Permatex sealant melting

Discussion in 'The Garage' started by narwaffles, Jun 9, 2020.

  1. narwaffles

    narwaffles n00b

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    I put an fmf q4 on my wr250r and on the directions it said to use high temp silicone to seal it where it meets the header. I have tried every permatex color, called fmf multiple times, and tried other exhaust sealant options made for cars but nothing has worked. I apply the permatex and wait 24 hours or more but it just turns into goo the first ride after applying it. The people at fmf keep just telling me to try (x) color and I have been but now that I've tried every color permatex they told me to use Honda bond. I am going to try the Honda bond as soon as it arrives in the mail but I am sure that it will not work since none of the permatex would and the honda bond is only good for a much lower tempurature. I have no idea why it's not working for me or what to do. Does anyone have any advice please? Thank you for any help.
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  2. BluByU

    BluByU Long timer

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    Not sure if this will help but, I have used the copper colored permatex stuff on exhaust connections in the past and it worked for me. If memory serves me right (ya I know) it's is good for 1500'f
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  3. narwaffles

    narwaffles n00b

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    Thanks but yeah I tried it too. It just turned into goo just like the rest of them. I have no idea why since it seems like it works for everyone else. I can't imagine that mine would be getting a whole lot hotter than anyone else's bike but it's just not working.
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  4. tire joe

    tire joe Been here awhile

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    Ultra copper works for me.
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  5. gmiguy

    gmiguy You rode a what to where?

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    What happens after it comes up to temp?

    Does it run off the joint? Blow out? Leak exhaust? Hold the exhaust in but get soft to the touch?

    Understanding the specific failure mode will help with figuring out what is happening and how to resolve it.
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  6. gonerydin

    gonerydin Been here awhile

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  7. narwaffles

    narwaffles n00b

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    The little bit on the outside just turns into goo and eventually falls off completely. The stuff on the inside between the two pipes where they slip together turns to goo too but it stays put until I take it apart and wipe it or it burns off completely after a few rides, but it is useless being there because it isn't solid anymore and doesn't prevent the exhaust from escaping because if i put soap over it and partially block the end of the exhaust (where it is supposed to come out) than the soap makes bubbles. I hope that makes sense.
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  8. narwaffles

    narwaffles n00b

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  9. gonerydin

    gonerydin Been here awhile

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    I’ve never used it. And you probably can’t buy less than a gallon. You’re unlikely to find a silicone RTV that is good for over 700F. In the few times I have needed to seal an exhaust header I have gotten by with Dow Corning 736 which is only good for 600F. It would be interesting to know just what temps you are seeing.
    #9
  10. Yamarocket630

    Yamarocket630 Honey Badger

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    Is the leak enough to cause a problem? Unless there is a large gap between the pipes, any leak should be very small and will eventually seal itself with carbon.

    If that's the case, attempting to seal it is just being pedantic.
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  11. katbeanz

    katbeanz earthbound misfit, I Supporter

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    If it's not burning your leg or bodywork, not sure I'd be too concerned. My xrl's stock exhaust has a thin graphite looking sleeve between the header and muffler with a beefy clamp over top. That stuff is brittle enough it won't bend too far without breaking. Might measure ID and OD to see how much room you have to work with. Maybe a layer of header wrap, angled cut and a clamp? I have a scrap of thin heat resistant conveyor belt, all they sent to splice those (~6"overlap) was clear silicone. My BigGun headers x2 have just a taper slip fit. The soapy water test is normally for piping that sees much higher pressure than engine exhaust. :dunno
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  12. kantuckid

    kantuckid Long timer

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    I have watched pro installers at MC rallies who all seemed to use high temp copper to assemble aftermarket exhaust systems. I know that might not make your's OK but that's the norm I think. If it leaks that easily, maybe it's a bad design, whatever?
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  13. JohnE65c

    JohnE65c Been here awhile

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    Is there a snug slip fit between the i.d. of the Q4 and the o.d. of the header? If there is any kind of measurable gap that has to be sealed off, it would seem that all the header heat is trying to dissipate through the sealant alone and melting it.
    #13
  14. Beezer

    Beezer Long timer Supporter

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    Honda Bond is a case sealant, it makes tight clearances oil tight... that has no chance at all. if the gap is too big most sealants will struggle. I would get some HVAC metal foil tape (try Lowes) and give the pipe a wrap or two until its snug. then wipe everything down with rubbing alcohol and slide it together with the copper RTV. let the RTV sit in the open a few minutes before assembly, it needs humidity to cure and the alcohol help

    Locktite red works well too. some other brands do not seem to fully cure
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  15. BluByU

    BluByU Long timer

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  16. gonerydin

    gonerydin Been here awhile

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    I with you. I don’t rely on my memory for much anymore.
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  17. lkraus

    lkraus Long timer

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    When you block the end, you are creating greater than normal pressure inside. If you only get bubbles, and are not totally blowing the soap out immediately, it really is not much of a leak. If the soap does not bubble without the blockage, it is not leaking.
    #17
  18. EkisGrios

    EkisGrios n00b

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    I never had such an issue, but I can definitely say that it is a complex procedure. I guess you should’ve applied it better. I had an issue a while ago, and I had to use silicone sealant to solve it, and the only problem I had is that I had no idea how to apply it. I went on the internet to find information about it, and after hours of searching, I was able to find a website sealwithease.com that had an article about silicone sealants and how to apply it. It helped me out, and I was able to fix my issue. Maybe you will be able to find any helpful information there. That is why I would love to recommend it to everyone.
    #18
  19. vtduc

    vtduc Been here awhile

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  20. fritzthecat

    fritzthecat Been here awhile

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