We took our 2007 ML350 into a non-dealer service center that specializes in imports for several service items to be completed: brakes, transmission flush, etc (totaling nearly $2,000). We keep this car in excellent physical and operational condition, and my wife (primary driver) is very careful on the road. After getting the car back, my wife noticed that when she applied the brake, there would often be a popping noise heard that seemed to come from somewhere under the passenger side of the hood. We took the car back to the service center to inspect. They are now telling us that the problem is an upper control arm that needs to be replaced on the passenger side. I thought it was odd that we didn't have this problem until we took the car to them the first time. They said that they did nothing with the suspension and therefore could not have caused the problem, and that it was likely a coincidence. Obviously, coincidences are always possible, but could this have been caused by someone carelessly lifting the vehicle and the suspension settling? They are saying that this is a common problem with Mercedes vehicles. Is that true? They are wanting to charge me $975 (inclusive of taxes and shop fees) to replace both upper control arms. Although only one is making a noise, they say the other one has some play in it and will inevitably start doing the same thing. Any and all thoughts would be greatly appreciated. Thanks in advance!

 

dont replace them. the MLs and GLs had issues with front suspension noises, i recommend taking it to a MB dealer you trust. have them check it out. could be a strut. very common. i highly doubt that the mechanic did anything to your car. i would drive it and see if the noise goes away. sometimes after having a car on a lift you can hear noises from suspension components.

 

Chassis, thanks for the response! Seeing that you are a certified MB Master, it is reassuring to know that you don't think they did anything to cause this problem. I have used this place in the past to service my BMW and have been satisfied with their level of expertise and care. However, we are all human and make mistakes, and I frankly just don't know enough about suspensions to know if this is a common problem in MB vehicles or one potentially caused by a mechanic's careless handling.

That said, this noise has been occurring without reduction or elimination now for the good part of a month and a half. I made my wife drive on it to see if it would go away, and it hasn't. In fact, if anything, it has only gotten worse. It doesn't sound or feel like it is making the vehicle unsafe, just an audible annoyance that can be heard both inside and outside of the vehicle when the break is applied.

I took my car to them last Friday, and have been calling each day to find out what they have found. Yesterday, when I made my original post, was the following Wednesday. So, they had the car for five full business days before being able to diagnose the exact problem. And I know that they were trying to diagnose the exact source the whole time and not just being lazy because I randomly showed up at the garage the other day and they were looking at the vehicle. The said that although they thought it was a control arm issue, they wanted to make sure. They were having trouble duplicating the sound when it was parked in their garage or on a lift, which makes sense given the fact that it usually occurs when the brake is applied after the car has been moving. Anyway, they apparently had to get some kind of remote monitoring or listening device from one of their other garages to diagnose the source, which they claim is the upper passenger side control arm.

So, at this point, my only other question is whether or not it would be a good idea to replace both upper control arms or just one. They said only one was making the noise, but that the other was showing signs of play, which they are saying is a hallmark of that one going bad. They said that it would be cheaper for me to just replace both of them now instead of one now and one later, because a vehicle alignment has to be done when they make changes or adjustments to the suspension like this. I am thinking that if they only have to replace one control arm, the charge would be around $500. For both, they are quoting me $975 all-in. For both control arms, I know this is a good price because the local Mercedes dealer is wanting to charge close to $1,300 for parts and labor for the same work. Your thoughts?

Thanks in advance!

 

Where is the play coming from the upper ball joint on the upper control arm? If there is play in the upper control arm ball joint then yes you should get it replaced. I'm not sure if your car falls into this. some years back the ml's had a recall for the upper control arm. they installed a plate where the upper control arm mounts to the body. there was also an issue with the lower control arm mounting points on the body. sometimes just snugging up nuts and bolts does help. Check the sway bar links also.

 

So, some feedback. I had the local imports garage that I have been using for a few years go ahead and replace the upper control arms on both sides. They charged me $975 to do this, which is a fair price compared to the dealer. I grilled them hard prior to authorizing the work about making sure this was the problem and that it needed to be done. They assured me that the upper control arms were bad, based on their application of a listening ear device. The work was completed the other day and my wife went to pick up the vehicle. She drove it around and the problem persisted without change. Garage decided that it might be the pads they installed a few months earlier -- defective product, especially since this only happens when the brake is applied. They replaced the pads this morning under warranty and believe they have the problem licked. My wife is going to inspect and pick up the car later today. They refunded the $975 for the control arms and apologized for the inconvenience, which I thought was very generous (and the right thing to do). Fingers crossed ...

 

Chassis, the upper control arm problems with MLs was 2002, ours is a 2007. I looked this up after you mentioned it. I took your advice and asked them to check and snug up the mounting points on the lower control arms. They said everything looked good. If replacing the pads this morning doesn't work, I will tell them to check the sway bars as you suggested. Again, this popping noise only occurs during initial braking activity, and it started right after we had taken the vehicle to this garage for several service items (including a full brake job). So, it makes sense to me that defective pads could be the culprit, although it never really sounded like it was coming from the wheels area. We'll see, but thanks for your continued help!

 

Hi guys,

Just following post to see what you have come up with. I have a 2002 C-240 6 speed with 96,000 miles on it. The car started making noise from the passenger side front end about a year ago. I replaced the struts with Bilstein struts, balanced and aligned the tires, and recently put new michelins on the car. The noise is only when you go over a bump, or uneven pavement. It sounds like it is bottoming out, but the car rides fine otherwise. My local shop did a wheel alignment on it a few months back, and said everything was tight. The sound is the exact same as it was before the new struts and tires, leading me to think it is control arms or something else. Any ideas on what this could be? I am open to any thoughts.

 

sway bar bushings and links are common for noise on that car. id replace them next. pretty cheap too.

 

Parts on order, install Friday. I will keep you posted.

Thanks