Hi Steve, I have just bought a second hand (08) BMW 118d SE 143 3 door on 39000 miles. On the way home from Dealer the following happened and continues to happen. Immediately when the rev counter falls below the 1 mark there is a knocking sound which appears to be coming from the dashboard. It stops IMMEDIATELY when rev counter goes above 1. It is almost as if there is something loose inside the dash however I doubt this is the cause as the noise starts/stops so precisely when rev counter is below/above 1. The noise can hardly be heard outside car with engine running and bonnet up. It can only be heard inside the car. It happens regardless of whether car is in gear or neutral. Can you suggest anything? Regards, XXXXX XXXXX
I have also just noticed that it does not start immediately. It seems to happen once the car has been running for a time.
Very many thanks for this. I subsequently added a note saying the noise did not start immediately but once the engine had been running for a time and has had time to heat up. Do you think this is relevent and based on this is there anything you would add to your answer.
Also when you say 'mechanical knowing', did you mean mechanical knocking?
On the face of it I would describe it more as a clicking sound, although my wife reckons it sounds more like knocking. If what you say is the case regarding electrical circuits working overtime how can I rectify this. Thanks again.
Regards, XXXXX XXXXX