sleder700trp

I have a 2000 ML55 that has a loud humming noise coming from underneath the mid to front section of the car. The noise is directly related to speed. (the faster I go the louder it gets.) When you turn the noise will go away. I thought it was the left front wheel bearing at first so I changed it but noise is still there. Then I thought it might be the front drive shaft that runs from the transfer case to the front differential so I changed the u joints and center bearing but the noise still exists. I would hate to change the entire driveline to fix this problem. Wondering if anyone has had similar problems with their ML. I know for a fact that the tires are not the problem. Any help would be greatly appreciated.


Thanks,
Christian

Maj. Dundee

Noises are very difficult to diagnose without actually hearing it. My suggestion is to put the truck on an alignment rack where the four wheels can be supported. Then the truck can be run and the noise can be isolated using a mechanic's stethoscope.

sleder700trp

I was thinking that would be the only way. I tried that on a regular frame lift but the noise isn't there unless the wheels are supported

Maj. Dundee

In the future don't do what you have done. Damage could arise and set codes which you will have to have scanned out.

Also try and stay with the truck as it is being done so you can verify where the noise is coming from.

sleder700trp

I plan on changing the right front wheel bearing and the center support bearing this weekend. if that doesn't solve the problem I will have to put on alignment lift

Maj. Dundee

You said that you already did these things in your first post.

sleder700trp

I changed the left front wheel bearing and u joints, not the right front wheel bearing. Center support bearing is behind the transfer case

Maj. Dundee

The front driveshaft only has a double Cardan joint/u-joint but not a center bearing which is only on the main driveshaft.

"so I changed the u joints and center bearing but the noise still exists."

sleder700trp

I changed the left front wheel bearing and the the double cardin u joint for the front drive shaft. I was planning on changing the right front wheel bearing and centering bearing that goes on the main drive shaft this weekend. Noise only goes away when making a left hand turn. The wheel bearing was only 25 bucks and the center bearing was only 50 so not too expensive since i will do it myself. I dought it wold be the transfer case because if it were the transfer case the noise should be constant and not go away when turning left.