I have a 320ci petrol on a 59 plate, I have a noise coming from under the bonnet which is starting to annoy me and I am worried something more serious is going to come of it.
The noise occurs normally when I have first turned on the car, (sometimes it struggles to start - can take about 4 - 5 seconds to start) if I am driving in 2nd or 3rd and get to about 3000 / 3500 rpm and let go of the accelerator there will be a loud blowing / rubbing noise coming from under the bonnet, if I then accelerate the noise disappears until I let go of the accelerator again. It almost sounds like an engine revving problem but I really don't know.
I have taken it into the BMW dealership where I purchased the car and they told me nothing is wrong with the car, I also took it to a local mechanic and he gave it a once over and said he cannot see anything wrong with the engine etc.
BMW recently changed the water pump and the starter plugs under warranty, not sure if this could have anything to do with it??
I understand this explanation might not be the best but I hope someone can help.
Thanks - Will