Corroded rear subframe

[John]

Your subframe is clearly rusting and has been like that a long time. It not being mentioned before to you is nothing new as it depends who does your MOT and works on the car - which can vary each time and from the person looking at the car now.

Since you have emailed MB, you could try for a FOC replacement based on the above advice.

I'd be surprised if they offer to cough for a new part. I've only had success on non-warranty items when you are there in person and you are speaking with the service manager or similar. I doubt they would do anything in writing.

Given your car is in with the garage now, I would get a quote from MSLP in Birmingham for the same work (rough estimate over the phone) and compare to the quotes you already have.

You then need to decide if it is worth repairing or not against the car value.

I wouldn't automatically write the car off if the bill is close or more just on that basis. I would base it more on how much you like the car, how reliable it is and whether it still does what you need and whether or not there are any other big bills looming through scheduled maintenance / tyres etc.

If it is worth continuing with, then compare the costs between the two (factor in the cost to put your car back together so you can take it elsewhere) and decide from that.

 

[Petrol Pete]

OP , keep pushing MB for a FOC replacement , even if they don't agree but come down in price it's a kind of a win. Ask them to show you where on an A,B or C service the rear subframe is mentioned . There will be all sorts of references from engine oil all the way down to the key fob battery needing to be replaced, but I suspect very little specific to the rear sub frame.

As for them bringing up the bodywork anti corrosion warranty and bundling the rear sub frame in there ...hilarious. Keep on pushing , do more research. Good luck.

 

[Skd884]

Have a look here some folks had it replaced FOC -

Rear Subframe for a W204??? | Parts, Maintenance & Servicing

Did you fit it yourself? No i had the garage fit it but it was fitted in the same day they told me it wasn't a hard job

forums.mbclub.co.uk

 

[Fastcar155]

Hi , I have been chactised on this forum regarding rear sub frame failure.

How can I car that car been MOT annually suddenly have a failed subframe?

Does your car have a service history again I would question how good has the servicing been?

I am not sure if an under body inspection is part of the service on your car but as it is a know issue it should be.

I had my 6 year old car inspected for brake line corrosion and rear sub frame issues.

Car was as new in the checked location.

However , I should mention that apart from the first year the car was not used in a UK winter as I have wintered the car in Portugal in the other years ( C19 issues put to one side )

What I tend to do is throughly underneath using a lawn spray ( got to get the underneath really in the first place )

Hope that Mercedes sort out the problem to your satisfaction.

 

[drmacf]

Any ideas or theories on why MB cars, specially C class, have corrosion issues?
I read somewhere that it may be due to inferior metal they started to use, imported from China.
I grew up thinking that Mercedes was the gold standard in reliability and was like a bullet proof car. Now looking at those pics, I shudder to think that just a couple of days ago I drove down the motor way with my daughter in the backseat!
May be the C in C class stands for C-orrosion

 

[190]

To be fair general corrosion on recent MB's has been tamed by galvanising vulnerable panels and I've no doubt that W204's will be getting scrapped due to big repair bills but still with perfect bodywork. The obvious question is why on earth didn't they galvanise the sub frames.

 

[grober]

Any ideas or theories on why MB cars, specially C class, have corrosion issues?
I read somewhere that it may be due to inferior metal they started to use, imported from China.
I grew up thinking that Mercedes was the gold standard in reliability and was like a bullet proof car. Now looking at those pics, I shudder to think that just a couple of days ago I drove down the motor way with my daughter in the backseat!
May be the C in C class stands for C-orrosion

The answer is probably multi factorial as always. Your remark about Chinese steel is reminiscent of the criticism levelled at Mercedes cars of the late 90s who suffered from body rot. On that occasion it was blamed on inferior Russian steel. Mercedes are fairly unique in so far as they are rearwheel drive and the rear subframes are more complex than most frontwheel drive cars whose rear suspensions are normally a beam beam with struts attached.
You can see the appeal of complete pre-assembled sub assemblies such as rear subframe/differential/suspension units to the mass production line in that the body can be lowered onto such an assembly and attached by four bolts thus speeding up the line.
So we start with a fairly complex sub-assembly which functions to feed multiple suspension loads into the main body of the vehicle and as such is full of angles nooks and crannies and hollow steel sections ready to trap moisture and road mud -- a recipe for corrosion--- perhaps they figured they could get away with thinner gauge steel to reduce weight leaving little leeway for corrosion to weaken the structure who knows------ rust protection seems to have been minimal quick paint dip and little else. As previously remarked greater attention to rust protection such as galvanising and drainage would certainly have slowed the corrosion process to acceptable rates.
I'm sure the engineers knew all this but I sense the presence of "spreadsheet cost reduction man" may have also had a role to play.
What price reputation??

 

[st13phil]

Good analysis by @grober, above.

The common feature of all the W204 rear subframe corrosion stories we've seen on here is that the first indication of it is catastrophic failure when it has become so weakened by corrosion that it physically breaks. This is important because it is not being picked up by MOT inspections, presumably because either the corrosion is primarily internal or alternatively it occurs in an area that cannot be seen / inspected.

My gut feel is that Mercedes willingness to replace the failed component FOC even on quite old examples is at least in part because they don’t want to be on the end of an expensive safety recall campaign.

I've suggested before on one of the earlier threads that when an owner gets the brush-off from a dealer then it could be worth gently making the suggestion that the owner is considering taking up the matter with the DVSA as a serious safety matter. If my hunch is right, then that would concentrate minds on getting it fixed without expense to the owner.

 

[GP801]

The guy who does the MOTs on our 171 and 209 says they rot from the inside out. Water and dirt gets trapped inside and there are no proper drain holes. He says almost impossible to spot until its too late. He encouraged me to take along a can of Dinitrol or similar rust protection and he sprays it inside the frame as best he can whilst doing the MOT. Fingers crossed but so far so good.

 

[drmacf]

Are there any lab, where I could send the sub frame for testing?

 

[whitenemesis]

Only parts that need an inspection from time to time, done under the MOT not Mercedes. A Mercedes service history would prove you have had the oil and filter and other filters changed, it would not prevent the rear subframe from corroding.

Mercedes service also includes a general inspection of the bodywork and suspension and in theory at this this should be identified well before becoming a safety issue. Now, whether these inspections actually get done is mute but the point being had the OP a full dealer service record MB would find it hard to wriggle out.
They (MB) have recognised the car had an MOT just months prior and nothing advised, so will simply point to inadequate attention to service/maintenance. Anything not done 'in-house' is simply beyond their control and responsibility

 

[grober]

Are there any lab, where I could send the sub frame for testing?

Any university engineering department specialising in metallurgy could do this----for the price of a replacement subframe! ! -then what?
Face it the car is 12+ years old---all cars manufactured from steel rust -some faster than others and depending on climate -Mercedes are pretty much par for the course

 

[drmacf]

Any university engineering department specialising in metallurgy could do this----for the price of a replacement subframe! ! -then what?
Face it the car is 12+ years old---all cars manufactured from steel rust -some faster than others and depending on climate -Mercedes are pretty much par for the course

Thanks Grober
all cars manufactured from steel rust
Though, I don't think this is the feedback I read, on most MB forums. If this was inevitable, why would MB pay to get them replaced? Why not just say what you say, 'tough luck, 5hit or rust happens'

 

[MrGreedy]

I don't think 'Chinese' or 'Russian' steel is the culprit, whereas if they had used 'German' steel or another nation everything would be fine. Are we talking about the location of the ore mined? The ore processed into basic steel? The point of refining? The recycling of scrap steel and remelting and refining into 'new' steel? Or the location at which the steel was rolled into sheet.

In any event, regardless of the 'location' that the steel has come from, steel body panels are all low alloy steel, and regardless of how 'good' the steel is (by which specifically I mean cleanness and alloying additions), all low alloy steel will rust and rot away without additional protection. The steel does not have high chromium or nickel content, so rusting away over time is going to happen. This can only be stopped (slowed) by the application of a suitable coating. It is these coatings that are inadequate, combined with poor design and therefore the ability for muck to linger and act as a sponge, retaining moisture, that is the culprit.

That is the responsibility of Mercedes, and anyone pointing at xyz raw steel manufacturing is kind of missing the point in my view.

 

[grober]

As with red paint blistering/bubbling issue- your chances of replacement FOC by Mercedes is very dependent on any owner's previous relationship with any MB dealership. If you purchased car originally and have had it serviced religiously by MB then your chances of a FOC repair will be much higher--- a cynic might say that by paying "over the industry odds " MB service costs for many years you have already paid for such a replacement. Moving outwith the MB dealership envelope and multiple owners finds you on a much stickier wicket. not trying to excuse it but that's just the way it is

 

[Tonygw]

Mercedes service also includes a general inspection of the bodywork and suspension and in theory at this this should be identified well before becoming a safety issue. Now, whether these inspections actually get done is mute but the point being had the OP a full dealer service record MB would find it hard to wriggle out.
They (MB) have recognised the car had an MOT just months prior and nothing advised, so will simply point to inadequate attention to service/maintenance. Anything not done 'in-house' is simply beyond their control and responsibility

I agree of course, but surely, they should recognize they have fitted "sub standard" parts from new. Service history or not. the parts were not up to the required standard. This is in fact a safety concern, yes it should have been picked up on an MOT or even a service maybe. But they should reconize and in some way provide compensation for selling a product which doesn't meet the required quality standards.

After all, Lesser/ cheaper brands do not in the whole suffer with such issues.

 

[whitenemesis]

I agree of course, but surely, they should recognize they have fitted "sub standard" parts from new. Service history or not. the parts were not up to the required standard. This is in fact a safety concern, yes it should have been picked up on an MOT or even a service maybe. But they should reconize and in some way provide compensation for selling a product which doesn't meet the required quality standards.

After all, Lesser/ cheaper brands do not in the whole suffer with such issues.

Perhaps lesser/cheaper brands succumb to other failures well before 12yrs? (slightly tongue in cheek comment )
It would be interesting to know the percentage of these model/year that suffer subframe failure. We obviously hear the worst on forums.
As for a 'sub-standard' part, it must have complied with design specs with regard to structural integrity. Longevity is always more difficult to specify as much of the parts exposure is beyond control (coastal areas, those countries with heavy salted roads etc..) so this where the dealership service inspection would come in. To monitor and hopefully detect early on any degradation. If found quite probably it would be replaced FOC. A vehicle presented after 12yrs with little current dealer history is going to be hard to justify but who knows?

 

[DrNick]

The reality is its a 12 year old car with an uncertain history. I'd be surprised if you got anywhere with Mercedes under those conditions and I wouldn't even try.
I'd be getting a few quotes from local places and biting the bullet if the rest of it was in good condition.

But that's just me (and I have successfully hassled MB for body repairs previously)

 

[drmacf]

Thanks to all who responded, it really helped me.

Just an update, from my side. MB Lincoln have basically said to pay up for the replacement and get the job done. When I refused, they have stopped replying to my emails.

The car is currently at an Indy Garage, who have ordered the sub frame. No exact time frame has been given on when it would arrive and the job be done. Costs wise it will look like the subframe is 695 + vat and labor around 600 quid. Will be out of pocket for about 1500-1700. Tough luck, but I like this car, so will hang to it.
Currently renting out a Ford 500 from Euro Car, hope its sub frame is intact!

After this is all over, I would make a complaint to the DVSA. Not sure if it’s worth but just for the record would write to them. I would also open a FB page about this MB C Class or Corrosion class and collate all the information available, both on line and on MB forums. I have come across at least 100 posts, some going back to 2004! So there is something out there. At the least, if people are informed, then they might pay more attention to details, such as getting the mechanic to check the underside more vigorously as well as taking anti rust measures. Something which in hindsight I would have done.

Another thought I had, was to get the car up on a ramp and spray the underneath with ACF 50. I have been warned not to use it on the brake pads and liners. About the engine, I could spray some on a piece of cloth and lightly wipe it around. Hope this is the right way as I can no longer rely on the MB brand name.

Thanks once again

Have a lovely bank holiday weekend



Mel

 

[Trickythemerc]

What is a Ford 500