Luis Borrageiro

Hi Guys please advise or help if you can, my ML is on 165000 Km (103125 miles) and just out of the extended maintenance, it has started to make a strange noise from pull off especially if you floor the vehicle, and its coming from the front to middle of the car, and its a rotating knocking noise. I have checked the prop shaft's both front and back, all four wheels for any loose bolts or brackets, but cant find anything, what i did find is that there is a little extra play from the transfer box to the front prop shaft and that it makes a clink sound when u turn it by hand. could the problem be in the transfer box and is it a common problem, no lights come up on the dash when it makes the noise and the car still drives fine with no vibration. This is the first and only problem i have with this car since new.