do you think that the hood can in these places corrode?

 

Hi Paul, With our Canadian winters it's sure to rust, the only question is how long it takes to rust out.
The metal surfaces are close together but not touching therefore without proper drainage, as is the case, all "B" class will be affected until they change the stamping at the factory, before the 2 hood pieces (bonnet) are pressed together.
The paint is good so the rust won't happen overnight, but it will make for a lot of unhappy "B" owners in the future.
My dealer was amazed when I showed him the hood. I can't imagine how this defect wasn't spotted during the designing stage.
In the near future I plan to install my own bonnet insulator and this will reduce the chance of water getting in. Time will tell !

 

In the near future I plan to install my own bonnet insulator and this will reduce the chance of water getting in.Time will tell !

I would like to install an insulator as well but I wonder if this will cause too much heat to build up.

 

Hi, could you please include any photos for this case?

Thanks!

 

I think an insulator is installed to prevent excessive heat from reaching the exterior painted surface of the hood.
It also reduces sound from entering the passenger compartment and reduces splashups from tracking inside the hood.
Heat should dissipate quite well due to the fact that the motor compartment is open to the ground in many areas when looking down .

The holes are there for the insulator, why didn't they include one ?

 

. The holes are there for the insulator, why didn't they include one ?

Another cost cutting exercise probably.

Regarding the bonnet drainage would it not be possible to fill the offending part with something like Waxoyl (a liquid semi hardening wax) as by drilling into the bonnet you are actually baring the metal which in turn could lead to rusting.
I understand your concern & your resolution to the problem but how would M/B respond ( under the anti corrosion warranty) to a bonnet that had been drilled & subsequently had rusted, would they blame the drilling for the rust problem ?

 

The best solution is proper drainage.
I've done this by drilling a few small holes. There are a lot of little details I didn't include in the first posting.
Where the drill bit penetrates the first sheet of metal, primer and painting with a little brush is recommended followed by proper drying and hardening.
Your wax idea is good. The cavity protection spray I used is sold at the MB dealer (Part # A 000 986 33 70 10 ). It comes with a long nozzle which I tracked deep into those same holes and liberally sprayed every place I could find on that hood (bonnet).
Another product is by the Wurth company also of Germany, Part # 0893.081-A and is also a cavity wax used on Audis.
Our 'B' has a great application of cavity wax from the factory, but is mostly applied to the underbody, but we can always improve on it.
I've also done a lot of touch ups by brush with the same products purchased in a non spray form. Filling the trapped area with wax might work, but I won't chance it.
We live north of Montreal, and we live with 6 months of salt spray on our highways. I figure 1 salt season is equivalent to 10 rainy seasons elsewhere and I'm not too worried about the MB rust warranty because I don't know anyone whose ever collected, do you?

If anyone attempts to drill, you must stop the drill bit from touching the 2nd sheet of metal by sliding a mylar strip of insulation down into the offending cavity before you attempt to make this hole, you then remove the mylar strip after the hole is completed.
You could also use a step drill bit to block deep penetration, and you should also use a center punch mark to guide your drill bit.
There is no room for error when doing this drilling. I hope to get pics up for you soon.

 

Can you post some pictures on the problem is? I don't really understand what you mean? Thx.

 

Pictures are now posted on page 2.

 

Photos of DEVOURS car..

 

Many many thanks to 'gsp1' for helping me with these pictures.
The cavity wax we previously talked about is visible around the holes.
All inner spaces are coated with cavity wax but not blocking the flow of water exiting the holes.

 

OMG.. I better check if my B has these or not. Is there any way to prevent/fix it?

 

Thanks for the useful information DEVOURS & GSP1 those pictures really save a thousand words.

 

Ok this seems too serious.. BUT i think i am not willing to drill my bonnet !!!

I'll ask also my local dealer to see what they will say... what about the corrosion guarantee? i think mercedes gives 30 years? (!) or not?

 

Read the script, drill the holes,it's as simple as that.
In Canada we have a 5 year rust out warranty, not like the rest of the real world which has 30 years.
It hurts to drive a beautiful little car in such harsh winter weather, but such is life. I plan to beat this problem before it starts.
Rust is like an aggressive cancer, it's very hard to stop once it's started. Check out similar postings at the bottom of this page.(ie:SA Won't Address)

 

So has anyone out there noticed if the newer B class has better drainage in the bonnet than my B from Dec. 2005.

 

On the bonnet on my June/July 2007 built B they have added additional drainage Vents/holes

Have only recently noticed this with help from DEVOURS photos (thanks)


Keith

 

The beige cavity wax( which I sprayed in) can be seen in the above pic.

I've also sealed off both of those holes.

 

DEVOURS have you actually had any rusting yet or is this a preventative measure. I thought I read somewhere (there's so much info floating about it's a bit difficult to remember where) that the Bs bodywork is galvanised. Ok it will rust if the galvanising (if done ) gets damaged and your conditions are much harsher than ours.

 

DEVOURS,

To be honest, your pictures surprised me. While my car is a year newer, it has been driven through a winter, and the car sits outside 100% of the time and other than some minor dust and dirt (touch wood) there is absolutely no rust (surface or otherwise) anywhere on the car (suspension included). I'm wondering if Quebec uses a much harsher salt mixture than the Toronto area?

Jeff

 

That stuff on DEVOURS car that looks like rust stains is actually the anti-rust compound.....I asked that question too

Having written that, there is a report on the German B Class forum that the door bottoms on some cars are rusting....?

 

Here is the photo/link

The shot is of the tailgate, dark blue car..... What a mess! The speculation is that it only affected a small batch of Bs.

www.b-klasse-club.de • Thema anzeigen - Rost an Tueren und Klappen

 

Doesn't look like they are galvanised then or if so they are left exposed to the elements before treatment.

 

We have to nail that galvanizing answer about our B class once and for all!
Mike found out that all classes are galvanized now.

How come that isn't a selling point when we were at the dealer.

There is absolutely no rust on my B.
The cavity wax has been applied on most metal to metal contacts of my B. All doors, all hinges, all seams...
The salt applied in Quebec is scary, from now to April. Last night the temp dropped below freezing up north where I live. The preceding day it rained all day. They have no choice but to salt.

"I promise you all that all our bonnets will rust out in the future."

If the galvanizing is there, it will make a big difference by slowing the process down.
Remember that the galvanizing is simply the sacrificial metal compared to the steel under.
If you plan to keep your B for a very long time, then do something. Looking at my B from the outside, you can't see any cavity wax and I'm not worried about the looks underneath.
The last thing you want to see is a water trap. That bonnet has water traps!

Rust is like cancer, once started, it's very hard to stop!

 

That is one scary pic. with all that rust.
I can't imagine a galvanized panel failing that fast. But in Quebec all older vehicles look like that if you haven't made any "extra" efforts to stop it. That wonderful large caulking around many of our seams will actually make the rusting process worse. If the moisture creeps between the seams(and it will), then that caulking will trap more water in the seams and help keep it there and then the rust process starts. But it does take time.

Cavity wax is by far," not" the best defense against rust. The best availably defense is yearly oil or grease undercoating. But what a mess.
The rest of the world has glass shops for vehicles and here in Montreal we have underspray shops on many corners.
The logic is that if you keep the seams full of oil and grease, then the water can't get in and start the rust process and it works.

The MB dealers won't allow any outside products applied without voiding the body warranty. So I feel safe applying more of what's already there.

 

Yes a truly horrific picture

The B came out in (UK) September 2005 probably a bit earlier in Germany. I would like to know how a panel came to get like that in around 2 years.
Years ago we had some grottily protected cars (I'e had a lot of experience with the early BMC Austin / Morris Minis) and even with them it would take something in the order of at least 4 years to get in that sort of state & were talking 40 years ago here when rustproofing was just a coating of underseal on the underfloor of the car.

One would hope he got that fixed on his warranty or would they wriggle out by saying the rust had come from the inside out and was not covered ?

The strange thing is that photo looks( as far as I can determine) like part of
the rear (boot) door but being so obvious wouldn't you have thought that the owner would have got something done about it before it got to that state ?