So we had a call early last week to say the car was finished and ready for collection BUT would I go to the dealers to drive the car to check the noise had been cured..... Strange request I thought!
So off to the dealers and within 5 minutes of driving the noise was exactly the same as before!!! So it wasnt the turbo as suspected!
Dealers very apologetic and will sort it ASAP but at the time had no idea what could be causing it. I took a senior technician out with me and he heard it as soon as I demonstrated it. He had no idea what it was be he heard it which helped.
They needed the 520 Touring back to sell as we had done just shy of 3,000 miles in it and it was a demo car so they gave us a brand new X3 2.0D M-Sport in replacement which was nice.
Had a call on Monday saying that they had rigged up various microphones around the car and the only noise was from the front diff! A new diff was ordered and I awaited the call. At 10am this morning our X5 pulled up outside work with a BMW technician smiling asking for me to drive the car again as the noise had been cured! And it was gone which is a result! It appears the noise was some play in the front diff which was only evident under load at the RPM range as that is when maximum torque is produced. So driven gently off-boost it wouldn't happen as not being put under full torque load. The technician seemed very happy indeed as he had been lying in bed thinking about what could have been causing the noise and finally he found the fault and cure.
So back to the dealers the car went to be finished off, valeted and hopefully back in our care tomorrow!
All good fun especially whilst under warranty
Chris