I have the strangest problem when backing up a steep driveway, which is perpendicular to the street. Ordinarily, I pull up to the curb just past the driveway, put the car in reverse, and then crank the steering wheel all the way to the right and begin backing up. At the point when the back end of my car (1994 E420) is on the driveway while the front end is still in the street, about the point where the front end is close to bottoming out on the street, the car makes a loud grinding sound, as if a fan of some sort is hitting something. I also noticed that if I straighten the steering wheel out at the point that it is making the noise, the noise does NOT go away. So it seems as though the noise only occurs when the front end of the car is very low to the ground.

My mechanic has been unable to duplicate this problem thus far, and I am hoping to get some suggestions from the forum as to what it might be. I'll be taking the car back first thing Monday morning, so if you have any ideas, please let me know. Many thanks in advance.

Maybe it is the fan hitting the shroud. Could your motor mounts be worn?

__________________
Bob Johnston
03 E55
Comand/Nav/Bluetooth/Ipod added
Black/black
(Oh man, this car is sooooo fast.)

My car has not been lowered at all. I did consider that the fan might be striking something in the car, and thought that maybe it might be the shocks, but that would not explain the sound. My car is in the shop right now for a fairly major repair (wiring harness, throttle valve actuator). I'll have him look at the engine mounts to see if they are worn out. At this point, I told him to simply keep the car as long as it takes to get everything right. They gave me a 300E as a loaner, so I don't really care how long it takes.

Thanks for the suggestions. If anyone comes up with something else, I'll be happy to pass them along to my mechanic.

Turns out the problem was a bad motor mount. When in the downhill position, the engine was shifting forward to the point that something was rubbing. New mount in place, no more problem!