushed on the windings. Dislodged windings can I suppose make noise.

The voltage regulator also may have problem and causing noise too. In your last case it did have problem with the BSD error. As you guessed they are all on the same BSD bus.

[PhaseP]

Also if it comes to it, I believe the voltage regulator is available separately, you can check realoem.com

[rjahl]

Originally Posted by PhaseP

Also if it comes to it, I believe the voltage regulator is available separately, you can check realoem.com

Yes, the pulleys looked and seems to function correctly. The one way clutch grabbed without making any noise.

I guess you are correct about the windings. It's probably not very cost effective on these small alternators.

Rebuilding these alternators should not be that hard. I would expect a popular parts store would get that correct. They can't afford to continuously supply faulty parts.

I can't help but worry that I'm missing something.

[twastheglow]

I'm still putting my money on the alternator as a whole being the problem. My guess is an OEM unit will perform normally. I haven't priced a new one, but if it's more than you wanted to "gamble", maybe take the plunge and invest in the time it takes to swap out a known properly working unit out of a friend/local forum members car. Just a thought.

[dstrickland]

Have you checked into the IBS? Usually bit serial data codes relate to IBS codes(clear your codes, unplug IBS & see if the same code comes up).

Maybe your alternator is getting incorrect request & working overtime?

[rjahl]

Originally Posted by dstrickland

Have you checked into the IBS? Usually bit serial data codes relate to IBS codes(clear your codes, unplug IBS & see if the same code comes up).

Maybe your alternator is getting incorrect request & working overtime?

When I unplugged the alternator the IBS related codes could be cleared. All stay cleared but a new one pops up related to the lost communication to the alternator. LOL

Is the another point / jack that I can test?

[dstrickland]

Originally Posted by rjahl

When I unplugged the alternator the IBS related codes could be cleared. All stay cleared but a new one pops up related to the lost communication to the alternator. LOL

Is the another point / jack that I can test?

You can test the IBS connector directly. I forgot the acceptable thresholds, but ISTA will help you out there.

Clear your codes, unplug the IBS from the negative terminal on your battery & crank your car. This will throw the IBS code in the DME so Ista will pick it up & put it in your test plan. Before you begin the test plan plug the IBS in & complete the test plan with ISTA.

I've seen the IBS cause insane issues depending on the model...just got through getting an e64 M6 up & rolling. IBS was keeping it from going into position 2, no cluster, nothing...from what your describing, it's the only thing that's linking your sound, your codes & your symptoms together.

[rjahl]

Took a gamble this morning and tried alternator number three. This one looked like a new unit. Spotless and had no signs of a past like at all.

Swapped in the new alternator. Took less than an hour as the serpentine belt behaved itself this morning. I guess the practice helped.

Like Magic , no codes and full control of the water pump. Oil sender is working as well.

It's still a little noisy at idle but it's probably the quietest of the bunch. I would not hear it if I had headers or a sport exhaust.

[twastheglow]

Glad to hear it's mostly sorted.