Turn Left-No Noise, Go Straight-Lots O' Noise
 

I believe this is an easy question to answer. I think a rear wheel bearing (on my 2000 CLK430 Conv w/ 117k miles) is going out. There's a terribly loud noise while driving and it's coming from the back.

I've replaced all 4 tires and changed the diff fluid.

When I turn left, the noise goes away. When I turn right or go forward, the noise is still there.

Would this indicate a bad left or right rear wheel bearing?? :confused:

Thanks!

It sounds like the left side, assuming it is a bad bearing, because you load the outside wheel on the turn. I can't think of any other culprit - what kind of noise? Mine was a growling drone, like the engines on a 4-engine propeller plane.
A good shop should have chassis ears (remote microphones) to verify the side.

Based on the info provided, I agree a faulty rear wheel bearing is the issue. A good mechanic should be able to confirm.

There's a pretty easy way to track down the noise but it takes some caution on your part.

Chock the front wheels. Use a floor jack to lift the left wheel off the ground. Have a friend start the car and put the transmission in "drive". Put your hand on the bumper and feel for a vibration or grinding feel. Observe the wheel for "in and out" movement at the same time. Stop the car and do the same thing on the other side to eliminate any differential "noise" due to the different angles of the independant suspension. Don't do this if you have a "positrack" differential which you dont.

You can have your friend gently press on the gas pedal to about 30 mph on the speedo but don't go any faster.

Do this outside and the car pointed AWAY from your garage/house just in case your friend does something silly. In fact, point the car at their car just to keep them alert!:rolleyes:

I think ESP will kick in and lead to damage and havoc. Make sure the switch is "OFF" for this.

Thanks for mentioning this! One of the problems with giving service advice on the forum is there are always certain steps which you automatically do and you forget the person you are telling doesn't know them.

Sound is correct
 

Yes, it sounds just like an airplane! It's so loud that I can barely hear the radio now. I've ordered another bearing and I hope I can put it on. I've put bearings on other cars, but Mercedes are a different breed.

Do I need to get it "hydraulicly" pressed in or can I turn the wheel bearing puller around to pull it back thru??

I appreciate all the help!

So what was the outcome? I have the same symptoms.