My 2010 ML 350 (on the road Dec. 15, with less than 900 miles so far) has pitting corrosion/rusting on the metal trim on the door side panels and the rear bumper (both the luggage protector strip on top of the bumper, as well as the one on the lower part of the rear bumper - don't see any on the front bumper protector). This after only driving a couple of times in the past couple of weeks through snow cleared/de-iced roads in a small town in Northern Colorado.

Noticed the rusting after a few days of driving on the snow cleared roads and then it being parked in the garage. (I use a smaller car for most of my in-town driving)

As a corrosion prevention engineer, I see the reason for this rusting as the metal trim not being resistant to the road de-icing salts getting on the trim while driving through the slush.

Never had this problem on my previous (2008 E350 ) car that I turned in when I got the ML, after driving in similar conditions for the two winters here that I owned it.

So my questions:

1. Anyone else experienced this kind of rusting?
Forum search on "corrosion" only got a hit on corrosion problem with alloy wheels https://mbworld.org/forums/newthread...newthread&f=72 (post 13, 19, & 26)

2. Is this a problem with the metal trim not having a special coating ? (lacquer? as mentioned in the above referenced thread for the alloy wheels)or below spec chrome/steel used? (e.g. Type 314 stainless steel pits when exposed to salt sprays, Type 316 is more resistant and the one usually specified in marine environments)

3. Is it just a bad batch of trim that ended up on my car?

4. Any ideas on how to prevent this? (other than washing down the car after every time I drive it on de-iced roads)

Plan to take it down to the dealer next week to have it looked at, but would like to be prepared as much as I can be with feedback from the forum.

@VelociRaptor - has anyone at the factory heard of this being reported?

Right now I've washed off the pitting corrosion/rusting as I didn't want it getting worse just sitting there. Can still see "stain" marks where the pitting/rusting had started, but none that will show up clearly in pics now. Will post pics once the rusting shows up again (and it will, now that it's started!)

Thanks in advance.

 

l've had some issues' with some items on my previous M-Classes, such as lug bolts rusting and it was replaced under warranty....l just purchased my M-Class in October and will take a closer look at those areas...To be honest, it doesn't surprise me, the M-Class in made in the States and l'm assuming some of their supplier's are so-so at best... as compared to your E-Class which was built in Germany....Keep us posted....l'm assuming, if it is happening to you, it will happen to me, as l live in an area of considereable snow as well....

 

There was someone else post about some rust on the liftgate and I asked for some pix so I could see what exactly it was and dont think any was posted. We as employees at the plant do really have any feedback like that at work. We do get feedback but were I work(on the trim side) we get feedback on fitment of the interior.
BTW, Im working this year on a new line. Im still installing hardmarks(main reason why I was moved, because that process was moved) but installing carpet, gas pedal, closeout panel and lower pillar trim(and some more odds and ends).

 

Last winter i had to make an unexpected and extended trip to europe and in the hurry of it all i forgot to wash the ML before i left. It had a serious coating of salt and when I got home and took it to the car wash i saw that there was serious ''looking '' black stains and what i thought were tiny pits on all the trim pieces. Needless to say, I was pissed off but decided to try some metal polish before i went to the dealer. Much to my suprise, all the damage was cleaned off with perhaps 20 mins of elbow grease and things returned to as new look and shine.I was amazed at how much black crud came off as i used the metal polish and since then I rub the trim down with the polish on a regular basis and after 2 plus years( and 2 winters in a salty winter climate) its still looks great. Now, since I can't see your trim, i can only guess as to how bad yours is, but i thought mine was trashed and it turned out to be a minor problem so I hope that for the expense of a bottle of some good metal polish and a few mins of your, or perhaps your detailers, time, things go back to normal. Its worth a try before you go to the dealer.

 

The chrome strip on the rear bumper (luggage protector) is....ABS plastic...no chance of rust there. It could however have defects in the coating used, if thats the case it would be replaced under warranty for free.

 

no problems with my 2010 ML350 and it has been covered in salt and snow recently from some storms in our area. I try to regularly wash any salt and dirt off the car during the winter time. when you wash your car, does it seem like there is still wax on the car? i'm wondering if the corrosion might be from a defect as mentioned above.

 

I had the rusting spots on the metal skid plates of both the front and rear bumpers on our 2009 Ml350, particullarly the bolts that hold this skid plate, around them there was rust marks/stains, as well, we have the optional running boards and they became tarnished, I had everything replaced under warranty, apparently the service manager said that this is not the first time they have done this type of warranty work. I think it is the actual alloys used, because, now with another winter well under way and with frequent driving in salty slushy conditions, the new parts which were replaced in the spring seem to have the same symptoms, so I will wait until the winter season is over and get them replaced under warranty once again.

 

Thanks all for the feedback. This will really help with my visit to the dealer.

I'll keep you posted as things progress. Will also post pics once the rust spots come back.

 

try a clay bar on these "rust" spots.

 

Talked to a SA at the Denver dealership while making the appointment to have them take a look at it, and got the following:

- "Mercedes does not see this as warranty issue in Colorado as they use magnesium chloride for de-icing here, so will not replace any corroded trim under warranty"

- When I mentioned one MBWorld poster had these replaced under warranty the response was: "May be replaced under warrany if it is an extreme case and then only one time"

- When asked what they recommend, was told "Use a chrome polish to remove the stains and then put a coating of carnuba type wax on the trim" (said they will sell me this polish, with, I guess, the expectation of me taking care of this problem in the future)

So what I understood is that when I go for my appointment, they will polish and wax the trim one time for me, so I know what to do in the future.

My thinking is that since mine is a lease (rental) it's really MBs problem because of product quality issues, and at the very least I'm covered under the "normal wear & tear" for the conditions here.

There was no reponse to my observation that my 2008 E250 did not have any such problem in the two winters that I drove it here. I will make this point again when I see them, and also ask which vehicles they do see this problem on which ones they don't (Mybe C-rod has a point re German made vs. US made ).

 

Wow, they have mastered the art of gab at MB! Have an eloquent answer for everything!
I live and drive a lot in the Chicago area, and salt is put down by the truckload at the first hint of snow. So far, the only rust colored stains I have noticed is around the bolts that secure the front skid plate. That usually polishes off in the Spring. For now, I frequently use a car wash that offers undercarriage wash and "rust inhibitor"(?), and so far I have no issues.

Now if there is an easier way to remove the salt stains from the interior carpet around the edge of the mats I would love to hear. Took over 2 hours of scrubbing last Spring and the salt stain was just starting to budge!

 

What a crock....I had one of the running boards that had some sort of stain in the metal, like it was tarnished and i used many products to see if i can remove it myself, when I couldnt, I showed the service advisor and they ended up replacing both running boards as they come packed in pairs, as far as the skid plates, again, they replaced them both(front and back) ESPECIALLY since your car is so bloodu new, I would talk the sales manager as they could pottentially loose a customer in the future, this usually ruffles the feathers of the service department.

 

I'm going to back up from this statement. The luggage protector on my R class seems plastic, so I assumed they switched over.

 

Went down to see the SA last week. Turned out to be a non-event in more ways than one.

Soon as I walked up to the counter and told them what I was there for, I was told again that as far as MB was concerned it was not a warranty issue so were not able to do anything about it other than to advise me to put a chrome polish on it.

On my insistance the SA came out an looked at it and said yes, although they see a lot of rusting on the ML trim, per MB it was the customers responsisbility to ensure it doesn't rust.

When I asked how come my '08 E350 never had this problem under similar driving conditions was told that MB uses different metals on different vehicles.

Since it was obvious the SA wasn't going to do anything else, I asked for the visit to be logged so that it least it would be on record that I had come in to report the problem. I was told this would be done bu t2 days later I got a call from the recepcionist telling me that in her records "I had missed the appointment"! Turns out since the SA did not make out a repair order the appointment computer did record the visit, although I was still asured that the visit was recorded in the SA's computer (weird!).

Anyway, I followed a previous posters suggestion and went to see the Sales Manager and left a copy of these posts for him to discuss with the Service Manager.

So that's where I am for now. The rust stains are still faint from when I had cleaned up the trim with soap and water. We haven't had another snow storm here since so we'll have to wait and see what happens next time the trim is exposed to the road salts. If there rust & stains bad enough that will show up in photos I'll post those and also escalate this up directly to MB Customer Service.

 

Just clay the panel.. takes 5 minutes and saves the dealer headache.

 

Actually the magnesium chloride is the culprit. This stuff is wicked. It reactivates everytime it gets wet and continues to eat away at metal. All it takes is for this stuff to lay in crevices near bolt heads or any little nook or cranny and as soon as it gets wet it starts to corrode metal.
Even washing the car starts it up again.
Ask any chrome wheel seller or manufacturer and they will tell you the same thing. It is like trying to get a fender warrantied that you have spilled brake fluid on.
Magnesium chloride goes way beyond salt in it's damaging corrosion capabilities.
Remember that dealers have a certain amount of "goodwill" warranty available to spend each month and maybe the person that was taken care of got thier items replaced that way.
If you live in a climate that does use this chemical the best thing you can do is go through a high pressure wash with under body spray.
Google it and read some of the horror stories associated with magnesium chloride.

 

Hello Chaps. You think you have problems. I have rust creep under the paintwork on the inside of the bonnet ( Hood ) Tailgate and rear nearside door.

All the rust is eminating from the join at the seams of the panels. Merc Uk have agreed to replace the door, tailgate but not the bonnet as they say it can be repaired and the rust stopped. I purchased and endoscope camera and took some photos of the rust creep under the primer in the bonnet between the panels. Nerc Uk say these are inconclusive. I bitter pill to swallow. I am still argiung with Merc UK but hitting my head against the corporate brick wall. So ML's do rust. Mercedes have not over came the rust issue. I would be interested in the comments of the threadstarter given his credentials.

This is only where I can get the camers in. Its on the drivers side ( UK ). On the outside of the bonnet it is rusted under the paint the total length of the driverside. It has been rusting under the paint and primer since it was built. A bit of a disgrace for a £44000 car when I bought it. Thanks.