I have some minor rust in the wheel well of my 98 E320. It looks like there might have been some damage from a rock strike or something a while back that and the previous owner didn't get repaired and rust formed. It's starting to spread to the outside of the car and become visible so I want to stop it before it gets any worse.

I have been reading up on rust inhibitors such as Rust Bullet and POR-15. My basic plan is to treat the surface and repaint with touch-up paint. The majority of the rust damage is inside the wheel well and pretty much invisible so I don't too much about the quality of the finish. But I want to be very careful with the two bubbles that are visible from the outside to get it as nice looking as I can. I know it won't be perfect, but as long as it's not very noticeable I can live with it.

Anybody been down this road before that might be able to offer some tips?

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Vienna, Virginia
1998 E320

Peter,

You are definitely doing the correct thing by arresting the progress of the rust. I also think that you are on the right track of repairing it. If you can neutralize the rust that is already there, the location of what is visible is not that evident to a casual observer. You have to be very careful to remove the bubble that has formed on the outer lip of the quarter panel by sanding or grinding the bubbled paint down to the metal, put some POR15 or such on the repaired section and carefully brush some paint into the repair. It should last a long, long time. Maybe by then you will need a complete paintjob. I say go for it.

Tom

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1993 300TE
1984 300D
1984 300SD
1976 BMW R90S

Thanks for your input. Yeah, I figure if I screw it up bad I can always get the panel repainted. Which is what I would need to do anyway eventually if I let the rust get much worse...

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Vienna, Virginia
1998 E320

This will be a bigger job than you think. Your plan is sound but rust and painting always are a bigger job then what it seems like on the surface.
I used POR-15 extensively on my Sons 65 Mustang. It is good stuff AS LONG AS YOU FOLLOW THE DIRECTIONS. Use all 3 of their products and don't' cut any corners. POR-15 cleans up with their cleaner or 3M weather strip adhesive remover will also do the job.
POR-15 works best on a rough surface. It gives it something to grab onto. If you sand or grind the rust down to new bare metal, it may separate from the metal.
Clean the wheel well completely of dirt and grease. A wire wheel on a drill is good, along with a strong degrease, rinse completely. Then use the Marine Clean to completely degrease the wheel well. Apply Metal Ready. Do not let it get on any painted surface you do not want to discolor. Then apply the POR-15 paint. Cover yourself completely, gloves, long sleeve shirt, etc. POR15 is a polyurethane paint and if it dries on your skin you will have to wear it off, about 1.5 weeks to completely disappear.

The bubbles. More than likely they will grow in size as you start to remove the rust. Expect this. The POR will work fine but once you touch up the area it will be noticeable. Painted, but not perfect. Now the bubbles may be rusting thru from the wheel well, this is common. Don't freak out if it has done this. POR15 has a 2 part putty that may be used to fill. You can then sand it smooth. They also have a gel type POR 15 paint.

So if you want to preserve the fender, POR15 it. but as I said when it comes to rust, there will be more than is showing once you get into the job.
Also, if that fender is rusted your other fenders may have started on the rust path. Take a look

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

I have similar rust problems.... but I dont see myself getting into fixing till late summer...in the interim are there any stop gap stop rust procedures....anything i can spray or apply to halt the decay... or stop it from spreading....im attaching a few small pics.... will send out the big ones when I undertake the project...

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***SAMI*****
1986 300E 240K
1999 Mitsubishi Spyder GS 60K

scrape the scaley rust.....sand it and use a rust converter or even rustoleom rusty metal primer....it will slow it down.....treat rust as you would cancer...doing nothing is the worst thing you can do..........even if it gets handled right in the summer do what you can now to slow or stop it.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Dave, thanks for the tips, you're probably right that this will be a bigger job than I think (it usually ends up that way ) However, I think this rust was caused by hidden body damage, not by general rusting conditions, although I have heard that the W210s often have rust problems. The rusty metal in the wheel well appears a bit misshapen in places, making me think that a rock or something must have kicked up from the wheel, doing damage that went unnoticed for several years. I inspected all the other wheel wells and they are rust free and in perfect condition. My hope (wish?) is that this is an isolated event, not an indication of things to come. I guess I'll find out eventually, one way or the other.

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Vienna, Virginia
1998 E320

If you look in the wheel well you can see some overspray...

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#dieselFLEET
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'97 E300
'99 E300

Although I can not compare with Por15, I have used Rust Bullet and I am really pleased with how it goes on. I have treated my W210 under the door seal rust.

I would talk to the dealer you might get some good will. They have been fixing rusty W210's.

As for the W124 find a good set of rust free doors. I have seen a few MB's with rust in their it starts under the plastic you are only seeing a small part of it. I bet their are holes in the doors.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I'm from the old school where any rust repair first starts with COMPLETE removal of the rust. Garden-variety rust is chemically a hydrated iron oxide. This oxide is porous and traps moisture which can cause further corrosion if left underneath a paint layer.

For large-scale rusting I use a sand blaster. For tiny spots I use a dremel tool. Tough my repairs aren't perfect, the rust is stopped dead! I'd rather see a few small scars with touchup paint than have a repair job show up later as a bigger spot that needs to be re-repaired.

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95 E320 Cabriolet, 159K

I have rust on the lower front fenders (both sides) just below and to the side of the headlights.

I was going to havee a body shop fix this, but my MB mechanic suggested getting new fenders instead. I have seen them on this forum and on eBay relatively cheap.

Is this the way to go?

-gil

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GG NJ USA
1983 300SD (Sold at 198K)
1989 560SEL (205k) - slowly restoring
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1995 Colt Vista AWD (145k) - fun car! spare
1991 Buick Riviera 3.8l (85k) - fur die Kinder
RIP: 1965 LeMans/GTO Convertable -my first
RIP: 1968 GTO 400 HO w/ 400HP - ballsy!
(blew the motor racing a '69 GTX - bummer)

It's a personal decision, but I would only consider it if there is perforation of the sheet metal. If there is no perforation, just repair the original fender.

Who makes the replacement fender? I've seen replacement parts from Asia that just aren't as good as the original... they don't have the definition and structural detail of the original part. Then you always have to consider the fit... will the replacement fit as well as the original? I'd hate to see you fix one problem (rust), then have to deal with another problem (fit) that is just as ugly. Make sure you can trust the replacement part.

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95 E320 Cabriolet, 159K

From what I have noticed on my car the rust seems to form holes making any repair a fiberglass bondo job.

I need at least 1 if not both fenders when I do my body, this is what I have found:
OE fenders list for $399 but I could probably get them from my dealer for $350.
Aftermarket fenders are just under $200 but from what I have been told are junk. I am not considering them for my car.
Junkyard fenders. You will have to look hard to find a perfect rust free set and probably pay shipping from down south.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Agree that aftermarket fenders are junk.

Also that junkyard is no good.

But when someone blows an engine in an otherwise good shape 126, they part out the car and then fenders can be had relatively cheaply.

-g