Rust-proof MB Warranty and Treatments Elsewhere

[LGGVW]

Good Morning ,

The MB E250 CDi I have is a 63-Reg, from 2013, so 10 years old. I has no rust at all and MB has a 30-YEAR corrosion warranty, so in theory it has 20 years corrosion warranty left.

Obviously I have been long aware that MB cars used to be prone to develop corrosion in the wheel arches, especially around the curved lip, so I do keep an eye. Just last week whilst washing the car, I passed the pressure jet under the arch lips and lots of wet mud dropped down from the lip fold.

I was surprised because I thought the plastic wheel arch guards created a tight seal with the arch lip fold. Better even, what is the point of having plastic wheel arch guards, if they do not stop water and road salt to get to the metal?... I just don't get it!

I have been thinking about doing a DINITROL corrosion-proof course. Their closest Service Centre for me is in Scotland and they quoted me £700+VAT to do a complete course, which means all wheel arches, the boot well, the under-chassis and the door insides. It takes the car off the road for a full 5 days, so I would have to book some holiday time to get this done.

I am not that excited about the price, nor the long time (5 days) to get it done. Thus I also considered doing the wheel arches myself with the DINITROL DIY KITS and get the Service Centre to do the rest.

But more to the point, there are questions to be made, to which I do not know the answer:

1. I am not sure if doing it invalidates Mercedes Corrosion Warranty!​
2. If I do not do it and rely instead on Mercedes to step up to the plate if the car develops corrosion within the remaining 20-year corrosion warranty, will Mercedes-Benz actually honour the warranty?​
3. If I do the DINITROL treatment (even if it invalidates MB Warranty), would it be a better investment, to avoid a much bigger repair bill if Mercedes does not honour the Warranty?​

DINITROL is good, I know that. It is the approved treatment for all military vehicles at the UK MOD as well as NATO.

What are your thoughts on this, if I may ask?

Kind regards

 

[Bobby Dazzler]

Good Morning ,

The MB E250 CDi I have is a 63-Reg, from 2013, so 10 years old. I has no rust at all and MB has a 30-YEAR corrosion warranty, so in theory it has 20 years corrosion warranty left.

Obviously I have been long aware that MB cars used to be prone to develop corrosion in the wheel arches, especially around the curved lip, so I do keep an eye. Just last week whilst washing the car, I passed the pressure jet under the arch lips and lots of wet mud dropped down from the lip fold.

I was surprised because I thought the plastic wheel arch guards created a tight seal with the arch lip fold. Better even, what is the point of having plastic wheel arch guards, if they do not stop water and road salt to get to the metal?... I just don't get it!

I have been thinking about doing a DINITROL corrosion-proof course. Their closest Service Centre for me is in Scotland and they quoted me £700+VAT to do a complete course, which means all wheel arches, the boot well, the under-chassis and the door insides. It takes the car off the road for a full 5 days, so I would have to book some holiday time to get this done.

I am not that excited about the price, nor the long time (5 days) to get it done. Thus I also considered doing the wheel arches myself with the DINITROL DIY KITS and get the Service Centre to do the rest.

But more to the point, there are questions to be made, to which I do not know the answer:

1. I am not sure if doing it invalidates Mercedes Corrosion Warranty!​
2. If I do not do it and rely instead on Mercedes to step up to the plate if the car develops corrosion within the remaining 20-year corrosion warranty, will Mercedes-Benz actually honour the warranty?​
3. If I do the DINITROL treatment (even if it invalidates MB Warranty), would it be a better investment, to avoid a much bigger repair bill if Mercedes does not honour the Warranty?​

DINITROL is good, I know that. It is the approved treatment for all military vehicles at the UK MOD as well as NATO.

What are your thoughts on this, if I may ask?

Kind regards

How long do you plan to keep the car?

If just a few years then do nothing. If you plan to keep it for 10 years or more then DINITROL (or equivalent) would Eva worthwhile investment, but you’ll never know whether it actually made a difference.

Mercedes will authorise repairs which conform to their terms & conditions, however be aware that it won’t cover all types of rust or corrosion, but that will be the relative minority or cases.

It only applies to metalwork perforating due to corrosion from the inside out, and so even if your car has been inspected every year by a main dealer, if your corrosion is not inside out then they won’t repair it.

If your car has a full main dealer service history and the car is reasonably new then they may repair all sorts of rust and corrosion as a good will gesture, but that is tending to be less and less common.

 

[TeddyRuxpin]

As soon as you spray any of that stuff on your car you can wave goodbye to any MB rust warranty!

It's a modern car, keep an eye out for subframe rust (a different thing altogether), keep it clean and leave it alone... in the life time that you're likely to have the car, it will be fine.

Given that it's a diesel and likely not Euro 6 compliant (?) it's very unlikely that you're going to keep this car for 20 years.

 

[DSM10000]

As above. The MB 30 year corrosion warranty is really not worth preserving as there are so many get out clauses.

 

[ChrisHGTV]

As well as liking Mercs I’m a lifelong Alfisti so quite familiar with Dinitrol! I think their stuff works very well. You may also want to consider ACF50. I stored my Ducati outside for a number of years at my old house and ACF50 kept it completely corrosion free. If you use either it’s worth warming the cans in hot water before use as the products can be quite viscous.

 

[Petrol Pete]

I believe the 30 year corrosion warranty is only valid if the car has been serviced (and inspected) by official Mercedes Benz dealerships , one missed service or a service done elsewhere and the 30 year warranty evaporates into thin air.

My 2006 C55 AMG is showing signs of body rust (pretty much every S203 I have seen in the UK does, there are exceptions) My car at 150K+ miles does not have a full MB service history so I wont even bother taking it to MB.

Adding any type of anti corrossion paint/chemical wil almost certainly invalidate any warranty that might be on the car . I believe that MB have more lawyers and accountants than engineers these days who spend their days at work trying to wriggle out of any responsibility for any of their past engineering mistakes.

JMHO 'natch.

 

[Bobby Dazzler]

My 2006 C55 AMG is showing signs of body rust (pretty much every S203 I have seen in the UK does, there are exceptions) My car at 150K+ miles does not have a full MB service history so I wont even bother taking it to MB.

I follow the Mercedes service schedule to the letter, and it’s all done by the same main dealer, and my W203 was no different - it was spoiled rotten, with anything and everything done by the main dealer.

However when it started rusting at around 8 years old it wasn’t covered because it hadn’t perforated the metal from the outside in. I decided to just get it properly sorted myself and they did a great job.

 

[LGGVW]

How long do you plan to keep the car?

If just a few years then do nothing. If you plan to keep it for 10 years or more then DINITROL (or equivalent) would Eva worthwhile investment, but you’ll never know whether it actually made a difference.

I tend to keep the same car for 3 to 5 years mostly. I would still consider doing DINITROL treatment but just the wheel arches, because that is where corrosion appears first in a large number of cases, by the looks of it.

It only applies to metalwork perforating due to corrosion from the inside out, and so even if your car has been inspected every year by a main dealer, if your corrosion is not inside out then they won’t repair it.

If the paintwork begins to show bubbles, it is going to perforate. Mercedes seems to be short-sighted about this in my view. However, at present my car has no signs of corrosion whatsoever, anywhere. I am just suspicious, after I removed so much wet mud off the wheel arch lip fold (if you know what I mean...).

If your car has a full main dealer service history and the car is reasonably new then they may repair all sorts of rust and corrosion as a good will gesture, but that is tending to be less and less common.

Yes, it has a full MB Service History for most of its life (first registration December 2013), plus MB Specialist garage. Thus at 10 years old, I wouldn't count on MB goodwill to be honest.

As above. The MB 30 year corrosion warranty is really not worth preserving as there are so many get out clauses.

Exactly what I was thinking.

As well as liking Mercs I’m a lifelong Alfisti so quite familiar with Dinitrol! I think their stuff works very well. You may also want to consider ACF50. I stored my Ducati outside for a number of years at my old house and ACF50 kept it completely corrosion free. If you use either it’s worth warming the cans in hot water before use as the products can be quite viscous.

Never heard of ACF50 before. Is it safe to warm the cans up in hot water? How do you proceed, more precisely? How hot should the water be?
I am just thinking the stuff inside expands as it gets warmer, which may pose a risk with the can exploding or something horrid like that?

I believe the 30 year corrosion warranty is only valid if the car has been serviced (and inspected) by official Mercedes Benz dealerships , one missed service or a service done elsewhere and the 30 year warranty evaporates into thin air.

(...)

Adding any type of anti corrossion paint/chemical wil almost certainly invalidate any warranty that might be on the car . I believe that MB have more lawyers and accountants than engineers these days who spend their days at work trying to wriggle out of any responsibility for any of their past engineering mistakes.

I think there is a EU Directive stopping car manufacturers from voiding warranties if a car is repaired elsewhere. I do not think it has been revoked after Brexit, but to be fair I do not k now the full details of the Directive. My car is 10 years old, but only 36K miles or so. No rust so far, I am just anticipating the normal course of events with the wheel arches. Low mileage won't matter at all.

I follow the Mercedes service schedule to the letter, and it’s all done by the same main dealer, and my W203 was no different - it was spoiled rotten, with anything and everything done by the main dealer.

However when it started rusting at around 8 years old it wasn’t covered because it hadn’t perforated the metal from the outside in. I decided to just get it properly sorted myself and they did a great job.

Typical manufacturer/main dealer behaviour. I think it is not just Mercedes. They all do the same.

 

[LGGVW]

Thank you all very much for all the views shared. It is much appreciated.

All in all, I think a full treatment course is probably far-fetched. But I think I might do the wheel arches as a preventative, pre-emptive approach, before it gets bad enough to bubble up the paintwork. At the moment there are virtually no external signs of corrosion at all. It is all smooth and lovely.

The mud I found trapped however, made me think whether these plastic wheel arch linings are actually worse than having the arch clear, thus making it easier for road debris to be washed away. I mean... If the lining does not create a water-tight seal with the arch folded lip, what is the point of having a protective lining?​

 

[BTB 500]

I mean... If the lining does not create a water-tight seal with the arch folded lip, what is the point of having a protective lining?​

I assume it's primarily to stop stones etc. flung up by the tyres from causing damage to the paint/covering on the metalwork.

 

[ChrisHGTV]

Re: warming aerosol cans in water i do this all the time for any paint spraying etc. Just sitting the cans in hot water out of the tap in the sink for 5 mins is enough to reduce the viscosity of the paint/whatever it is you're spraying and also increases the pressure in the can a smidge. You can get a much better spray that way. This is more important as the can empties and the pressure naturally drops. No chance of causing the can to burst etc. Avoid getting water on the cap though! Ive found this is most beneficial for ACF50 which is quite viscous and sticky when cold. Out of the spray can it can come out in a stream rather than a spray if it's too cold.

 

[Bobby Dazzler]

If the paintwork begins to show bubbles, it is going to perforate. Mercedes seems to be short-sighted about this in my view. However, at present my car has no signs of corrosion whatsoever, anywhere. I am just suspicious, after I removed so much wet mud off the wheel arch lip fold (if you know what I mean...).

Yes, it has a full MB Service History for most of its life (first registration December 2013), plus MB Specialist garage. Thus at 10 years old, I wouldn't count on MB goodwill to be honest.

The terms & conditions require that it perforates due to corrosion from the inside out, ie there’s a hole that originated form the unseen side of the panel. Surface corrosion on the outside (which can be sanded back) therefore doesn’t qualify, as it’s subject to stone chips, environmental factors, etc (and is often stated on rejected claims).

If there’s no sign of corrosion now, then by the time it appears then it will be of an age where even the courts would find it difficult to find in favour of the consumer. Not having an annual corrosion inspection performed by the main dealer would void any formal warranty which may have come with you car when brand new, and not using the main dealer for servicing would means there’s no business incentive to offer a goodwill gesture anyway.

 

[LGGVW]

I assume it's primarily to stop stones etc. flung up by the tyres from causing damage to the paint/covering on the metalwork.

There has to be a way of stopping wet mud, salt and road debris from lodging itself between the liner and the wheel arch. The design is flawed in my humble opinion, because the gap is large enough for wet debris to get in but too narrow for the debris to drop down and air circulation dry the space between the liner and the wheel arch. This creates a permanently damp/wet mass in contact with the metal arch above the lining, a recipe for disaster because it will inevitably accelerate the potential rusting of the wheel arch, particularly at the folded lip region.

I think a solution needs to be found to resolve this issue. From a manufacturer's technical point, Mercedes and all others have plenty of AutoCAD experienced engineers able to design a wheel arch liner that overcomes this flaw, and the materials required to seal the gap and eliminate the space between the liner and the wheel arch. Coming from an Oil/Gas & Petrochemicals Industrial IT Engineering, I can think of two or three compressible and hydrophobic insulating materials, suitable to fill the gap all over, between the liner and wheel arch, and a few acrylic "permanent-tack" pastes to create a seal between the wheel arch lip fold and the edge of the liner.

In the interim, I am going to study this in my car, to see if it can be made better.​

 

[Bobby Dazzler]

There has to be a way of stopping wet mud, salt and road debris from lodging itself between the liner and the wheel arch. The design is flawed in my humble opinion, because the gap is large enough for wet debris to get in but too narrow for the debris to drop down and air circulation dry the space between the liner and the wheel arch. This creates a permanently damp/wet mass in contact with the metal arch above the lining, a recipe for disaster because it will inevitably accelerate the potential rusting of the wheel arch, particularly at the folded lip region.

I think a solution needs to be found to resolve this issue. From a manufacturer's technical point, Mercedes and all others have plenty of AutoCAD experienced engineers able to design a wheel arch liner that overcomes this flaw, and the materials required to seal the gap and eliminate the space between the liner and the wheel arch. Coming from an Oil/Gas & Petrochemicals Industrial IT Engineering, I can think of two or three compressible and hydrophobic insulating materials, suitable to fill the gap all over, between the liner and wheel arch, and a few acrylic "permanent-tack" pastes to create a seal between the wheel arch lip fold and the edge of the liner.

In the interim, I am going to study this in my car, to see if it can be made better.​

If you have the ability and materials to make your car just the way you want it, then I wouldn’t hesitate. I would suggest that there’s a reason for not having a perfect seal between the arch liner and bodywork, so there may be a trade off to modifying your own car - fixing one issue may cause another.

If I had to guess I would say that it’s to allow some egress and ventilation because water and moist air (and therefore condensation) will find it’s way in there, and engineers take the view that on balance allowing some water/dirt in has a smaller negative impact than not allowing dirt, moist air and water out easily.

 

[LGGVW]

If I had to guess I would say that it’s to allow some egress and ventilation because water and moist air (and therefore condensation) will find it’s way in there, and engineers take the view that on balance allowing some water/dirt in has a smaller negative impact than not allowing dirt, moist air and water out easily.

Good Morning Bobby

I thought about that as well, thus I agree with your comment. Hence the need to study the wheel arch setup. I haven't done so in detail, so I don't know.

What I do know is that the liner is separate from the coachwork wheel arch panel which has the arch inside lip folded upwards. The gap lets mud collect on this fold, it stays wet.

 

[LGGVW]

I think I will take photos when I get to study the issue, to illustrate and if possible I will provide photos of the solution adopted.

But I suspect that once the liners are removed, the whole 4 wheel cavities arches will have to undergo:​

1. Full wash with a capable and efficacious degreaser, like Bilt Hamber - Surfex HD;​
2. Rinsed after de degreaser with a steamer;​
3. If any loose rust present, it will have to be brushed off with a stiff brass brush and then steam-rinsed again, and then let to dry;​
4. Apply rust converter and when that is set and bone dry...​
5. Prime and paint with rush inhibiting primer and paint, 2-in-1 probably good for this;​
6. Finally DINITROL, making sure the inner arch lip fold is well covered; if it is to be left with the gap it came with from Mercedes.​

The wheel arch liners themselves:​

1. Full wash both sides of each liner with the same degreaser, I mentioned Bilt Hamber - Surfex HD because I know it so well. I use it to wash prior to detail the engine bay;​
2. Rinse the liners with a steamer both sides of each liner and let dry;​
3. Spray the outer face of the liners (therefore the side facing the wheel arch cavity) with a suitable product, maybe ACF50;​
4. Re-mount the liners.​

The process should allow me to gauge how wide the gap is between the liner and the bare wheel arch and indeed if there are sensitive components attached to the bare wheel arch or whether it is just metalwork. Another question is whether there is a draining opening between the liner and the wheel arch at the back end, to both sides of the suspension sub-assemblies. If there is, it may be possible to insert a standard hose pressure sprayer to force out any debris entering the gap, as it would theoretically run through to the back.

It is going to be messy, no doubt. ​