Anyone that has had an alterantor go bad on their bmw

[Crowz]

This isn't about an X5 aka E53 but instead is about my daughters 1997 528i aka E39. Since our X5's share a ton with the E39 I was wondering if our X5's could do this.

My daughter called me today saying the car was acting strange.

She was leaving out to go shopping and at first the car turned off the headlights.

Then a bit further the radio.

Then as she was almost home the dash lights.

Then everything else but the motor right before she got home.

She made it home safely. Basically the car was turning off things to keep running to get her home. AMAZED.

I have never had an alternator go bad on a bmw so I am wondering which models can do this. Any ideas?

[14thbmw]

I’ve had alternators go bad on BMWs going back to a 1974 2002tii (several times), so that is nothing new. The part about stuff not working somewhat progressively is definitely on our e53 X5 and newer ones. Not sure how far back that “feature” goes. I think it is annoying, because it makes it very hard to diagnose, say, a seat heater that seems to suddenly stop working or only work after driving 5 miles or so. But I can see how it gave you some comfort in this situation.

[BigBody]

Mine started to get lazy in the morning during the cold, with the gen light turning on. Also if I idle too long, while working on something the systems will start to fail and ill get a flashing Christmas tree on the dash until I start driving the engine, and the voltage gets back to normal. If I turn the car off during the flashing abs, brake, etc warning phase, the car won't start up again because the battery is too low, and will need to be jumped. Pretty sure its just old, and starting to kick the bucket. If its driven, no problems, it just appears to not produce enough energy on idle anymore. With that being said, I can't say Ill be surprised if my alternator craps out sometime soon...

[andrewwynn]

See if the E39 will let you use the hidden menu like E53 to verify realtime voltage.

A single dip below 12v will put E53 into a minor version of limp home mode (many things disabled but engine performance still ok).

If the voltage is dropping as described your alternator Already has failed.

Usually the cause is dirty or worn slip rings or brushes. I'd you have the Valeo model there is a slip ring kit for $20 that is about 6/10 difficult and takes maybe 60-90 minutes to perform (on alternator already removed from the car off course)


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[Crowz]

Originally Posted by andrewwynn

See if the E39 will let you use the hidden menu like E53 to verify realtime voltage.

A single dip below 12v will put E53 into a minor version of limp home mode (many things disabled but engine performance still ok).

If the voltage is dropping as described your alternator Already has failed.

Usually the cause is dirty or worn slip rings or brushes. I'd you have the Valeo model there is a slip ring kit for $20 that is about 6/10 difficult and takes maybe 60-90 minutes to perform (on alternator already removed from the car off course)


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It wouldn't crank when she got back home so that's not a minor dip in voltage

The alternator is 21 years old and has 240k miles on it. Its the factory alternator. I think it deserves a new one not a rebuild at that point.

It earned its rest

[andrewwynn]

Won't disagree other than to say they are insanely robust and that there are only three things that ever wear on alternators: brushes, slip rings and bearings. $300-400 for an alternator or $50-60 to reset the clock back 150,000 miles since the electrical and electronics could easily last 1000000 miles


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[The Bigfella]

This year, I had two go - I repaired the alternator on my E34 M5 with a kit and replaced it on the E53 X5 with a new one sourced from fleabay.

[Crowz]

Its a bosch 120amp.

I may rebuild it as a spare for her. But considering its the only way she has to get around and she is going thru a divorce right now I need to get it going fast.

[snik]

I'm on my 3rd alternator in my E46 M3. The 2nd one was short lived as it pretty sure I spilled some kind cleaning solvent on it and a week later it shit the bed.
Contrary to popular believe the new LOT remanufactured ones from carquest work just fine.


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[StephenVA]

Easy fix