RMS Fail Club
Super Member
Joined: Jun 2014
Posts: 517
Likes: 71
From: Los Angeles, CA
2019 S63 AMG (Current), 2015 E63S, 2008 E63, 2005 E55
It is an emissions control gizmo, probably required due to the crazy California regulations. Just back-off a little on the emissions regulations, and the vehicles would be much less complex and much more reliable. I'm considering an older car with no emission controls, and no computers, unless it has fuel injection.
Junior Member
Joined: Apr 2025
Posts: 35
Likes: 3
AMG GT 63s
Rear Main Seal Failure Report – Mercedes-AMG GT 63 S
- Year: 2019
- Model: Mercedes-AMG GT 63 S 4-Door Coupe
- Engine Code: M177 (LS2)
- Mileage at Time of Failure: 72,000 miles
- Style/Frequency of Driving: Unknown – I am the second owner
- Original Owner: No – I am the second owner
- Did the Failure Occur Before or After Warranty Expired? After warranty expired
- Has it Re-leaked After Repair? Not yet repaired
- Cost to Repair: Not yet repaired – planning to fix it at an official Mercedes dealership
- Who Repaired It: Planning to repair at an authorized dealership
- Additional Notes:
- I do not know how the previous owner drove the vehicle
- The car was parked and not driven for 7 months
- I do not know how the previous owner drove the vehicle
Super Member
Joined: Jun 2014
Posts: 517
Likes: 71
From: Los Angeles, CA
2019 S63 AMG (Current), 2015 E63S, 2008 E63, 2005 E55
Rear Main Seal Failure Report – Mercedes-AMG GT 63 S
- Year: 2019
- Model: Mercedes-AMG GT 63 S 4-Door Coupe
- Engine Code: M177 (LS2)
- Mileage at Time of Failure: 72,000 miles
- Style/Frequency of Driving: Unknown – I am the second owner
- Original Owner: No – I am the second owner
- Did the Failure Occur Before or After Warranty Expired? After warranty expired
- Has it Re-leaked After Repair? Not yet repaired
- Cost to Repair: Not yet repaired – planning to fix it at an official Mercedes dealership
- Who Repaired It: Planning to repair at an authorized dealership
- Additional Notes:
- I do not know how the previous owner drove the vehicle
- The car was parked and not driven for 7 months
- I do not know how the previous owner drove the vehicle
Junior Member
Joined: Apr 2025
Posts: 35
Likes: 3
AMG GT 63s
Yes, I do see oil leaking — but only after removing the underbody shield. The engine oil collects on the cover beneath the transmission, so it’s not immediately visible on the floor. I cleaned the area several times and drove the car, but the oil kept coming back. I'm in Ukraine and still trying to resolve the issue. The dealer confirmed it's likely the RMS, but they’ll only be sure after removing the transmission.
Super Member
Joined: Jun 2014
Posts: 517
Likes: 71
From: Los Angeles, CA
2019 S63 AMG (Current), 2015 E63S, 2008 E63, 2005 E55
Yes, I do see oil leaking — but only after removing the underbody shield. The engine oil collects on the cover beneath the transmission, so it’s not immediately visible on the floor. I cleaned the area several times and drove the car, but the oil kept coming back. I'm in Ukraine and still trying to resolve the issue. The dealer confirmed it's likely the RMS, but they’ll only be sure after removing the transmission.
Member
Joined: Apr 2012
Posts: 97
Likes: 19
From: southern California
'21 AMG GLE63S, '17 BMW 340iGT
The cost to repair mine was close to $20,000, but it was covered by the warranty. About $7,500 of that was replacement of the alternat or-starter and control unit for it, as both were drenched/soaked in motor or oil. That also includes replacing the failed motor and transmission mounts. While they had the engine out, I also had them replace the thermostat, and that cost me $1,500.
Super Member
Joined: Jun 2014
Posts: 517
Likes: 71
From: Los Angeles, CA
2019 S63 AMG (Current), 2015 E63S, 2008 E63, 2005 E55
The cost to repair mine was close to $20,000, but it was covered by the warranty. About $7,500 of that was replacement of the alternat or-starter and control unit for it, as both were drenched/soaked in motor or oil. That also includes replacing the failed motor and transmission mounts. While they had the engine out, I also had them replace the thermostat, and that cost me $1,500.
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Junior Member
Joined: Apr 2025
Posts: 35
Likes: 3
AMG GT 63s
You dont need to remove the transmission to see the leak, just the part where the engine and transmission meet, you'll see the seal leaking. If they do confirm it's the rear main seal, you will also need to replace the OVS else the issue will come back. Good luck, most of us here have gone through the trouble.
Super Member
Joined: Jun 2014
Posts: 517
Likes: 71
From: Los Angeles, CA
2019 S63 AMG (Current), 2015 E63S, 2008 E63, 2005 E55
Junior Member
Joined: Apr 2025
Posts: 35
Likes: 3
AMG GT 63s
Are there any additional recommendations or steps I should take during the repair?How can I properly test the car after the job is done to make sure the leak won’t return?I’m very concerned about this issue and want to ensure it’s fully resolved.
MBWorld Fanatic!
Joined: Nov 2015
Posts: 1,685
Likes: 820
From: Newcastle, WA
2019 S63 4Matic+, 2018 E400 Cabrio, wardens car.
When the OVS units get clogged it actually creates excess vacuum that sucks the seals in, then they leak. You can attempt to change the OVS units but it is a big job because a lot of the front of the motor needs to be removed to gain access to the units. This includes the fan, radiator, charge air coolers and several AC lines. It is not a simple job.
MBWorld Fanatic!
Joined: Mar 2006
Posts: 4,278
Likes: 377
From: San Jose area
'19 E63S sedan
Super Member
Joined: Jun 2014
Posts: 517
Likes: 71
From: Los Angeles, CA
2019 S63 AMG (Current), 2015 E63S, 2008 E63, 2005 E55
Thread Starter
Out Of Control!!
Joined: Jun 2004
Posts: 13,799
Likes: 3,228
2014 E63S; AMS 100 octane ECU dyno tune; EDOK TCU tune; BB intakes; sprintbooster
m256 has its own issues but this isn't one of them so far; this is all plenty discussed in the threads linked in the sticky
Out Of Control!!
Joined: Sep 2018
Posts: 14,666
Likes: 4,568
From: unbegrenzt
2017 GLE350 4MATIC
Most egregious issue with the M256 is deteriorating engine wire harness. It's the mid-90s all over again with Mercedes and dissolving wire harnesses.
Junior Member
Joined: Jan 2025
Posts: 23
Likes: 5
But I don’t want to hijack the thread so back to the RMS issue. Glad that’s not a concern to have for me. Sounds like a real PIA. Looks like most posts here got it covered under warranty but I feel for those that have to pay some serious repair bills. And it sounds like the OVS can clog again, or did they at least update the parts?
Thread Starter
Out Of Control!!
Joined: Jun 2004
Posts: 13,799
Likes: 3,228
2014 E63S; AMS 100 octane ECU dyno tune; EDOK TCU tune; BB intakes; sprintbooster
Already had the harness repair done at 48k, so I guess I don’t have that hanging over me unless it happens again down the line. I’ll be watching it closely though.
But I don’t want to hijack the thread so back to the RMS issue. Glad that’s not a concern to have for me. Sounds like a real PIA. Looks like most posts here got it covered under warranty but I feel for those that have to pay some serious repair bills. And it sounds like the OVS can clog again, or did they at least update the parts?
But I don’t want to hijack the thread so back to the RMS issue. Glad that’s not a concern to have for me. Sounds like a real PIA. Looks like most posts here got it covered under warranty but I feel for those that have to pay some serious repair bills. And it sounds like the OVS can clog again, or did they at least update the parts?
Super Member
Joined: Jun 2014
Posts: 517
Likes: 71
From: Los Angeles, CA
2019 S63 AMG (Current), 2015 E63S, 2008 E63, 2005 E55
