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Premium Member
1988 560SL, TRQ
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218 Posts
Discussion Starter · #1 ·
Found a body rust area that needs attention. Long term would be to have a reputable body shop address it. In the short-term what is the recommendation to treat it. Thanks for you help.
2690563
 

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'79 450SL, '04 CLK200 convertible; former A124, W210, A209.
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3,134 Posts
I'd recommend you remove the chrome strip which will give you a better idea of the rust, and short term Eastwood or POR15 will work. Long term the fender needs to go and you're looking at welding the rotted areas. You may want to check the other side as well as chances are high it suffers from similar challenges.
 

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Premium Member
1988 560SL, TRQ
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218 Posts
Discussion Starter · #5 ·
I'd recommend you remove the chrome strip which will give you a better idea of the rust, and short term Eastwood or POR15 will work. Long term the fender needs to go and you're looking at welding the rotted areas. You may want to check the other side as well as chances are high it suffers from similar challenges.
Thanks.
 

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1977 450 SEL 6.9
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847 Posts
Be prepared for the rust to be a lot worse than what you can see in this pic. It looks like the cancer spread to the jack hole, so likely the rocker panel will be crispy as well:(
 

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Premium Member
1988 560SL, TRQ
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218 Posts
Discussion Starter · #7 ·
Be prepared for the rust to be a lot worse than what you can see in this pic. It looks like the cancer spread to the jack hole, so likely the rocker panel will be crispy as well:(
Yep, I will do a thorough inspection of it.
 

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1987 560SL
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90 Posts
Unfortunately what you see on the surface is just the tip of the iceberg, it will be far worse and further spread underneath the paint. Ideally you need to grind the paint and rust off and liberally treat both sides of the metal with a rust converter until you can get a body shop to deal with it properly. No doubt the fender will need to come off. You really need to check out the jacking tube below that area and the drainage channel below the leading edge of the door.

There is an excellent video on YouTube by Mike’s Mercs
that details how the rocker and the drainage channels are comprised and how rust can be a real problem in this area if not protected.
 

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Premium Member
1988 560SL, TRQ
Joined
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218 Posts
Discussion Starter · #9 ·
Unfortunately what you see on the surface is just the tip of the iceberg, it will be far worse and further spread underneath the paint. Ideally you need to grind the paint and rust off and liberally treat both sides of the metal with a rust converter until you can get a body shop to deal with it properly. No doubt the fender will need to come off. You really need to check out the jacking tube below that area and the drainage channel below the leading edge of the door.

There is an excellent video on YouTube by Mike’s Mercs
that details how the rocker and the drainage channels are comprised and how rust can be a real problem in this area if not protected.
Excellent video. Thank you.
 

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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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12,093 Posts
I agree with 560SLUK. Here in Canada, we often have rust like that. My SL has no visible rust but our 300D and E320 see road salt and this type of a job is needed annually. If caught early, the rust doesn't necessarily spread. Just have to keep on top of it.

  • For a start first tape off that area - maybe along the top of the first flute.
  • Using some coarse (80grit?) sandpaper, remove the paint and surface rust in the rusted area and an inch or two each side. Hopefull there are no perforations. If there are small ones, there are fillers that can be used.
  • See if you can remove the trim below. There might be rust under that that needs similar treatment.
  • wire brush with small brush and sand the rusted area to remove any loose surface rust.
  • Apply a coat of rust converter - This will convert the surface rust to an inert substance that can be overpainted.
  • Try to find a small sample size can of POR-15 or a similar rust ecapsulator. (Problem is that these paints are quite expensive and have very short life once opened.) (this kit might be suitable. The metal prep is a rust converter)
  • Try to apply the POR15 in thin smooth coat. It dries very hard and is not easy to sand. Usually best not used on exterior bodywork, for this reason. But should work here.
  • Finally, mask large area around repair and spray on several thin coats of primer and matching finish paint. You may have to sand the primer in-between coats to get a smooth finish.

Try scraping and cleaning the paint around the jack point. You could use the POR products there too and overpaint with any black paint.

THis link has some useful articles on rust treatment, in general.

Good Luck.
 

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1984 300D
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5,488 Posts
I'd recommend you remove the chrome strip which will give you a better idea of the rust, and short term Eastwood or POR15 will work. Long term the fender needs to go and you're looking at welding the rotted areas. You may want to check the other side as well as chances are high it suffers from similar challenges.
Yes there is usually more extensive rust then you think and when you have removed the rust you are going to find metal is simply gone and needs to be filled in with something.

I am guessing youtube will have some rust repair videos.
 

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1984 300D
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5,488 Posts
On W123's there was formed metal parts you could buy to replace rusted out areas. Never looked into that to know what years and models are covered.
 

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18 Posts
Dude,

if its like that now, its canercous underneath. You need to pull the panel (replacement sections are available) and repair it. Rust treatments won't do much unless you get in there.
 
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