X5 E70 Alternator issues

[jamesw6810]

Hi all,

Ive had a looong search around for something specific to no avail - heres my issue:

Ive had the X5 for 2 years with no trouble whatsoever, but in the last 4 weeks it all seems to be falling to pieces. Ive done:

- Glow plug relay & plugs
- Both thermostats
- New AGM battery (and recoded)

This cleared issues with DPF regeneration and glow plug codes on all 6 cylinders, alongside some BCM comms errors

Now, the battery was changed due to the "Increased battery discharge" warning alongside poor voltage on shutdown of 11.4v. During this test phase i checked voltage at idle at its high at 14.9v, both tested at the alternator and the on board hidden menu, also verified through the Carly App

All codes have now disappeared, voltage is good on shutdown and the battery discharge error has gone. What im left with is:

- High 14.9v voltage at idle
- A whine when accelerating, more obvious in low revs
- A whine coming from the alternator area on idle & rpm at 2000

Ive ruled out the Power steering pump, fluid was a little low but flushed and topped to max, whine is still there

Through a bit of an arduous process of elimination i believe the noise is alternator related and co-incides with a large voltage output, so simply my question is - Any further thoughts on the voltage at 14.9v and the noise, can they be related or is it 2 separate issues (regulator and something else maybe)

Your expertise would be much appreciated

Many thanks in advance

James

[snrbrtsn]

Was the battery coded when replaced, possible a bearing in the alternator or idler pulley...
A spray of Wd40 (with the long stray) will identify cause, it may be worth checking the serpentine belt also in case it’s cracking and breaking up

[X5Sport]

14.9V is about the right peak voltage for an AGM type - which you say you have.

Non AGM (wet/gel) should be around 14.4V max.

[jamesw6810]

Thanks - if the voltage is correct then that narrows down to the noise only then, appreciate that

[Horizon]

The alternator pulleys on BMW's are a free wheel clutch type, I have changed mine on the E93 3 series as it was clicking like a bearing noise, but can also squeal .
The pulley/ freewheel was only about £12
At be worth googling , to see if it has the same symptoms as yours.
I had to buy a splined tool to swap them over £6 ish.