Header Leak

Discussion in 'Engine Topic' started by mr.cej23, Dec 26, 2016.

  1. mr.cej23

    mr.cej23 Veteran Member

    Aug 10, 2011
    sharpsburg, GA
    So I have a pretty bad exhaust leak where the header mates with the head and I have come to the conclusion that it is a defect in the header. The welded seal on the header around one of the ports is not large enough and therefore does cover the entire opening on the gasket. I hope this makes sense. I'll try to post some photos that will hopefully clarify. You can see the indention of the welded seal on the headers on the gasket. I have already tried multiple types of gaskets, even the metal kind, and I'm pretty sure that no matter the gasket, it is still going to leak. So my question is should I just buy new headers, or is it possible to weld more metal on and then grind it back down, creating a bigger sealing surface? Or is there an alternate solution I have not thought of? If I can avoid buying new headers, I would like to, as I just got a brand new exhaust build from the headers back and I would probably have to get that modified if I got new headers that will probably not have exactly the same dimensions as the current ones. Thanks in advance for any help you have to offer.


  2. Scott Martin

    Scott Martin Veteran Member

    Feb 10, 2014
    Bham Alabama
    The 1404 fel pro gasket you are using has a 1.550 port height and a 1.550 port width if I remember correctly. You may try something like a Mr. Gasket 7153 , it has a 1.550 port height and a 1.450 port width. It might seal off with the narrowed port width.
  3. peteegger

    peteegger Veteran Member

    Jul 27, 2006
    North Las Vegas, NV.
    I agree that your header flange is the problem. I spent hours online and numerous phone calls to try an determine what would work on my ZZ4 raised "D" port heads. In the end it was Doug's headers. Pricey but everything seems to fit. As Scott suggested a narrower width gasket may work but looking at the pictures the clamping area of the headers is minimal around the bolt holes?
    Last edited: Dec 26, 2016
  4. earnhardtgm3

    earnhardtgm3 Veteran Member

    Dec 18, 2007
    Camaro Country,GA
    What brand of headers and heads are you using?
  5. mr.cej23

    mr.cej23 Veteran Member

    Aug 10, 2011
    sharpsburg, GA
    They are hooker headers. I'm not sure about the heads but they seem like standard square port heads. I actually did get new gaskets with the narrower 1.450 port holes and it doesn't seem to help. Is there anything wrong with the idea of welding some additional metal onto the flange and then grindind it back down in order to make a larger sealing surface?
  6. grzewnicki

    grzewnicki Veteran Member Lifetime Gold Member

    Welding it is what I was thinking, then just grind or file it down so it is close in height to the factory weld.
  7. muscl car

    muscl car Veteran Member Lifetime Gold Member

    Have you tried using thick soft metal header gaskets ???
  8. jthomas

    jthomas Veteran Member Lifetime Gold Member

    Dec 5, 2007
    NorthCentral PA
    Are the heads the stock ZZ4 heads (the L98 aluminum heads)? If so, FelPro 1470 are the correct gaskets for those heads assuming a compatible set of headers.
  9. czizza

    czizza Veteran Member

    Jan 8, 2004
    N. Massapequa, NY, USA
    I had a similar looking gasket and changed them recently only to find out a month later that the new gasket also failed as well.

    I have since gotten new headers for Christmas and I am in the process of installing them while doing the install I am also doing a "post mortem/root cause" check as to why has the leak returned.

    I am now sure what has happened my headers are warped and in their current form would never seal properly.

    Here is the 1 month old gasket:

    As you can see I pushed out and up on cylinder 5:

    I put my machinist edge against the flange and you can see light:

    I am not sure if you are in position but if you can check your flanges ... newer headers have thicker flanges so it might not happen with yours.
  10. thrasher

    thrasher Veteran Member

    May 27, 2006
    Not saying this is the OP's problem but some people cut slots in the flanges to give each pipe a chance to pull up and mate to the head as square as it can.

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