SLK rear subframe

[lanchart]

Not a new subject but a timely reminder for all owners/potential owners of these models. My 2005 very well maintained low mileage SLK55 AMG having had many years of clean annual MOT tests has just been failed on a "Major defect - Repair immediately" due to "serious corrosion and weakening" of the rear subframe near the suspension arm mountings on both sides. My local Mercedes dealer requested that the car be brought in for inspection and advised that there was a known manufacturing problem with internal corrosion on rear subframes on SLKs and that MB were aware of the problem and were replacing these as warranty items. Despite the dealer confirming the corrosion and serious weakening of the subframe (following inspection) and despite having provided service and maintenance records going back many years MB has refused to replace the defective subframe. As a result I arranged for this and with the old subframe removed I have now seen the extent of the failure which is frankly staggering, showing significant corrosion holes and failed welds (pics attached). Nothing was showing on the previous annual inspection by the same testing garage in March 2024 since when the car (always garaged) had only covered 1474 dry weather miles.

 

[Bobby Dazzler]

Not a new subject but a timely reminder for all owners/potential owners of these models. My 2005 very well maintained low mileage SLK55 AMG having had many years of clean annual MOT tests has just been failed on a "Major defect - Repair immediately" due to "serious corrosion and weakening" of the rear subframe near the suspension arm mountings on both sides. My local Mercedes dealer requested that the car be brought in for inspection and advised that there was a known manufacturing problem with internal corrosion on rear subframes on SLKs and that MB were aware of the problem and were replacing these as warranty items. Despite the dealer confirming the corrosion and serious weakening of the subframe (following inspection) and despite having provided service and maintenance records going back many years MB has refused to replace the defective subframe. As a result I arranged for this and with the old subframe removed I have now seen the extent of the failure which is frankly staggering, showing significant corrosion holes and failed welds (pics attached). Nothing was showing on the previous annual inspection by the same testing garage in March 2024 since when the car (always garaged) had only covered 1474 dry weather miles.

How long have you owned the car?

Corrosion so severe is years in the making, so unlikely to be affected positive or negatively by few dry miles in the past 12 months.

Have you received a quote to replace it?

 

[as400]

My local Mercedes dealer requested that the car be brought in for inspection and advised that there was a known manufacturing problem with internal corrosion on rear subframes on SLKs and that MB were aware of the problem and were replacing these as warranty items. Despite the dealer confirming the corrosion and serious weakening of the subframe (following inspection) and despite having provided service and maintenance records going back many years MB has refused to replace the defective subframe.

Eh? they admit there is an issue and are then refusing to rectify?....

 

[DSM10000]

Eh? they admit there is an issue and are then refusing to rectify?....

It's a 20 year old car.

No matter how well maintained it will suffer from degradation of components.

There is a limit to the goodwill any manufacturer will show.

 

[CharlesM96]

A colleague at work had an E class that failed MOT for this reason, 2012 car. Reading around it does seem quite common on a range of Mercs. Did they make any changes throughout the years to the coating / protection level on the subframes? I.e. is there a general period where subframe rusting is more common?

 

[lanchart]

How long have you owned the car?

Corrosion so severe is years in the making, so unlikely to be affected positive or negatively by few dry miles in the past 12 months.

Have you received a quote to replace it?

i have had the car since 2012. As the photos show the corrosion is very severe and localised - the other areas of the subframe look in the condition you would expect of a car 20 yrs old. Replacement cost was just over £4k (did a few other bits while the subframe was off).

 

[lanchart]

It's a 20 year old car.

No matter how well maintained it will suffer from degradation of components.

There is a limit to the goodwill any manufacturer will show.

According to the dealer there was a manufacturing issue with subframes on some models causing internal corrosion hence nothing apparent visually until failure. the pics of my subframe show the unaffected areas look right for age but the failed areas are most certainly not what would be expected of a high performance car produced by a prestige manufacturer. And the failure to issue any advisory or safety inspection recall is in my view inexcusable hence my cautionary advice to other owners to check their cars.

 

[lanchart]

A colleague at work had an E class that failed MOT for this reason, 2012 car. Reading around it does seem quite common on a range of Mercs. Did they make any changes throughout the years to the coating / protection level on the subframes? I.e. is there a general period where subframe rusting is more common?

From posts on this forum it seems there have been pretty widespread concerns on a number of models. Since the problem was identified years ago and since MB has apparently replaced many failed subframes for (99% according to my local dealer) they have presumably rectified the problem on newer models.

 

[lanchart]

Eh? they admit there is an issue and are then refusing to rectify?....

Indeed.

 

[DSM10000]

According to the dealer there was a manufacturing issue with subframes on some models causing internal corrosion hence nothing apparent visually until failure. the pics of my subframe show the unaffected areas look right for age but the failed areas are most certainly not what would be expected of a high performance car produced by a prestige manufacturer. And the failure to issue any advisory or safety inspection recall is in my view inexcusable hence my cautionary advice to other owners to check their cars.

Yes.
It has been well documented here and elsewhere and yes it affects a range of models. A friend has had the subframe fail on a 2014 E Class Coupe, Mercedes did replace that free of charge

Recalls for safety are at the request of VOSA and not the manufacturer though

Plus, we are talking about a car here that is well past it's design life. It made it to 20 years so I can quite understand Mercedes not wanting to contribute.

 

[ALFAitalia]

i have had the car since 2012. As the photos show the corrosion is very severe and localised - the other areas of the subframe look in the condition you would expect of a car 20 yrs old. Replacement cost was just over £4k (did a few other bits while the subframe was off).

Four grand!!....what a rip off....you can buy an after market subframe for under £400.....it not that many hours to fit....I recon I could do one in a day on the ground.

Pardon our interruption...

If my 212 frame goes I'll be doing it myself.....four grand on car that's not worth much more than that is a no go as far as I'm concerned. But if you cant DIY and bought an aftermarket one and got your local indie to fit it there must be a massive saving to be had.

 

[190]

I would argue the subframe failures are a manufacturing issue. It will be down to poor quality steel of too thin a gauge and no internal rust prevention. As for resolving the issue I seem to remember someone commenting that replacement subframes were heavier so thicker steel.

 

[DSM10000]

I would argue the subframe failures are a manufacturing issue. It will be down to poor quality steel of too thin a gauge and no internal rust prevention. As for resolving the issue I seem to remember someone commenting that replacement subframes were heavier so thicker steel.

But, after 20 years.......

 

[Fastcar155]

From my experience subframe failure is difficult to detect regardless of the age of the car.

 

[Petrol Pete]

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[markjay]

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You'd probably want a new one though, preferably the modified item.... no?

 

[Petrol Pete]

I have poked my inspection camera into the frame and seen nothing too bad in there but I 100% agree . I have already sourced all of the bolts and links required for a subframe overhaul , whether that be a new one or a major refurb on the original.