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M20 Downpipe Flex Joint Repair?

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    M20 Downpipe Flex Joint Repair?

    I have a 1990 325ix that has developed a leak at the downpipe flex joint. The leak is actually on the bottom of the flex joint where it welds to the pipe. The cat has been removed from this car by a prior owner.

    A mechanic attempted to repair the pipe, but the repair did not last. When I took it back to him to look at, he stated the pipe (not the flex joint) was too thin to weld and that I would just have to get new downpipes.

    Sooooo..... is he right? Or, is there some sort of repair I can do to replace the flex joint that will actually weld to the pipe? I'm open to suggestions!
    1991 325ix Coupe 5 Speed
    1990 325ix Sedan Auto
    2001 M3 Convertible 6 Speed
    +2002 M3 Convertible SMG (RIP)
    1972 Ford Bronco

    Instagram: @steine20

    #2
    He probably said that the flex joint material is too thin to plausibly weld. The pipe itself is perfectly weldable.

    Just get a new flex joint and have it welded to the pipe.
    2006 GMC Sierra 2500HD 4WD LBZ/Allison
    2002 BMW M3 Alpinweiß/Black
    1999 323i GTS2 Alpinweiß
    1995 M3 Dakargelb/Black
    - S50B32/S6S420G/3.91
    1990 325is Brilliantrot/Tan
    1989 M3 Alpinweiß/Black

    Hers: 1996 Porsche 911 Turbo Black/Black
    Hers: 1988 325iX Coupe Diamantschwartz/Black 5spd

    sigpic

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      #3
      Originally posted by nrubenstein View Post
      He probably said that the flex joint material is too thin to plausibly weld. The pipe itself is perfectly weldable.

      Just get a new flex joint and have it welded to the pipe.
      I thought the same thing, so I asked him about just replacing the flex joint. He was very specific - and I made sure to ask - that the pipe was too thin to weld, not the flex joint. Frankly, it didn't make sense to me either.
      1991 325ix Coupe 5 Speed
      1990 325ix Sedan Auto
      2001 M3 Convertible 6 Speed
      +2002 M3 Convertible SMG (RIP)
      1972 Ford Bronco

      Instagram: @steine20

      Comment


        #4
        Originally posted by Steiner View Post
        I thought the same thing, so I asked him about just replacing the flex joint. He was very specific - and I made sure to ask - that the pipe was too thin to weld, not the flex joint. Frankly, it didn't make sense to me either.
        He may just not have access to acceptable welding equipment / skill.

        (Although what that lack of skill may be, I don’t know. Novice welder me could do it, and an M20 midpipe was one of the first things I ever welded.)
        2006 GMC Sierra 2500HD 4WD LBZ/Allison
        2002 BMW M3 Alpinweiß/Black
        1999 323i GTS2 Alpinweiß
        1995 M3 Dakargelb/Black
        - S50B32/S6S420G/3.91
        1990 325is Brilliantrot/Tan
        1989 M3 Alpinweiß/Black

        Hers: 1996 Porsche 911 Turbo Black/Black
        Hers: 1988 325iX Coupe Diamantschwartz/Black 5spd

        sigpic

        Comment


          #5
          Don't rule out the possibility that being in MI the pipe could be corroded to the point of being too thin to weld
          Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

          https://www.r3vlimited.com/board/sho...86#post4944786
          Alice the Time Capsule
          http://www.r3vlimited.com/board/showthread.php?t=360504
          87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

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            #6
            Hi, I too just picked up an e30 with a leak in the exact same spot and wondering if you ever got it fixed and how? Thanks

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              #7
              Originally posted by mike11339 View Post
              Hi, I too just picked up an e30 with a leak in the exact same spot and wondering if you ever got it fixed and how? Thanks
              Wanted to chime in here as well. My midpipe was rusted to the point of no repair and developed a bad leak at the flex joint. Shop told me that the midpipe needed to be replaced. Unfortunately, they don’t manufacture OEM midpipes for the M20 anymore so you have to gamble with aftermarket ones...
              1986 325e Schwarz (sold)
              1989 325iX Alpineweiß​ (daily)


              Greed is Good

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                #8
                What parts are you guys talking about here? Just take car to proper exhaust shop, get them to fix. end of story?

                Mine was all rusty, they cut it back to where it wasn't rusty and just made new bits and put it all back together.

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                  #9
                  This is the part I’m talking about where the exhaust leak has developed.

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