High mileage W166s (80k+)?




radiator replaced as it had a leak.
did have to replace the adblue line from the tank and rear springs and breaks but I do all that myself.
overall very happy, has odd intermittent “won’t shift from park to D or R” issue that I believe is more of a software timing issue than hardware but could be a module. Only does this when below 0 or so. Startup only, never after its warmed up. No noticeable rattle from timing chain yet (crossing fingers here)
check from MB made me smile, paid 15K for this rig at 100K so I feel good about this thing and would even put a new motor in it if it failed.
should get more than 45K on a set of tires though in my opinion, especially with mostly highway driving.
I have always felt that diesels work best when run consistently for longer times. 3 miles to Starbucks and back isn’t good for any vehicle let alone a diesel.
I would buy another one like this for the right price any time. Can’t find any deals like I got right now though




- Removed a little bit of surface corrosion from the trailer hitch using detailer's sanding blocks and a wire wheel on my drill, performed a proper metal surface prep, and then applied several coatings of POR-15, followed by a top-coat anti-corrosion paint (trailer hitch corrosion is also common up here in the northeast);
- Preventative maintenance: Replaced all camshaft position sensors with the latest revision and also installed the adapter wiring harnesses for camshaft adjuster solenoids (i.e., Mercedes part#: A2711500156...what some refer to as the camshaft adjuster solenoid "pigtails" or "sacrificial harnesses") between each of the solenoids and the engine wiring harness connectors. Although these components were specified for the earlier M272 and M273 engines as part of Service Campaign No. 2012070002, they are also compatible with the camshaft adjuster solenoids for the M276 engines. This was done to avoid having oil leak from the connectors of these components into the engine wiring harness;
- Paint correction and Ceramic Pro coating;
- NH Oil Undercoating service in the fall;
- 80,000 mile service performed at my Mercedes-Benz dealer at the end of the year
***
Until last month, I would have said that the car has been absolutely trouble-free, but I experienced my one, and only, breakdown...and it was a strange one. I had just completed the first 100 mile leg of my trip on Saturday of Labor Day weekend and, following the brief 45 minute stop at our destination, was about 20 miles into the return leg back home when I suddenly stalled on the interstate turnpike/tollway. The check engine light then came on as I coasted into the breakdown lane. I had my Autel scanner with me, since I was on a car hunting trip for my mother. I plugged it in, turned the key in the ignition to the first/"on" position (i.e., but without attempting to start the car), and then pulled the following codes and saved the freeze data:
- ECM (Engine Control Unit) P008A00 The pressure in the fuel low pressure circuit is too low. Active
- ECM (Engine Control Unit) P008700 The fuel pressure in the system is too low. Active and stored
- ECM (Engine Control Unit) P241500 The signal of oxygen sensor 1 (cylinder bank 2) is implausible. Active
- ECM (Engine Control Unit) P241400 The signal of oxygen sensor 1 (cylinder bank 1) is implausible. Active
- FSCU (Fuel Pump Control Unit) P008700 The fuel pressure in the system is too low. Active and stored
- FSCU (Fuel Pump Control Unit) P008A00 The pressure in the fuel low pressure circuit is too low. Active and stored
Sat for about 6 months in 2020 without being started, which is my bad I should have gone and started it every 2 weeks or so but was more or less out of my control, started up with some misfires and threw check engine light. Smoothed out after a minute or so but took it to the shop anyway and they replaced an injector. In hindsight I don't think it needed replaced at all but the shop did.
Beyond that, all preventative maintenance. Recently had the transmission/diff/transfer case fluid + trans filter swapped and some new rear rotors.
Hoping she makes it to 300k!
Replaced fluids on diffs/tcase/brakes/trans.
Spark plugs at 60k and a couple ignition coils since I broke them.
Front brakes
The Best of Mercedes & AMG




- If you are near or over 100,000 miles and haven't done so already, I would consider replacing the ignition coils at the same time as you replace your spark plugs. At least on the 2015 ML 350s (not sure what other model years are applicable), it's pretty common for them to fail at around 7 years/100,000 miles. You can search through the forums to confirm this anecdotally... In my case, I didn't quite reach 90,000 miles before having a problem with one of my coils. When I started my car one morning during the Fourth of July weekend last year, the SUV ran REALLY rough, and the Check Engine light came on shortly thereafter, so I shut the vehicle off and scanned for codes. This is what I found:
1. ECM (Engine Control Unit) —— ( 8 )
1.1. P13B200 Electrical fuse 1 for the ignition coils has a malfunction. Stored
1.2. P035196 The actuation of ignition coil 1 has an electrical fault or open circuit. There is an internal component fault. Stored
1.3. P035296 The actuation of ignition coil 2 has an electrical fault or open circuit. There is an internal component fault. Stored
1.4. P035396 The actuation of ignition coil 3 has an electrical fault or open circuit. There is an internal component fault. Stored
1.5. P209000 Actuator 'Exhaust camshaft' (cylinder bank 1) has a short circuit to ground. Stored
1.6. P208800 Actuator 'Intake camshaft' (cylinder bank 1) has a short circuit to ground. Stored
1.7. P034300 The position sensor of the intake camshaft (cylinder bank 1) has a short circuit to positive. Stored
1.8. P036800 The position sensor of the exhaust camshaft (cylinder bank 1) has a short circuit to positive. Stored
To get to the bottom of what exactly had caused the fuse to blow for that bank, I needed to have some actual diagnostics performed. Unfortunately, between holiday family commitments, an ongoing building remodeling project in which I was our own general contractor, and the non-stop, record-breaking rainy weather up here, there was no way I could get to this job myself. I called our local independent Mercedes specialist shop in the area, described the issue and the codes I had read with my scanner, and suggested that it might be a frayed section of the wiring harness to that bank (this car sits outside for extended periods, and squirrel damage is always a possibility...) or a bad coil that had shorted. They already knew that I had checked to make sure that there had never been any oil in the engine wiring harness and that I had performed the necessary preventative maintenance to avoid this problem back when I got the car (i.e., I had all of the camshaft position sensors replaced with the latest revision, checked the camshaft adjuster magnet solenoids, and installed the adapter harnesses/"sacrificial pigtails" as a precaution). I had the car taken to the mechanic right after the holiday. It turned out that the ignition coil 3 was shorting, so I had him replace all of the ignition coils with the current Genuine Mercedes coils from the dealership while he was in there (I'd recommend just getting the OEM Bosch, since they seem to be available again...there were supply chain issues over a year ago). The ignition coils were on special order from the local dealership, so we had to wait 2 days for them to arrive. The previous owner had the dealership replace all of the spark plugs at around 52,000 miles. I did have the mechanic check spark plug 3 for fouling, and it looked fine (they had been replaced only ~35,000 miles earlier, and I had not experienced any misfiring during my ownership), so I didn't bother to have them replaced yet. These spark plugs tend to have a long lifespan from what I have heard. As for the ignition coils installed in that particular model year...not so much, it seems. The manufacturer for the OE coils back then was BERU, and many customers reported even more premature failures with BERU aftermarket replacement OEM coils during the pandemic, when the updated Genuine Mercedes and OEM Bosch ignition coils were still on backorder. FCP Euro, for example, doesn't even offer the BERU coils for the M276 engines anymore... - In the late summer of last year, I was inspecting the windshield cowl drains prior to bringing my car to the car wash when I noticed that two of the rubber wiper spindle/linkage grommet seals (i.e., the one on the driver's side/left end and the second one over from the left, near the middle of the windshield) had cracked open due to exposure to the elements over the years. I noticed that the grommet seals were permanently fused into the cowl as one piece with the entire water drain panel/cowl (without Magic Vision feature; Mercedes-Benz part#: 166-830-00-28), which would have to be replaced. Parts sites, including both Mercedes-Benz dealerships' websites and independent parts dealers (and eBay Motors), listed the part as "discontinued," and MBUSA's sites fail to even display a page for the part. Luckily, the parts guy at my dealership in town was able to track one down through their dealership network and request it via special order for around $170 back in August. I asked him whether it was a common part request, and he seemed to think not. ...However, when he took a look at his own ML 350's windshield cowl, he discovered that the same grommet seals had torn... Lesson: Inspect those seals. There are some Chinese knock-offs available online, but I have no idea as to their durability. Used ones pulled from junkyards that I saw online seemed quite weathered and not especially cheap when factoring in shipping. After replacing the water drain panel/cowl with the new one from the dealership, I saved my old one and picked up some of the cheap, older wiper spindle/linkage seals (Mercedes-Benz part#: 170-824-00-98) and some 50mm wire grommets. Using some industrial-strength (i.e., much stronger than JBWeld) 3M PR600 Scotch-Weld, I was able to replace the seals in the old water drain panel/cowl with the new grommets and seals. I'll offer it at some point.
- I had been putting off replacing the chrome-finished plastic rear bumper step pad (Mercedes-Benz part#: 166-885-21-74), which the SUV's previous owner had gouged in several places, as I had been informed that the entire rear bumper cover would have to come off to replace it. By last fall, it had begun to peel in those spots. Based on what I read in the X166 forum, it seemed possible to carefully pry it out on the GL/GLS chassis models and replace it without removing the bumper cover. Comparing the bumper step pads' fastener tabs for both chassis, it seemed like that might also work for the W166 chassis, so I gave it a try... In the course of performing this replacement, I discovered that the slots in middle of the W166 bumper cover are thinner (the two slots at both ends appear to have been designed with a taller cut-out to allow the tab to be slid out after prying it upwards...but not the middle slots on the W166 bumper cover, for some reason...), so simply prying up doesn't work, unlike with removing the tabs from the two sets of slots at either end (those tabs slide out easily when prying them upwards). I ended up having to snap off the plastic tabs in the middle of the old step pad. Luckily, I did not damage the bumper cover whatsoever and was able to replace the step pad without any further issues. Whew... I have photos of the entire process and the end result.




Weird fact/situation. During DPF regens, my suv will sometimes run rougher. I can sometimes feel a vibration while driving, like a wheel that's unbalanced and the dash will send a message to check tire air pressure. Everytime I pulled over, the tires seemed fine and the SUV would have a very strong burnt plastic/metal smell. I know this is related to the DPF doing a regen, but this is happenning maybe once every 10 000 km. It's very weird. The rest of the time, the other regens don't seem noticeable. My Autel scanner shows no codes every single time.
Right now, the oil cooler seals are slightly leaking. They were never replaced and, since the leak is very minor, I'm debating whether to replace them or not. I don't even have to do top offs between the 10 000 km OCI. I do pretty much all of the work and maintenance myself, but this is a big job that goes beyond my comfort level. If anyone is near the Ottawa/Montreal/GTA region and can do the job please send me a private message.
The other thing (which is minor also) is during very cold or very hot days, the panoramic roof will sometimes squeak when hitting a patch of rough road. It's very bizarre and it seems to happen more often when the left wheels hit a bump/crack/manhole on the road. I will have to investigate some more. There seems to be other threads about this (from other models as well, not just the w166) and they point to the screws in the T pillar near the panoramic windows going loose.
I'm not sure what I'll do once my AEM warranty is over. I'm debating on whether to keep it and tough it out (since it's not worth much due to the very high mileage) or to sell it and switch to a 2018/2019 GLE400 with the gas engine. I made a thread about this in the W166 GLE forum.
Link to the maintenance sheet:
https://docs.google.com/document/d/1...t?usp=drivesdk
Last edited by Potrice; Feb 29, 2024 at 08:35 AM.
My 2013 is at 87k miles after this winter is over I plan to take off a lot of plastic trim and do a deep clean of the under carriage and inspect the body.
We decided to sell my GTI and keep the ML350 since my family is getting larger and I will need to drive the ML to the ground, hoping for as many years of service as possible!




My 2013 is at 87k miles after this winter is over I plan to take off a lot of plastic trim and do a deep clean of the under carriage and inspect the body.
We decided to sell my GTI and keep the ML350 since my family is getting larger and I will need to drive the ML to the ground, hoping for as many years of service as possible!




Also... Back in February, when I had its Service B performed, I had my Benz indy shop (603 MTech) check for oil in the engine harness connectors that I had not checked previously, including at the oil level sensor connector and oil pump control valve solenoid connector (I decided to have them re-connect it after inspection), and they were all clean...no oil seepage yet.
Last edited by Œuvre; May 19, 2024 at 01:03 PM.
It's a high maintenance Mercedes, not a honda. I wouldn't swap it for said honda.
I do believe the secret to longevity for a bluetec is to treat it like a diesel, not a grocery getter. Short trips are not a friend of this engine.
Oh, and OIL. Change the oil at shorter-than-recommended intervals. Use a desludge solvent every other change or so. You'll know if it is working because you'll be able to fit the full recommended volume of oil into the engine without making the dipstick tube say "TOO MUCH!"
Last edited by rapidoxidation; Apr 25, 2025 at 10:13 AM.
report back on motor mounts soon
2014 ML 350 Bluetec
report back on motor mounts soon
2014 ML 350 Bluetec




Last edited by Œuvre; May 14, 2025 at 03:06 PM.
I absolutely love love LOVE driving the car. The fuel economy is incredible - I've seen a 6 handle on the litres per 100 km. but typically it gets down into the mid to low 8's. It seems to actually do better at 110+ km than it does at 105. Most of my trips are minimum 200 km. I put new tires on it last fall and got my Indie to align it to my preferences (ie. get rid of the stupid negative camber settings). I've got a 50th high school reunion coming up next weekend and I'm literally looking forward to the 4 hour trip as much or more than I'm looking forward to seeing classmates I haven't seen for 50 years.




Then, I had my annual maintenance service this past winter when the SUV had a little over 95,000 miles on the odometer. Tire Rack had their end of year deal on Pirelli Scorpion Weatheractive tires into early January, so I had picked up a set of them to replace the Bridgestone Dueler H/L Alenza Plus tires installed at the dealership by the previous owner. Each of these old tires had a different date code (early 2018, late 2018, early 2019, and one from late 2020, which had been installed months prior to our purchase of the vehicle). The three oldest tires were already experiencing significant dry rot. As an example, this was the tire with the late 2018 date code:
The tire with the late 2020 date code did not exhibit any serious dry rot yet, and it still had a bit of tread left, so I decided to keep it as a full-size spare together with the rim, as it was also the only rim to have any curb rash:
I was able to find a brand-new replacement rim from the wheel business run out of the Auto Adriatique Garage center in Montreal. Total cost about 265 USD (and they threw in for free a set of 4 brand-new OE TPMS sensors, which matched the old ones installed by Mercedes under the SUV's previous ownership but a newer revision, of course):
The old TPMS sensors:
The new TPMS sensors:
One of the new Pirelli tires mounted and installed:
As for the TPMS code C159916 (i.e., "The battery of the tire pressure sensor has a malfunction. The limit value for electrical voltage has not been attained.") that I have been experiencing since last year, I cleared the stored code, and it didn't come back after the new TPMS sensors had been installed. It was just a battery/batteries getting low in one or more of the old TPMS sensors. There are also no new codes reported after performing a full scan of all of the SUV's modules.
While inspecting the vehicle, the techs noticed the corrosion on the brake pads, and one of the inner ones was delaminating. They showed it to me when the vehicle was up on the lift, and it was really separating. The pads were also getting worn down. According to the service records, the rotors had been resurfaced when the brake pads were replaced under the previous ownership at the dealer, so they were also getting thin. The brakes were due, and I wanted to replace the Genuine Mercedes brake pads (the OE manufacturer was TRW, I believe) with the Akebono Euro pads, which were on sale (the complete set of front and rear pads was on clearance and cost less than $85 in total). For the rear pads, the SUV takes Akebono EUR1630A (corresponds to brake kit Mercedes Benz part#: 007-420-83-20, which has been replaced by 000-420-99-04), and, for the front pads, it takes Akebono EUR1629 (corresponds to brake kit Mercedes Benz part#: 007-420-81-20, which has been replaced by 000-420-13-05). The Akebono rear pad kit comes with wear sensors and anti-rattle springs. The Akebono front pad kit comes with just the wear sensors. When I was looking up parts, I checked the Mercedes parts catalog, but it seems that the rear anti-rattle springs are not available separately from the Genuine Mercedes kit (I couldn't even find separate part #s from Mercedes). None of the U.S.-based parts suppliers had any either, but I think one might be able to find compatible aftermarket ones from vendors in Europe (or on eBay). Had to clean and reuse the old ones, since the ones that come with the Akebono rear pad kit don't fit correctly.
The spring clips for the front brake pads are available separately from Mercedes (possibly the same as those used on other makes and models), so I picked up a set from a dealership to replace the rusty ones on my vehicle (we're in coastal northern New England...).
The coating on the Genuine Mercedes rotors that came with the vehicle had held up well in our salty environment, and we were OK with their braking performance, so I decided to just get the coated rotors from Brembo, the OE manufacturer for the Genuine Mercedes rotors (both manufactured in the U.S.).
The Genuine Mercedes front rotors.
I purchased the Brembo coated front rotors, which are the OE equivalent.
The Genuine Mercedes rear rotors.
I purchased the Brembo coated rear rotors, which are the OE equivalent.
The parts prices with the sales discounts applied were pretty reasonable, I'd say:
The only other issue found was that two of the exhaust clamps were getting badly corroded, so I picked up a set from a dealership (they were $15 ea.).
There wasn't any significant corrosion or cracking of the exhaust pipes occurring at the clamps yet, so the local exhaust shop just cut the old ones out and installed the new hardware for 50 USD.
Other than having to address these common maintenance items, I haven't experienced any issues with the vehicle over the previous year.
Last edited by Œuvre; May 24, 2025 at 03:17 AM.




