Hi,

First post here. Please feel free to redirect to another sub-forum if this is in the wrong place.

I have a 2015 ML250 BlueTec with 155,000 miles on it. We love it, and have taken it from coast-to-coast, and north to south.

The car has developed a creaking/squishing sound out of the right front; it sort of sounds like a creaking mattress. If I bounce on the running board on that side, I can elicit the sound. I hear it (always!) at low speeds, but ambient noise covers it up at higher speeds.

I took it into my non-Mercedes service shop, and they recommended replacing the struts, and, as long as I'm doing that, replacing the shocks. I double-checked with a local tire/suspension shop, and they quoted me for the work. It is, of course, on the more expensive side.

I couldn't make a decision, so I'm going to make the big schlep into Raleigh to have the MB Service Dept take a look, charging $219 just for the privilege of putting it on the lift. When I set up the appointment, the service rep thought it was strange that I would be interested in the work, and that struts and shocks really don't need to be replaced. Like... ever, in most cases, according to her.

Okay, now I'm confused. Even ChatGpT told me to get it done. At this mileage, should I be thinking about getting the full treatment, or just addressing the squish on the right front? I don't mind spending the bucks if it makes sense.

I will say that over the past couple of years, I feel that the ride just isn't what it used to be, and I imagine it would be a lot smoother with new suspension bits. This makes sense -- I've driven on I-95 through South Carolina a lot, and have taken quite a few shots due to the bad roads there. Oh, and Maine, too.

Alignment and balance is good, tire wear is even. I could live with the ride as it is, but can it be better?

Warning: I'm not a car guy. Just a happy ML250 owner.

Thanks,
Rob

 

Welcome! You are in the right forum.

There are no struts on a W166 but rather shocks. Shocks are often erroneously referred to as struts.

Bouncing on the running board test is meaningless. All suspensions make noise under that condition.

Do you have air suspension? What you describe is possibly a worn air spring. Again often incorrectly referred to as a strut.

Creaking can symptomatic of a worn stabilizer bar bushing or one of the suspension joints (stabilizer link, tie rod, upper or lower ball joint.

All cars at 155k miles ride worse than when they were younger. Everything rubber (bushings) deteriorates. Your even tire wear suggests shocks are not bad and ball joints and tie rods are not bad.

Ask the MB dealer to focus on stabilizer bushings and stabilizer links in addition to their evaluation of the main suspension components (springs, shocks, joints, bushings). The preceding sentence is a standard suspension assessment and should not be extra cost beyond the diag fee they are charging you.


Don’t be surprised if they recommend a long expensive list of repairs. They envision big dollars flowing out of your pocket and into theirs with a 155k mile car.

 

Thanks for the great information, Chassis.

I will admit that I don't know what the W166 designator is, but I'm glad I landed in the right forum.

I find it's curious that my local shop mentioned struts and distinguished them from rear shocks. Now I wonder if that's just 'southern terminology', or a cranio-rectal inversion.

Although my at-home bounce test is meaningless, I do note that if I bounce any of the other quadrants, there is no noise. Only the right front, and it sure does make a lot of noise.

Based on that noise, and with your information and cautions, I'll take it to the dealership on Monday. I guess if they come back with a long list, I can whittle it down to what might be essential... not like I'd know.

Rob

 

There are more moving parts on the front suspension than just the springs and shocks. Any of the control arm bushings could be making noise.

To your question, the time to replace the shock is when it is visibly leaking. Coincidentally, I just replaced both my rear shocks on my airmatic ML this morning. Might do the air bags next week. The Bilstein kit (2 shocks, 2 air springs) was about $1800 IIRC, only a few hundred dollars over what the dealer wanted to replace the single leaking (rear passenger side) shock. The job wasn't hard, but taking the rear interior half of the car apart (side panels, seat backs, everything down to sheet metal) to get to the 2 screws on top of each shock was a PITA. Easy but time consuming.

 

The erroneous use of strut is common with "coilovers" which you have in the front suspension. This means the coil spring is installed "over" the shock. Strut nevertheless remains a misnomer. Your rear suspension has separately mounted shocks and springs.

Do you have air suspension?

With the new information that you did the bounce test on all four corners, this indicates "something is up" in the corner making noise.

Please report back on the dealer's diagnosis.

 

How can I tell? (Note the Newbie tag next to my handle.)

Will do! I appreciate the help.

Rob

 

enter your VIN here to get your datacard which lists all the options on your vehicle: https://www.lastvin.com/

 

I did that last night and pored over the list, but couldn't find anything I recognized as being obviously related to shocks.

Can you tell me what tag or entry to look for?

[Edit: I looked at LastVIN again. Although it's clearly my MB, I just can't recognize anything related to what type of shocks I have. The closest I see is "V59 SPEED- + LOADINDEX 107H XL", and "VL FRONT AXLE HALF, LEFT" with a corresponding entry for Right.]

Thanks!

 

Look for something like the below in your results from lastvin. Or post your VIN here and others can definitively tell you.

The below is a lastvin report from a 2014 ML63, same platform as your vehicle but different trim level. Air suspension was available from the factory on your car.

 

Just for cost reference, I replaced a leaking rear strut on my Airmatic W166 (sorry Chassis, the assembly looks like a strut to me, attaches to the strut tower body mount on top, and the lower suspension arm at the bottom...integral unit, not just the dampening part), was quoted US$1800 by 2 different dealerships, purchased a genuine MB unit online from a dealer for US$350 including shipping, and took me maybe 90 minutes to do the swap out (getting the adaptive dampening electric plug off to strut without breaking was the hardest part). Ultimately, it is only attached by 2 or 3 nuts on the top, and one large bolt at the bottom. Saved US$1,450 on just ONE. Nicknamed "Stealerships" for a reason.

 

I still don't see it. Should I assume, then, that it is not air suspension?

The VIN is: 4JGDA0EB8FA469411

[Edit: Well, that's interesting. After posting the above VIN, the forum turned it into a hyperlink. Following that, I see the front is a double-wishbone suspension.]

 

You're fortunate to be able to do the work yourself, saving a lot of money.

There is simply no chance that I'd be able to do this myself. No, sir-ee, no chance whatsoever.

 

If you have Airmatic, the front suspension looks like this.
If you don't, the black rubber part at the top is replaced with a black coil spring, like this.

I agree with other posters. A bad shock/strut would make more of a clunking or rattle noise than a squeak, if it made noise at all. The piston dampers wear out, and the rod just flops around inside the housing without pressure. A squeak sounds more like a rubber bushing on your suspension to me too.

 

This is probably "good" news.

I took a look underneath. Looks like coil shocks to me. No air suspension.

Next, I had my wife bounce on the running board to see if I could isolate the sound. In the picture of the front suspension below, there is a large rubber piece at the apex of the wishbone. To me, it seems that the sound is coming from there, but it's hard to tell. Susan said that it might be at the legs of the wishbone.

It seems that things are in pretty good shape; nothing heinous to my eye. And hopefully it's just a minor repair.

Any thoughts on this?

 

Take a can of silicone spray with the straw attached, and spray some in at the bushings at the 2 inner attachment points (not the ball joint boot). Bounce it a few times to work it in and see if that helps.

 

Dont use petrolium products like WD40...can deteriorate the rubber. Use silicone spray. I get at Home Depot.

 

Thanks. I'll give it a shot, as it were. Off to find some spray. Even though I've been called "lube savvy", it's the one lubricant that I don't have in the shop.

Will report back...

 

@Leetom , I got the spray and hit those points pretty well while at the auto parts shop. I thought it calmed things down, but after getting home and fairly slathering those two spots again -- on both left and right front -- the noise is still there. Maybe just a touch quieter, but still quite there.

To be clear, as I'm looking at the pictures above, there is a large, single, double-lipped boot sort of rubber thing at the head of the wishbone, and rubber parts on the left and right of each of the two attachment points that are inboard. I hit both of the two attachment points.

Is that correct? And I'm not to hit the large double-lipped boot? It seemed to me that this boot is where the sound is coming from.

I'm torn at this point. I'd love to avoid the dealership, if possible, but as I'm sensitive to noises, this will drive me nuts if I don't fix it or have it fixed. We audiophiles are a touchy lot.

 

@RobH739

You do not have air suspension. This is confirmed both by the photo you posted and the VIN, thanks for providing it.

The "wishbone" item you are evaluating is the upper control arm. The "inner two legs" which you lubed contain rubber pivot bushings. The double-lipped item is the upper ball joint. It is not unheard of for upper control arms to go bad; they are wear items. The dealer will know if this is the source of your issues. My gut is telling my that the stabilizer bar bushings or links might be the problem, but I am not there to see/hear and the dealer will identify this for you.

 

No apologies needed. Appearing to be a strut, and being a strut are nevertheless not the same. A strut is used on MacPherson-type suspensions. A strut provides kinematic function to the suspension and reacts both forces and moments. Coilovers, or spring-shock modules as you have in your Airmatic suspension, are not struts. They are coilovers or spring-shock modules or assemblies. A strut is, well, a strut.

A coilover, consisting of a spring and shock, does not provide kinematic function. It does not react (overturning) moments from the wheel. A coilover is therefore not a strut.

For Airmatic, "coilover" can be used from a functional equivalency point of view. If one likes, airbag-shock module is another label that can be used. People with expensive German cars often don't like to use the word "airbag" or "bags" because of negative connotations with aftermarket and street culture, or with commercial vehicles. Airbags, however, are indeed installed in Mercedes, Porsches, BMWs, Bentleys, Rolls Royces and any other car with air suspension. The airbag is simply a basic rubber bladder. That's all.

First image: Porsche 991 front MacPherson strut suspension. Note the strut is joined to the knuckle (wheel carrier, hub carrier) with two brackets or clamps. The spring is mounted to the strut. A strut delivers a kinematic function and reacts both forces and (overturning) moments.

Second image: Porsche 991 front suspension diagram from a Porsche dealer parts shopping platform.

Third image: Porsche 991 front suspension strut from the same parts shopping platform.

 

Well, based on your input we've decided to do the dealership. Too bad... I thought that if the silicone fixed the issue, we'd cancel the appointment and get a ride in on the local trails. I guess I'll be adulting tomorrow, instead.

My sense is that something has gone bad, and I'd rather deal with it now than on a long road trip.

This car has been pretty reliable, with the exception of a pretty bad coolant leak and a mysterious sudden-lack-of-acceleration issue that would come and go. Fortunately, neither has happened in quite some time, so I think those issues have been addressed.

 

As said above, the front folded boot is the upper ball joint. I dont believe there is any grease zerk on these to inject grease inside to the ball joint. Spraying the boot wont do anything for your squeek. If it IS the joint, it would need to be pressed out and new one pressed in. As Chassis said, may need to get a mechanic in there to pin down the squeek to figure out next move. If sway bar bushings, they are not terribly hard to replace.

 

I know what you mean about I-95 in SC. It is recent concrete paving but has huge collapsed holes in it that will break a suspension if you hit them.

 

They've recently paved a lot of I-95 in SC, although there are still some nasty sections such as around Santee.

Used to be that as you went north from Georgia into SC, just as the bridge over the Savannah River ended at the state line, WHAM! And it was unavoidable. Fortunately, they've fixed that one.

 

Update:

The car was inducted at Mercedes Raleigh on Monday. I got an evaluation by the end of the day.

Front right strut was worn, which was the source of the noise. They recommended replacing the struts as a pair, although they gave me an option for just the one.

Rear suspension looks to be in good shape, although based on age they recommended new rear shocks.

Tire and brake wear are good and even.

They found a bit of an oil leak around the throttle valve actuator, where an air line goes in. The leak seems to have been there a while. They recommended replacing the O-rings.

All in all, for a 2015 with 156K, they said it was in really good shape, and thanked me for that. That made me feel good. Very good, indeed. A feeling that was diminished when I got the estimate.

The vehicle is being held hostage until Friday, but I got an MLB 250 loaner. We know things in contrast; I'll be delighted to get my 'real' car back.

Thanks, everyone, for your advice and help!