Anyone Have a Bad Alternator on a 4.8? Symptons

macmac80210 · #1 07-11-2016, 02:39 PM

Car was in the shop this week and they did upper and lower coolant hoses. Picked it up, driving it home heard this awful whirr / whine from the engine.

Brought it back the next day, now they said it's a failing alternator bearing?

Anyone do their alternator on a 4.8? From the shop manual I've seen it doesn't have to take much work to get it replaced, maybe a few hours?

Is there any conclusion about using an OEM or OE part? New or remanufactured?

OE is a Valeo 220amp, but Bosch and a couple others make these as well.

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X5Boise · #2 07-12-2016, 09:35 AM

My 35d makes the same whine noise (engine speed dependent, regardless if in N or Drive). My independent diagnosed as a bad alternator bearing as well. I ordered a new Valeo 220A (since I have 4 zone climate control) from AutohausAZ.com for $475 shipped during a 4th July sale (no core required). I would be inclined to try Bosch, but for now, I stuck with the OE Valeo for now. The shop will be charging me about 2hrs for the install--it doesn't look too bad for a DIY job though.

macmac80210 · #3 07-13-2016, 01:58 PM

Yep, just got it back. Was indeed the alternator bearing.

I had the indy pull out the alternator, took it to a rebuild shop, they swapped the bearings (both front and back for $90) and the indy got it back in, same day.

Total cost: $225.
Quoted cost for new alternator + install from another indy: $1,565.

Good deal.

X5Boise · #4 07-15-2016, 12:29 AM

Just picked up the X5 35d from the shop. No more engine-speed dependent whine with the new Valeo 220A alternator. Too bad I wasn't offered the rebuild option as your shop offered ($475 new alternator plus $200 labor). The old alternator seemed to have a little "looseness" to one bearing when I manually spun it when it was removed from the car.

gregg3gs · #5 07-15-2016, 06:38 PM

I did my alternator when I hit about 100K on the car.
Parts $850
Labor $free (self installed)

Easy job but requires a good bit of parts taken out.

Here is one of my DIY's you can use to get to the point where you remove the serpentine belt. Afterwards it's a tight fit but it all works.
http://www.xoutpost.com/bmw-sav-foru...-n62-4-8l.html

ika · #6 07-17-2016, 02:04 AM

I had whine noise from alternator, but replacing bearings didn't help. Than i replaced voltage regulator and whine noise has gone.

Davidf · #7 07-20-2016, 01:48 PM

I just replaced the alternator on my '08 4.8i. Symptoms were:
1. Occasional bearing type noise. Stop engine, restart and noise went away.
2. Occasional dead battery and engine stop while driving.

The failure mode was sporadic. Most of the time, it worked fine. But, when it did not, I ended up stranded. Rebuilt (OE) unit from Auto Zone solved the problem.

Normally, I have alternators rebuilt rather than replace, but time was short as I needed to go on a 1200 mile road trip. So, replacement made the most sense. I also suspect the voltage regulator (noise and no sporadic no charge condition) as the bearings felt fine when spinning by hand.

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