How To Make My 2015 ML350 Last 300k Miles?
So far whats been done on the car:
Front/rear Brake Pads at 37k
Computer Reprogrammed at 37k
Fuel System Leak repaired at 40k
Steering Gear repaired at 47k
Spark Plugs replaced at 47k
Transmission fluid/seal at 53k
Front/rear Brake Pads at 61k
Brake fluid flush at 92k
I found a local Mercedes only shop and wanted to get a lot of preventative maintenance done. What else should I get done to make the original trans and motor last 300k miles. Thank You Guys!




So far whats been done on the car:
Front/rear Brake Pads at 37k
Computer Reprogrammed at 37k
Fuel System Leak repaired at 40k
Steering Gear repaired at 47k
Spark Plugs replaced at 47k
Transmission fluid/seal at 53k
Front/rear Brake Pads at 61k
Brake fluid flush at 92k
I found a local Mercedes only shop and wanted to get a lot of preventative maintenance done. What else should I get done to make the original trans and motor last 300k miles. Thank You Guys!
1 - Due for 60K miles spark plug since last change
2 - Transmission service every 60K/years miles since last service
3 - Brake fluid flush (20K miles since last service or every 2 years)
4 - Check your brake rotors/pads. Yours are wearing too soon, in my experience. On the E350, my brake lasted 106K miles and they were not to the sensor yet, so I could have easily driven @5K more. On the 2012 ML350, just did the front rotors/pads at 141K miles, and the last brake service was @60K miles if I recall correctly. So about the same mileage, though the pads were thinner than the E350 ones.
5 - I would check engine/transmission mounts at this mileage. The 2015 ML is fine @96K miles, but the 2012 is asking for engine mounts (driver's side is shot).
6 - I would check front suspension components: control arms, bushing wear out, and if the vehicle becomes noisy. Also, check the sway bar links (they would start making noise like maracas at some point)
7 - Engine air filter, clean (blow in reverse) it every oil service and replace every 20K miles.
UPDATE: Forgot to mention -> 8 - Differential service at @100K miles: rear, front/transfer case (4matic).
Last edited by JCM_MB; Oct 29, 2025 at 01:38 PM. Reason: Additional info
Also for one sometimes the parking sensor button on the dash turns red (turns off) and doesn't want to turn back on until i restart the car. Then secondly my lift gate would sometimes would not lift up until I try it a second time and then it works as it should.\
What do you think about my symptoms? Have you encountered anything like I have?
1 - Due for 60K miles spark plug since last change
2 - Transmission service every 60K/years miles since last service
3 - Brake fluid flush (20K miles since last service or every 2 years)
4 - Check your brake rotors/pads. Yours are wearing too soon, in my experience. On the E350, my brake lasted 106K miles and they were not to the sensor yet, so I could have easily driven @5K more. On the 2012 ML350, just did the front rotors/pads at 141K miles, and the last brake service was @60K miles if I recall correctly. So about the same mileage, though the pads were thinner than the E350 ones.
5 - I would check engine/transmission mounts at this mileage. The 2015 ML is fine @96K miles, but the 2012 is asking for engine mounts (driver's side is shot).
6 - I would check front suspension components: control arms, bushing wear out, and if the vehicle becomes noisy. Also, check the sway bar links (they would start making noise like maracas at some point)
7 - Engine air filter, clean (blow in reverse) it every oil service and replace every 20K miles.
UPDATE: Forgot to mention -> 8 - Differential service at @100K miles: rear, front/transfer case (4matic).
I meant to add you as a quote for my other message, just joined today learning everything, lol




Also for one sometimes the parking sensor button on the dash turns red (turns off) and doesn't want to turn back on until i restart the car. Then secondly my lift gate would sometimes would not lift up until I try it a second time and then it works as it should.\
What do you think about my symptoms? Have you encountered anything like I have?
Intermittent behavior that comes and goes with car restarts are, in my humble opinion, due to poor communication between modules because of low voltage, grounds or a confused/hung module clogging the network. Basically, it needs a Ctrl-Alt-Del to reboot the whole car. The E350's transmission was ocassionally hanging "no shift forward/reverse" after a long drive, or "under the weather". Read it could be the SCM, TCM, shifter, etc likely $$$$ cost. Charged my batteries and cleaned a few grounds on the driver's side. It has not done it in @2 years. Cost = $0, though I got a used SCM just in case. I need to remove the EIS and do some preventative maintenance though. Check @CaliBenzDriver posts about all the electricals in this MB generation: W166/W212/W204 (all the same)
-front and rear differential fluid change,
-transfer case fluid change,
-coolant flush/fill,
-cabin air filters (3),
-airmatic filter(s) change,
-cam position sensors and magnet pickup -inspection for oil (change if any oil present in wireclip),
-serpentine belt
-check your driveshaft CV joint boots for crack/wear (fairly easy to just replace boot and not entire axle on these...joint comes apart fairly easy).
Last edited by Leetom; Oct 30, 2025 at 08:59 AM.




-coolant flush/fill,
-cam position sensors and magnet pickup -inspection for oil (change if any oil present in wireclip),
-serpentine belt
-check your driveshaft CV joint boots for crack/wear (fairly easy to just replace boot and not entire axle on these...joint comes apart fairly easy).
Have you done the coolant drain/fill already? How many miles? If you did, did you replace the reservoir as well? If you also replace the reservoir, did you cut it to see inside? MB specifies 150K miles/15 years.
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Intermittent behavior that comes and goes with car restarts are, in my humble opinion, due to poor communication between modules because of low voltage, grounds or a confused/hung module clogging the network. Basically, it needs a Ctrl-Alt-Del to reboot the whole car. The E350's transmission was ocassionally hanging "no shift forward/reverse" after a long drive, or "under the weather". Read it could be the SCM, TCM, shifter, etc likely $$$$ cost. Charged my batteries and cleaned a few grounds on the driver's side. It has not done it in @2 years. Cost = $0, though I got a used SCM just in case. I need to remove the EIS and do some preventative maintenance though. Check @CaliBenzDriver posts about all the electricals in this MB generation: W166/W212/W204 (all the same)
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Insect the cam position sensors and cam magnets fornsigns of oil in the connectors. It is almost for sure there with a car this old. Replace the sensors and magnets. Check the ECU connector for signs of oil and clean it if needed.
Last edited by chassis; Nov 2, 2025 at 09:57 PM.




Now, a mechanic that tells me the oil leaking through the timing covers edges, or through the actuator seal can make it to the ECU will automatically loose complete credibility with me. The oil in harness issue has nothing to do with this kind of leaks, but oil through the physical plastic of the actuators, the plastic of the camshaft position sensors, oil pump solenoid, and possible other similar component. You can have oil in harness issue w/o a single visible drop oil outside until it is so much oil in the connector the connector will leak it out.
Since the timing covers will be already out, I would definitely replace the chain tensioners just because it shouldn't be much more cost wise.
Since the VVT are also visible, worth doing a manual test to check if any VVT is already failing.
Check every connector for oil in harness. For a 2015, it can be hit and miss. We have 3 of these engines (2012, 2014, 2015), none have leaked oil from anywhere, timing covers, seals or through the connectors. It can be weather related due to the seasonal cycling. Ours are Florida based, i.e. narrow temperature range that North based vehicles.
My 2c
Last edited by JCM_MB; Nov 2, 2025 at 10:14 PM.
Insect the cam position sensors and cam magnets fornsigns of oil in the connectors. It is almost for sure there with a car this old. Replace the sensors and magnets. Check the ECU connector for signs of oil and clean it if needed.
110 ENGINE DIAGNOSIS (GASOLINE)
108911 CEX 91.80 91.80
4 276-905-10-00 POSITION SENSOR




110 ENGINE DIAGNOSIS (GASOLINE)
108911 CEX 91.80 91.80
4 276-905-10-00 POSITION SENSOR
The current practice, started by MB in their previous generation engines with VVT, is to use sacrificial harnesses such as
OF COURSE --> PLEASE DISCONNECT THE BATTERIES when working with electricals and spraying connectors.
Last edited by JCM_MB; Nov 3, 2025 at 10:50 AM.
The current practice, started by MB in their previous generation engines with VVT, is to use sacrificial harnesses such as Amazon, M276/278 harnesses
OF COURSE --> PLEASE DISCONNECT THE BATTERIES when working with electricals and spraying connectors.




Changing the non-failed camshaft position sensors or solenoid actuators will not prevent anything either. A new part is not guaranteed to work better than a non-failed part. It is a statistical game about quality control.
Changing the non-failed camshaft position sensors or solenoid actuators will not prevent anything either. A new part is not guaranteed to work better than a non-failed part. It is a statistical game about quality control.
If any of you can give input that would be amazing since ill be revisiting my mechanic tomorrow on what to do next for the leaking upper timing covers!
One other thing to note is once before (like 3 or 4 weeks ago) i tried to start the car and the car did not crank then when i took out the key and reinserted it, it started fine. although I had my old battery on at that time (original 10 year battery) when that happened but since then I changed the battery out a few days ago and not had it repeat or anything.
Last edited by YASML350NJ; Nov 5, 2025 at 03:33 PM.
https://www.youtube.com/watch?v=XVpEEN7zbYw
that videos startup sounds much different than mine, his sounds like something is knocking in there. Mine in just unusually loud for 30 seconds or so in a cold start and goes away. What do you guys think?




Last edited by JCM_MB; Nov 6, 2025 at 08:52 AM.




https://www.facebook.com/share/v/1D3x6E4san/
From what I have seen so far, the photos and the videos, and if this were my ML, I would carefully clean the timing covers with a "brake cleaner" wetted drag/brush, no spray anything, and recheck the area a few days later and see how it progresses. If you decide the oil leak is critical to fix immediately, I would replace the chain tensioners simply because it is an open and straightforward task.
My 2c
Last edited by JCM_MB; Nov 6, 2025 at 11:19 AM.
https://youtube.com/shorts/dQbjfNBp4...jFsjj4nHLnWlG3
If any of you can give input that would be amazing since ill be revisiting my mechanic tomorrow on what to do next for the leaking upper timing covers!
One other thing to note is once before (like 3 or 4 weeks ago) i tried to start the car and the car did not crank then when i took out the key and reinserted it, it started fine. although I had my old battery on at that time (original 10 year battery) when that happened but since then I changed the battery out a few days ago and not had it repeat or anything.






