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My subframe is rust out 2010 c300 4matic sport 94k miles
Hello, just got word from my indy mechanic that my subframe has rusted in half. Bringing to Mercedes to have it looked at. Hopefully they will cover the replacement. Do you think they will cover it no questions asked, its making a clunking sound and back end slides out when braking hard. @TimC300 Hey Tim, hope you are well. I remember you helping me out a ton 2 years ago when my C300 was hit.
Your car is 16 years old and has 94,000 miles, why do you think they would cover it? At max, many car companies only cover powertrain for 10 years, not body. (Note, this does not count recalls on certain safety systems, like they did with some of the SBC modules covered to 25 years).
2023 E 450 Sedan. 2018 GLC 300. 2013 E 350 Coupe (retired)
Extended warranty from internet search:
Mercedes-Benz has extended the warranty on rear subframes for specific C-Class models (W204, 2008–2015) to20 years with unlimited mileagedue to corrosion issues, particularly in cold-climate regions. The, often free, replacement is valid if the subframe has structural damage like holes or broken welds, as confirmed onthis Mercedes-Benz NHTSA documentandthis related NHTSA document.Key Warranty Details:
Coverage: Covers the rear subframe and its mounting bolts if perforation (holes) from rust is present.
Models Included: Primarily 2008–2015 C-Class (W204) and 2010–2015 GLK-Class (X204).
Models Excluded: The newer W205 (2015–2021) C-Class is typically not covered, despite similar rust reports.
Action Required: Contact an authorized Mercedes-Benz dealership to have them perform a safety inspection using your Vehicle Identification Number (VIN).
Hey the dealer quotes first then go from there.
It's very possible it's covered butt they take they timer on the repair at three dealer so it could take weeks or more to get them to fix it.
Looks "perforated" to me, Frame looks rusted and split at least in the photo.
I would print out all the warranty information for the subframe and bring it with you to the appointment with the dealer. They will inspect it then provide you a write-up of what they observed and recommend.
Ask for a detailed quote of everything they plan on doing. From my understanding from what others have said the subframe replacement includes all new bushings in the subframe itself. I think the new subframe comes with the new subframe bushings and differential bushings already installed. They should use all new hardware.
In my opinion this is a good time to have any worn control arms, sway bar, even rear passenger brake line replaced if it needs it. They will probably bill you for that work but with the subframe already off the time should be significantly less. My local MB dealer will even install parts I supply.
Though i'm sure they will try to charge you $2K to replace the rear brake line since they will want to replace the entire line from the engine bay back. You can easily replace the line yourself if needed. I did the rear section of mine for under $100 in parts.
Even with regular inspections and no noticeable signs of perforations mine broke. after a bad winter driver side thrust arm separated. I’m guessing the years of fluid film I was putting on just masked the outside and it rotted from inside. Poor quality part that should be replaced as it ages, should be a recall.
Brought it in this morning, they said it will be ready sometime tomorrow and it is covered under the extended warranty. they recommended almost 5k in other work which i deferred but hopefully no surprises and it will get done completely free.
@TimC300 Good news, they are fixing it under the extended warranty and will be done sometime tomorrow. They recommended that I do my brake lines for $2700 but I declined. Also said I was leaking a little tranny fluid and wanted to do the filter and fluid for 900. Brake lines do look pretty rusted but I am going to wait. Tim I know you have a very similar model to me, have you done your brake lines and if so when? How's your car running, any major issues lately?
I will say, I was a little nervous about the whole situation and thought they might give me a hard time but so far their service has been first rate. They've made it very easy.
Your car is 16 years old and has 94,000 miles, why do you think they would cover it? At max, many car companies only cover powertrain for 10 years, not body. (Note, this does not count recalls on certain safety systems, like they did with some of the SBC modules covered to 25 years).
As posted, this is an extended warranty with unlimited mileage and thats why the Op would ask if it's covered. Do you believe a frame defect allowing the frame to break in half is less of a safety issue than brakes.... Perhaps read up on reality before providing a false narrative. any amount of research would have provided you that answer. Sbc was and is not a recall and started with a shorter covered extended warranty term and it kept getting extended as more problems came to light. Initially it was a reprogramming, and turned into full replacement covered to 25 years, the expected life of those cars. Remember that these extended warranties are the result of a negotiation with NHTSHA so that they dont have to do a recall.
@TimC300 Good news, they are fixing it under the extended warranty and will be done sometime tomorrow. They recommended that I do my brake lines for $2700 but I declined. Also said I was leaking a little tranny fluid and wanted to do the filter and fluid for 900. Brake lines do look pretty rusted but I am going to wait. Tim I know you have a very similar model to me, have you done your brake lines and if so when? How's your car running, any major issues lately?
I will say, I was a little nervous about the whole situation and thought they might give me a hard time but so far their service has been first rate. They've made it very easy.
I saw SS brake line online, wonder if anyone installed these here. Mine are rusty at just the ends where they meet the brake hoses, but have been looking ok for the last few years with fluid film, I was acutely able to remove the brake hoses last year without breaking the lines off. I did have a leak under the driver seat that I fixed.
I replaced the rear section of my rear passenger brake line. It was severely rusted from the drivers side wheel well over to the passenger side so I simply cut and spliced in the new section.
It was inexpensive to do. I think the specific brake line flaring tool was the biggest cost. I highly recommend using the Genuine Mercedes nuts and connectors.
I think I really lucked out because as I was working on the brake line the old line started leaking.
UPDATE: I brought my car in Thursday morning for the subframe and airbag recall. They "fixed" both and I went to pick it up Saturday and the car won't start. They said my ESL failed and needed to fix it for $2700+ plus a new battery $475. I did not want them touch my car after that, as its been my daily driver for the last 5+ years and never not started. Apparently the airbag recall commonly causes the ESL to fail b/c they disconnect the battery and when they reconnect it, it sends high voltage or something. I had it towed home. Now my steering wheel is locked. I replaced the battery but nothing. Anyone have any advice on the ESL, I heard about an emulator? Anyone know someone that can fix this in the Boston, Massachusetts area? Thanks @TimC300 have you had your ESL lock up before? Also, did you have to bleed your break lines and how did you fill them?
Last edited by Boston M Benz; Apr 26, 2026 at 01:15 PM.
I never worked on the ESL before. If it is just the blown electric motor I would try replacing it. Seems the big issue is removing the ESL since its in the locked position. Will have to research how to remove it.
I replace the brake fluid every 2yrs. My brake fluid will turn a dark brown color or at least not as clear as new fluid. I bought an inexpensive bleeder and it works great.
I buy the MB Dot 4+ brake fluid on ebay pretty cheap. A 1 liter container is plenty to do the job.
- Use tape to mark the level of brake fluid in the reservoir. You want the level to be the same when done the job. (unless replacing brake pads and rotors)
- Open brake fluid reservoir and suck out as much old fluid as possible. Fill to the top with new fluid.
- Fill brake bleeder with rest of new brake fluid. Connect bleeder to reservoir. Pump up bleeder to 10-15psi.
- Open bleeders at each caliper and allow the fluid to run into container until you see the new clear fluid then close bleeder. I use 1/4" ID tubing on bleeder to container. Torque bleeder screw 14nm.
- Release pressure on brake bleeder and remove from reservoir. Correct fluid level in reservoir to original level.
ESL stuck in the locked position is a pretty hard job, you have to take the steering column out. The dealership broke it after they did the airbag recall b/c their notes say they test drove it after the subframe was put in and it drove normal. Either way, now I need to get it fix and I think the emulator is the way to go. Does anyone know someone in the Boston, Massachusetts area that does emulators? Man this sucks.
Based on your user name I’m assuming this is a mass car, the salt the state uses is brutal on these cars. I highly highly recommend you do a yearly or bi yearly undercoat. Obviously doesn’t help you when the frame is gone but with the new subframe you can at least protect it for years to come
ESL stuck in the locked position is a pretty hard job, you have to take the steering column out. The dealership broke it after they did the airbag recall b/c their notes say they test drove it after the subframe was put in and it drove normal. Either way, now I need to get it fix and I think the emulator is the way to go. Does anyone know someone in the Boston, Massachusetts area that does emulators? Man this sucks.
Last resort, try to tap the esl directly with a hammer while turning car on, long shot but may work one more time.
From reading it i would try to replace the electric motor. Wont have to mess with finding and paying to have e new ESL coded or an emulator coded.
One very important step i read was to make sure the ESL is in the SAME position as it was when hooking the battery back up. Something about the car counting the exact number of thimes the car is locked/unlocked and if reinstalled wrong it can screw up the car.
I would try the step noted above tapping the steering column trying to unlock the ESL.
Your car is 16 years old and has 94,000 miles, why do you think they would cover it? At max, many car companies only cover powertrain for 10 years, not body. (Note, this does not count recalls on certain safety systems, like they did with some of the SBC modules covered to 25 years).
So, MB USA extended warranty coverage for rear subframe rust through….
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