2013 ML550 W166, purchased new, no wrecks, does NOT have active lane keeping. Car is wandering down highway like being hit by crosswinds. If I hit a patch of ice with 2 wheels while driving straight at highway speed, car suddenly jumps to opposide side that ice was on. Car has 58k miles, and Ive just replaced rear brakes 3rd time, still on original set of fronts...front pads still look new! I just replaced tires, and that had no effect. Car not showing any fault codes. I was thinking perhaps the ESP electronic stability is overactive playing with rear brakes causing the premature wear and odd handling (or bad wheel speed sensor) but wouldnt either of those throw a fault code, or I'd see the ESP dashlight come on? Suspension components all look fine, not seeing any play or deterioration. Thoughts? Anyone else seen this? Thanks SO much!

 

When the last time you had wheel alignment?
Sounds like you have sticking callipers

 

@Leetom Assist systems use rear brakes. Examples - Distronic, standard/base cruise control, lane keeping assist, HOLD, ESP, 4ETS and probably others. Use of assist systems accelerates rear brake pad wear.

Regarding wandering, can you post good clear photos of each of your tires, giving a clear view of the tread on each tire? How long have you owned the vehicle, and how many miles have you put on it?

 

No active assist on car (except for collision avoidance), owned since new...November 2012, brand new tires (did with old and now new tires), I just replaced rear brakes and thoroughly cleaned, inspected and lubed (pins) rear calipers. Nothing appeared abnornal or sticking on them. Old tires had even wear (for an ML550....that are slighly biased.to inside).

 

Correction/clarification...car is on 3rd set of rear brakes at 58k miles (replaced 2x), and is a 4matic, offroad pkg, electronic drive modes with adjustable electronic shocks, and airmatic suspension (if any of that matters). Car is not hot-rodded, and ALL maint is done and on-time by either myself or MB dealer.

 

@Leetom Thanks for the history. Your vehicle uses rear brakes for, at a minimum, basic cruise control. You have additional options on your vehicle that likely use the rear brakes.

Three sets of brakes in 58k miles is excessive in my view. Do you have an aggressive driving and braking style? Or does the primary driver of the vehicle drive with a foot on or near the brake pedal often?

 

Almost never use cruise control, and I drive real gentle...as evidenced by the still new looking original front brake pads (never changed since new). Dealer even commented the fronts look nearly new. Im thinking maybe the yaw sensor for ESP is bad, causing ESP to be overactive hitting rear brakes, causing the wandering effect I described earlier? But wouldnt that at least flash the ESP dash light? Dealer said MLs go thru rear brakes like crazy, but this seems excessive to me...especially since Im experiencing the highway wondering.

 

BTW, dealer will only diagnose using trouble fault codes stored in computer. Since it isnt throwing any, they are happy to just start replacing parts for big $.

 

Our 2013 was bought with around 12k miles in 2018, running on original brakes. We replaced the fronts last yr at around 30k miles, and mostly for a front brake chatter.
We're at 70k km/+/- 45k miles....still on the OEM rear brakes & the wife drives (and brakes) the poor thing like a bat outta hell. Your dealer is full of it...

EDIT: Hardly ever use cruise control, lane departure as well, even though lane departure surely has little to nothing to do with this discussion.

 

I disagree with your assessment of the dealer, if anything I agree with the dealer. I drive opposite to your wife, in fact I drive like the OP gentle as can be, I am still on the factory front pads now with 90,000 miles, and gone through probably at least 2 sets of rear pads. I have had discussions like this on another car forum, and it's the same. There are some owners on that forum, that swear up and down front brakes are suppose to wear out faster and they claim like you there is something wrong with our vehicles. And yet there are plenty of owners on that forum where there rear brake pads wear out at nearly twice the rate of front pads.

I strongly believe the disparity in front/rear pad wear rates is entire dependent on how the vehicle is driven. I log 10,000 miles in usually 6 months and I can tell you there are plenty of drivers out there that will toast front pads easily. In fact prior to the recent changeover to ceramic brake pads, you could tell plenty of vehicles out there had very very black/dirty front wheels and only the front wheels because those drivers braked at the last possible moment and as hard as possible. And you could see this as you followed these drivers. They had very very dark/black front wheels. But with the new ceramic brake pads, it's harder to see now. But you can still see based on other's driving habits. Brake as late as possible and brake as hard as possible. Me? No, I brake as early and as light as possible.

 

Etienne, if you were to agree with me, I'd pinch myself to see if I was in a wet dream.

It's common knowledge that the front brakes do most of the work, which is why they're replaced more often. I own a fleet of five service vans plus a pick-up, not to mention the vehicle I drive myself. We always do at least one front brake job before doing the rears, and usually it's 2-3. I have techs with different driving methods. Some are cowboys, some are as comatose as you claim to be. The brakes always wear out quicker up front.

Always Etienne. Always...

 

Yeah, thats what I figure too, as why fronts on this ML are about 2X as large as rear, which is why I think the quick wear on the rears is unusual, and related to my wondering problem. Dealer told me that ML rears wear out 2x faster than fronts (Im experiencing way more than that based on current pattern) because Mercedes calibrates the car to hit rears slightly before fronts to give a smoother braking experience. (Had 2 separate dealers tell me this, in 2 differnt states) Not sure I buy that. I may take it in and have them drive with a reader to see if rears are indeed activating unexpectedly while just normal driving (earlier thread suggestion). I hate paying their crazy high prices when Ive found most work I can do myself for WAY cheaper.
Example....one rear adjustible shock went bad and I got 2 dealers to both quote $1800 parts and labor. Decided to do it myself (never did one on this car before...little more involved getting to top of shock from inside, but beyond that, no biggie...3 bolts) took me 2 hours and the OE MB part from an out of state dealer was $500. 2 hours of my time, saved me $1300! I actually went back to dealer, asked why price so high. Response was that it was $800 retail for the part, and was an 8 hour job at $125/hour. Told them I didnt know the shortcuts their techs should know and I had job completed in 2 hours!
Because Ive found dealers tend to just swap parts (at high cost) rather than truly diagnose issue (I have several examples of that too), was hoping to get some thoughts from the community so I could focus the diagnosis for them. Or even better, was hoping to get a "yes, I had same problem, it was blah blah blah".

 

LOL Don't get me wrong. I don't disagree with you that "most" braking is done by the front brake pads. I ride a BMW R1200RT motorcycle, and I would say nearly 90% of the braking power comes from the front pads, hence there usually are 2 rotors on the front, 2 calipers on the front and therefore 4 brake pads on the front. The weight shift on motorcycles results in rear lock-up easily. However motorcycles also wear out rear pads faster as well. Why? Because we use the rear brakes more often and longer. We initiate braking with rear pads first to trigger the weight shift, this is usually done with a 1 sec delay before apply the front brakes. The last 10 ft of braking is done only with the rear pads to prevent front end brake dive which potentially causes a tip-over! Slow speed maneuvers are typically done dragging the rear brakes as well. However if I am doing 130 kph and need to drop down to say 30 kph, you bet I'll be apply the front brakes like crazy along with the rear brakes.

How will the brake pads wear on the Subaru now that my son is the primary driver? I have no idea. I suspect more like what you suggest (front wear faster) as he tends to be very very late with his braking and dives on them at the last moment. We shall see!

 

Just a thought on your wandering... I have no experience in strut change-out and alignment on a ML, but might you need to align after change in strut? At best, putting new shoes(tires) on without doing an alignment is always questionable...

 

Change out was a rear electronic shock (not a strut)...changouts on these are pretty simple, and don't require alignment like a strut would. The Wandering problem predates the shock changeout and tires, so the alignment won't solve the issue...however I AM going to get new alignment with the new tires installed. Plan to have dealer take a hard look at the rear pad wear/wandering issue at that time by driving it with a reader in the car to see what the heck is going on. Not holding my breath they will figure it out tho.

 

I would still take a closer look at the alignment. I used to own a car with severe toe in on both rear wheels and that caused exactly what you describe when hitting a slippery patch. The rear tires wore out very fast as well mostly on the inside.

Do you see the traction control or other lights blink or hear anything actuate when you get this wandering?

 

Shouldn't severe toe-in cause outside tire wear and not inside tire wear. That sounds more like severe toe-out for outside tire wear.

 

No uneven wear noted on the tires I just replaced. No traction control or ABS lights blink when it wonders. Ive even tried to switch off the traction control (dash button), but no effect on the issue. Ill definitely run this to dealer to align since I have new tires, to rule alignment out. Will have them check traction control system at that time. I still find it very odd Ive burned through 2 sets of rears while fronts are nearly new looking still at 60k miles (nearly full thickness on pads left).

 

Tire pressure over 38 psi, and worn front control arms will cause the W166 to walk around like an Irish'person on St. Patrick's day at freeway speeds on a perfectly flat, smooth stretch of road.

No offense to Irish'persons intended!

I picked up an 80k 2013 W166 ML350 just recently and had an identical experience. It's obvious that it was sitting in the hot sun outside in southern california because every piece of rubber under the chassis is some form of melted / degraded beyond spec.

I replaced the upper and lower control arms under warranty, as well as the engine mounts, transmission mount, and flex disk.

The control arms fixed the wandering, according to the mechanic the secret is the big ball that carries nearly all the weight of the vehicle in the front. When that rubber ball socket deforms the geometry of the front suspensions starts wandering quite a bit. There is a repair kit for it, but it's not recommended as it's not possible to do it without compromising the long term safety of the control arm. The lower control arms are pricey... ~700 each OEM, and the Lemforders are still half that. But of the things that I had done, it was the biggest safety improvement to the vehicle made after I purchased it a few months ago.

I had the alignment checked before and after, and it was close before but couldn't be corrected to spec until the arms were replaced.

According to the Indy mechanic I had do it under 3rd party warranty (included for free with the vehicle otherwise I wouldn't have touched it, they wanted 5k for 25k miles, so the 90 day 5k warranty for free was a gold mine... got at least that out of it) it's pretty common on Mercedes with a ball on the lower control arm to do this with age; and is not a new phenomenon.

I had the dealership do the engine and transmission mounts, and flex disk as I had a leather seat cover that needed replacement under warranty they didn't have time to do before they sold it. I knew the engine mounts were shot the first time I drove it, and the second time I put it in reverse at a grade I knew the flex disk and transmission mount were shot.

I still have to do the rear bushings and likely replace the 4matic transfer box chain or just pickup a new old stock one and install it (it's got a tiny bit of slack in it from stretch, not slipping teeth yet but it's not 100 percent tight).

Photo of the lower control arm bushing at fault here...

 

One additional note, I took photos of all the parts after replacement, and the only 2 parts that showed visible and obvious signs of degradation were the flexdisk (there were microfractures on the surface near the bolt holes), and the engine mounts, because they had leaked.

You can't tell the bushings are bad even with it up on a rack trying to wiggle the wheel, there's not enough weight to do any meaningful deformation with your hand. If they're so bad you can tell with your hand; it's a life threatening hazard at that point.

Also, even with the lower control arms out, without cutting the arms or destroying the bushing trying to yank them out you won't be able to really tell either. It's just dry rubber that the elastomers have degraded and it no longer has enough 'spring' left in it.

Check the ***** for the electric power steering knuckle, but they're likely fine. The OEM ball is quite pricey as it's a critical safety component, but Lemforder makes those as well.

If it's 7-10 years old, has been in heat for that long on and off; the rubber is bad.
Time, temperature, and vibration energy causes it. Mostly time and temperature.

 

Well done, that's quite a list of replacements. Where did you find the vehicle listed for sale?

Did you mention that Lemforder front lower control arms are less expensive than the factory M-B arms? Is the photo the old front lower control arm from the factory? I wasn't following you there. Thanks.

 

I hate to just start replacing parts if it doesn't fix the problem. The car lives inside a garage, so not out in the elements degrading the rubber (except for time). Any way to tell if those bushings are bad...maybe like take a small screwdriver and poke in there to see if the rubber is hard or not? The wondering feels like it is coming from the rear...but not 100% certain. Of course the rear arms are much more expensive :-(. Still wouldn't explain my rapid rear brake pad wearing, but that MIGHT be normal and/or unrelated to my wondering. My gut just told me it was a stability control issue causing the wondering, of which the rear brakes were a symptom, but I don't know for sure. Thanks SatireWolf for giving me something else to look at/consider.

 

The photo is of a factory front lower, it might actually be a w164 and not a w166 but the bushing geometry is identical essentially.

On the rears you can just push out the bushings and replace them as they are cylindrical instead of ball joints.

Honestly the rear the sway bar links are probably suspect. I know mine are squeaky if I go over big speed bumps when it’s over 90F. They are cheap and reasonably easy to replace but likely wouldn’t explain the wandering unless the rear end is so bouncy that it’s literally floating off the road. Wandering in the lane though is nearly always front end drift. Small geometry changes can make big directional changes if the camber and toe are drifting all over the place in the front.

Essentially you have a floating box on your front wheels and there is rubber on every mount point of that box. Once the rubber gets weak the box wobbles all over the place. My lower bushings were definitely hard but honestly other than surface smoothness a screw driver won’t tell you much other than damaging the rubber further. If you live somewhere where the roads are rough, that rubber is toast after 3/4 of a decade and many many miles.

If you’ve ever seen those square rubber blocks under electronics from the 80’s that turn to goo over time, we’re essentially seeing the same effect just the elastomers aren’t holding the rubber together, rather they’re keeping it tight and able to maintain geometry vs sag and float all over the place as it takes suspension forces.

I think the biggest thing to keep in mind here is the ML is BIG and HEAVY compared to the cars that Mercedes builds. So while they may get 100k out of the same component and a decade plus, that same suspension component takes dramatically more punishment on our big heavy SUV’s. It’s why Toyota Tundra 4x4 et al’s have a fraction of the rubber in the drive line. It just dies a brutal death by a thousand bumps and temperature swings and age.

The Lemforder lowers are fine. I just used OEM since warranty was paying instead of me.

These were the factory front arms that came out of my ML350. As you can see the rubber is hard to diagnose by look. I can attest though that it went from scary to near factory feel with four parts. I did order all fresh bolts for safety though and had them all torqued to factory spec.

 

Great posts, Satirewolf. Thanks!!!

 

I picked up my ML350 on Carvana just as the lockdowns were about to abate. They have a ton of clean, full maintenance history vehicles.

I got it for a song, and considering a $5k warranty would have been a third of what I paid I avoided it. Their warranty is through SilverRock who is not the worst to deal with but you will spend a ton of time on the phone hand holding the process to keep the shop from going Apoplectic. They want photos on all parts replaced before and after.

Carvana gives you a short warranty to cover any oversights on the vehicle they missed or are plain safety issues (I had the arms replaced as a safety issue since the vehicle would not track straight in a lane at 60 mph+). It was bad enough that 70 mph was a bit scary requiring constant steering input with any bumps.

The driver seat bottom had a serious rip in the left bolster that the previous owner used an ugly black vinyl sealant to cover up. They actually put in a claim to replace the seat cover for me when they saw it before driving it over to me. This meant Carvana straight up paid for it instead of Warranty but I still had to go through SilverRock.

They had me go to a body shop to get it photo’d and quoted. This worked fine until the shop supervisor got COVID and the shop owner fired everyone. He rehired some ‘good ole boys’ who knew nothing and were useless. The owner flat out refused to do the agreed repair since he ‘wouldn’t make anything on it’. They send out to another shop for interior work.

Lesson learned Maaco is useless and unethical.

Just take it to the dealership and pay the $50 copay for out of network. Just be sure to give explicit instructions from SilverRock on photos and how to submit the repair. And be prepared for your Mercedes techwriter to be super suspicious and overly concerned about not getting paid out and having you on the hook for diagnosis.

i.e. call SilverRock first and work out all the details you can before hand. They are all nice people if you are courteous to them and want to help you. The process is just slow. You can speed things by calling them 30 min after the shop submits photos and having a CS rep ‘upload the photos’ for the adjusters to look at. At which point once confirmed the shop can call back and get an adjuster to inspect while they’re on the phone. Instead of waiting 24-48 hours. SilverRock was overloaded with car sales as the lockdowns began to end and had everything backed up for days and weeks if you didn’t stay on top of it. Also not their fault, they all had to go remote work outside their offices without prep like most other companies. It’s way better now.

I had roughly 5k in warranty repairs mostly because I was patient and kind, and worked nearly 90 days almost past when the warranty expires trying to get it repaired at the first shop (Maaco).

The repair experience wasn’t their fault, just use a quality trusted shop and you’ll be fine. I had zero issues with a Mercedes certified Indy mechanic getting the upper and lower control arms warranty repaired.

I took it to a local dealer for the seat cover finally. The Mercedes dealership noticed the engine and transmission mounts were oddly covered by the warranty so they submitted for those as well. I paid them for the flex disk since it’s easily done while doing the transmission mount.

All in all, any 75k+ 5+ year old luxury vehicle is going to have wear and minor mechanical issues either immediately or borderline needing work with suspension / quality of life issues (mounts, belt pulleys, hoses) that will need work. But that’s part of the cost of ownership on a 10-15k vehicle you can possibly just pay cash for.

The battery is still factory flooded lead acid after all this time, so I picked up an interstate H8 AGM for $150 (Autozone and Pepboys H8’s are all built by Johnson Controls, as is the Mercedes OEM in NA).

I also picked up an OEM aux battery to replace proactively along with a Bluetooth battery charging logger and an on board Noco 2a charger I installed alongside the main battery.

With everyone working from home, leaving the battery a week plus at a time along with short trips without a full charge isn’t very kind to it long term.

I wish I could put a German built Varta Silver dynamic AGM in, but alas I’m not willing to import a battery I can’t even warranty! The OEM appears to be a Varta and that’s lasted forever.

Would I buy another from Carvana? Absolutely. You get a week to return or swap with zero hassle or risk so you can fully inspect and put it through the paces.

Not having to deal with dealer lots, and sales droids was refreshing and having a used vehicle delivered to my garage like a brand new vehicle was great. They used gloves, masks and sterilized everything prior to delivery.

Yes there’s paint blemishes and swirl marks, and other things older cars that haven’t been babied by an OCD owner have but for the price, function, and quality mechanically after fixed up? It’s a steal.