Corvette Central Mufflers Leaking at Seam - NCRS Discussion Boards

Corvette Central Mufflers Leaking at Seam

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  • Mark E.
    Extremely Frequent Poster
    • March 31, 1993
    • 4497

    Corvette Central Mufflers Leaking at Seam

    The Corvette Central mufflers on my 1970 are leaking around the seam between the muffler's end piece and outlet pipe. The photo shows discoloration from the leaks.

    Should these seams be welded? Or is there another cause?


    1970 Muffler Joint.jpg
    Attached Files
    Mark Edmondson
    Dallas, Texas
    Texas Chapter

    1970 Coupe, Donnybrooke Green, Light Saddle LS5 M20 A31 C60 G81 N37 N40 UA6 U79
    1993 Coupe, 40th Anniversary, 6-speed, PEG 1, FX3, CD, Bronze Top
  • James W.
    Extremely Frequent Poster
    • November 30, 1990
    • 2640

    #2
    Re: Corvette Central Mufflers Leaking at Seam

    I'd send them these pictures and demand a new pair.

    The N11 exhaust system I bought from them for my '65 about a year ago is badly dented on the intermediate pipes and one of the mufflers. Not happy at all, but I don't know what recourse I have. The car will be flight judged and I'm looking for every point I can get.

    James

    Comment

    • Russ S.
      Extremely Frequent Poster
      • April 30, 1982
      • 2160

      #3
      Re: Corvette Central Mufflers Leaking at Seam

      I would say that minor leak is normal.

      Comment

      • Bob I.
        Very Frequent User
        • November 8, 2006
        • 265

        #4
        Re: Corvette Central Mufflers Leaking at Seam

        The Gardner exhaust I have on my 1970 leaks in the same location. Only the right side leaks so far.

        Comment

        • Patrick H.
          Beyond Control Poster
          • November 30, 1989
          • 11602

          #5
          Re: Corvette Central Mufflers Leaking at Seam

          If you apply blackout, you don't see this issue.
          Vice-Chairman (West), Michigan Chapter NCRS
          71 "deer modified" coupe
          72 5-Star Bowtie / Duntov coupe. https://www.flickr.com/photos/124695...57649252735124
          2008 coupe
          Available stickers: Engine suffix code, exhaust tips & mufflers, shocks, AIR diverter valve broadcast code.

          Comment

          • Mark E.
            Extremely Frequent Poster
            • March 31, 1993
            • 4497

            #6
            Re: Corvette Central Mufflers Leaking at Seam

            Is this seam typically welded? If so, this may be the easiest fix.
            Mark Edmondson
            Dallas, Texas
            Texas Chapter

            1970 Coupe, Donnybrooke Green, Light Saddle LS5 M20 A31 C60 G81 N37 N40 UA6 U79
            1993 Coupe, 40th Anniversary, 6-speed, PEG 1, FX3, CD, Bronze Top

            Comment

            • John S.
              Very Frequent User
              • June 15, 2015
              • 505

              #7
              Re: Corvette Central Mufflers Leaking at Seam

              Mark, not exactly an apples to apples comparison but here’s a shot of the CC system on my ‘73. The configuration of the muffler is certainly different but I do not have any welds in that location and no leaks noted. The system has been installed for 8+ years and approx 8000 miles.

              I’d call CC to get their input but I would probably have it welded if they aren’t willing to help you out. Good luck !!

              0E258850-5582-410F-AB29-E88CD070E41D.jpg
              1973 L82 M21 4 Speed, very original and well documented driver/survivor
              NW Chapter Member, 2016 Bend Regional Top Flight
              73/74 TIM&JG 3rd Edition Revision Team Member

              Comment

              • Gary B.
                Extremely Frequent Poster
                • January 31, 1997
                • 6973

                #8
                Re: Corvette Central Mufflers Leaking at Seam

                Mark,

                This is what that junction looks like on my new Gardner system. There is no external seal between the exit pipe and the muffler end plate.

                Gary

                IMG_7616.jpg

                Comment

                • Mark E.
                  Extremely Frequent Poster
                  • March 31, 1993
                  • 4497

                  #9
                  Re: Corvette Central Mufflers Leaking at Seam

                  Thanks folks. I'll keep you posted with what CC says.

                  Happy New Year!
                  Mark Edmondson
                  Dallas, Texas
                  Texas Chapter

                  1970 Coupe, Donnybrooke Green, Light Saddle LS5 M20 A31 C60 G81 N37 N40 UA6 U79
                  1993 Coupe, 40th Anniversary, 6-speed, PEG 1, FX3, CD, Bronze Top

                  Comment

                  • Mark E.
                    Extremely Frequent Poster
                    • March 31, 1993
                    • 4497

                    #10
                    Re: Corvette Central Mufflers Leaking at Seam

                    Update-

                    After telling CC their mufflers leak and are significantly louder than stock (not due to the small leak), they shipped me a replacement pair which arrived yesterday. They said I'm the first customer to complain about these two issues (leaks and noise level), and can't promise their new mufflers are quieter. But their current muffler supplier is different than what I have now and may or may not sound different (they purchase mufflers and weld on the unique Corvette bracket and end pipes).

                    So they asked me to video the noise level before and after the muffler swap, and post it to their blog. I'll also share this here.

                    The photo below of the new muffler shows the weld bead around the outlet pipe at the case, unlike my existing mufflers. Also note the outlet pipe is now a single piece welded to the case, unlike the existing CC mufflers which have two pipe segments butt welded (not shown but same for the inlet pipe). Looking at Gary's and John's photos in their posts, their replacement pipes are not welded to the case and are two pieces, same as my existing CC mufflers. CC says this is now standard for their mufflers, but wouldn't say why they made this change (leaks?).

                    Question for all of you: How does this outlet pipe compare to original?

                    20240124_160457.jpg
                    Last edited by Mark E.; January 24, 2024, 05:40 PM.
                    Mark Edmondson
                    Dallas, Texas
                    Texas Chapter

                    1970 Coupe, Donnybrooke Green, Light Saddle LS5 M20 A31 C60 G81 N37 N40 UA6 U79
                    1993 Coupe, 40th Anniversary, 6-speed, PEG 1, FX3, CD, Bronze Top

                    Comment

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