How loud are exhaust leaks?

Discussion in 'Mechanics Garage' started by woody77, Oct 19, 2015.

  1. woody77

    woody77 New Member

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    How much should I care about exhaust leaks? I repacked the supertrapps last weekend (they were in better shape than I thought, but now they're full of stainless steel wool and fiberglass). And while I didn't check for leaks _before_ doing the work, I did check for leaks afterward (mostly because pounding the cores off the mid-pipes was an awful experience that really banged things up).

    So, I have leaks I can feel with my bare hand at both muffler inlets, and one side at the header to mid-pipe joint.

    I can crank the clamps down tighter, but I'm not expecting that to fix the leak, I'm guessing it's from the damage from separating the press-fit components of the mufflers (since these are probably 30yo assemblies).

    I _might_ be able to seal them by loosening the clamps, squeezing in copper rtv, and then clamping back down and letting it cure.

    But, how audible are leaks like this?

    How much of a performance impact, if any, do they have?

    It's a dual exhaust, 8-spacer, supertrapp setup. Quiet it isn't, and free-flowing it is. But there's clearly enough pressure inside the pipe (vs. the outlet), that it's able to puff out such that my hand can feel it when next to the pipe.

    (86 VFR700)
     
  2. woody77

    woody77 New Member

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    finally got out and rode today, and they're definitely audible.

    pfft-pfft-pfft-pfft at idle, much quieter than the exhaust note itself, but still quite present. It mostly goes away as road speed picks up (or rather is drowned under the wind noise).

    So I'll be trying to figure out how to seal these up. The header to mid-pipe actually has a gasket that I might be able to replace (I don't think it's the stock seal types). But the press-fit joints at the mid-pipe to canister/core are going to be harder to deal with.
     
  3. squirrelman

    squirrelman Member

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    Maybe try cutting a thin, long strip from a beer can (must be beer!!) and using that as a gasket to seal the leaky gaps ??
     
  4. TOE CUTTER

    TOE CUTTER Mullet Man

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    I believe the 0EM gaskets are available and with a quality constant tension set of clamps you can cut a small slit in the portion of the pipe that holds the gasket and tighten it down. I have done this repair many times and it works well. If you go on the hunt you can find nice wide clamps that look nice and when positioned correctly can't be seen. I hate to say it but the place I know where to get nice clamps is a Hardley shop.
     
  5. woody77

    woody77 New Member

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    Hey Toe, do the supertrapp mid-pipes use the OEM gaskets at the mid-pipe to header joints? Also, how do YOU usually separate the can/core from the mid-pipe? I ended up using a large screw-driver as a flat punch and drifting the core off the mid-pipe with a hammer. Took about an hour per side, and made a big f*****ing mess of the pipes in the process (especially since I have no patience for such things).


    I have stainless t-bolt clamps (but not constant-tension ones, which I probably should have gone with), and today I picked up some ultra-copper RTV. Hopefully I can dig into it tomorrow and seal up the can/core/mid-pipe joints (those are making the most noise, as far as I can tell so far). But I'm not going to take the cans back off the mid-pipes again, that's 2 hours of my life that I'd like back (and don't plan on spending again).

    I really think I should have picked up a pipe expander and loosened up the fit of those before re-assembly. Just to the point where they'd hand-assemble, and then seal tight with the clamps.

    The mid-pipe to header joints are pretty easy to deal with but those use gaskets, unlike the mid-pipe to can.
     
  6. woody77

    woody77 New Member

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    However, as much of a PITA it was, the new packing does sound different. The stainless wool+fiberglass gives it a mellower sound, more boomy, less raspy. At least, I think it does (it could all be in my head). If I can seal up the leaks, it should sound pretty awesome (louder than I want, but awesome nonetheless).
     
  7. NormK

    NormK New Member

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    Try bathroom silicone sealant, it is the only way to seal up the header pipe on an Enfield into the head. Believe it or not it will take the heat
     
  8. woody77

    woody77 New Member

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    Ultra Copper RTV seems to have done the trick.

    I loosed and backed-off all the clamps, and laid a bead down into the can/core/midpipe joint (at the end of the can, since I wasn't about to disassemble). Basically treated it like caulking up a joint. Then set the clamps in place, but left them mostly loose. An hour or two later, after it had set up, I cranked the clamps down nice and tight.

    For the mid-pipe to headers, I just removed the whole muffer/mid-pipe assemblies, coated the inside of the midpipes with rtv, and then re-assembled. And after the 1-2 hour wait, tightened up the clamps all the way.

    A quick start shows no leaks. I can't go for a ride until tomorrow at the earliest, and I probably won't get out until later in the week, but I'm expecting this to hold pretty well.
     
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