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Rust - weld in new plate or grind out rust?

Discussion in 'Bodywork, Tyres, Wheels & Trim' started by Paul SL320, Sep 24, 2018.

  1. Paul SL320

    Paul SL320 Member

    Likes Received:
    May 11, 2011
    NE England
    Your Mercedes:
    I'ts your advice and experience I need on rust around the edge of the rear quarter panel where it meets the rear bumper at the wheel arch.

    The rust does not seem to be right through the edge. So it seems I can either have the steel ground until its back to bare steel. Or have the edge cut out and a new repair piece welded in place. Then primed and sprayed in either case.

    On the one hand all of the rust may not ground out. On the other hand I don't know if welding will cause the steels properties to be altered leading to rust.

    What in your experience is most likely to give the longest lasting repair?

  2. daveenty

    daveenty Senior Member

    Likes Received:
    Jun 21, 2005
    The Frozen North :(
    Your Mercedes:
    2017 W213 E63s & 1989 W201 2.5-16
    I've replied elsewhere but to reiterate. If you can grind it all out then all well and good.

    If you can't get to all of it (and I do mean all) then cut it out and weld a piece in. A competent welder will carry out all the necessary protection including sealing the rear of the panel so no rust returns.
  3. charlysays

    charlysays Senior Member

    Likes Received:
    Jan 11, 2016
    Your Mercedes:
    Mercedes C250 Turbodiesel Sport Auto Estate
    Whilst this used to be the only way with thick surface rust, it's not anymore.

    Bilt Hamber make a rust removing Gel called Deox Gel. You tickle the worst off and clear back to sound paintwork all around the rust with a flapper disc then spread the deox gel on and put cling film over it. Leave overnight. Next day wire brush it then wash with water. It may take a few applications for really deep seated surface rust but this stuff will remove all of the oxide even from the bottom of deep craters leaving fresh clean steel. It's quite interesting to see the craters once all the oxide is gone, with clean steel in the bottom of them. It was developed for this exact situation common to Mercs- sound metal with surface rust.

    6 years ago I used it and their electrox primer on my W202 wings which had gone into pinholes in places. 6 years later still no sign of rust!
    daibevan and alexanderfoti like this.

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