E70 4.8 pump noise when stationary
My 08 4.8 X5 is making a strange pump like whirring sound after driving and then coming to a stop at traffic or lights etc. once you take off it stops. It sounds like a pump or similar sound. Not linked to engine rpm. I noticed if you turn off the AC while it's making the noise it will stop. So may be related to that, but what could it be that it's switching on at low rpm or stopped speeds? Any ideas?
Is there some engine vacuum pump or similar?
I have the service manual DVD but its so hard to learn about the car, more a reference of u already know what's there.
Thanks
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