New exhaust system won't seal

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Trcknwolf, Nov 30, 2020.

  1. Trcknwolf

    Trcknwolf Bobtail Member

    Nov 24, 2010
    Bellevue, NE
    Hello remembers! Here we go: 1999 Peterbilt 379exhd. Just had a completely new 6" Lincoln Chrome exhaust installed. 114" stacks, 90° Rod Pickett style elbows & the chrome Y-pipe. Everything under the hood & truck mounted up great & sealed aganist leaks as expected. The problem is the stack to elbow joint is leaking. The elbow slides into the stack approx 6 inches, the fit is tight, the clamps are tight. Even used Lincoln Chrome's recommended practice of sealing the joint using Permatex RED RVT High Temp Gasket maker/sealant on said joint. NOPE..... still leaks. I'm just a little frustrated & pissed off!! A $2400 exhaust system SHOULDN'T leak like this, but I nor my mechanic know what else to do.... ANY ideas? Anybody else have an experience like this & what was your solution?? Thanks in advance.
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  3. loudtom

    loudtom Road Train Member

    Aug 26, 2016
    blairandgretchen Thanks this.
  4. 062

    062 Road Train Member

    Oct 20, 2013
    Not a fancy solution, but pull it apart and coat both pipes with grease, then put them together and coat the seam with grease and wrap 2-3 times with aluminum foil and install clamps. The grease will trap soot and the aluminum foil keeps it from being blown out.
  5. 401-Alex

    401-Alex Light Load Member

    Nov 25, 2013
    Advanced auto parts or most automotive parts stores have muffler cement it dries in heat and does quickly

    Attached Files:

  6. SmallPackage

    SmallPackage Road Train Member

    Dec 20, 2019
    Marion Texas
    HVAC aluminum foil tape from lowes wrapped around the joints and under the clamps with ultra copper rtv.
    Or thermo-shield tape from autoparts stores. It is basically the same as the hvac tape but resists exhaust manifold heat better.
    Just trim the tape width so it is hidden.
    650cat425 Thanks this.
  7. jamespmack

    jamespmack Road Train Member

    Mar 25, 2014
    If red high temp, or copper rtv seal it. Something else is wrong. That is the go too. Seen it last 10 years on clamps. Not so much sealing the exhaust. But keeps moisture out. Which makes the clamps and or flex last longer. Then helps seal the exhaust.
  8. spsauerland

    spsauerland Road Train Member

    May 31, 2010
    West Harrison, In
    For $2400, I'd be calling and complaining.
    haycarter, Roberts450 and GreenPete359 Thank this.
  9. haycarter

    haycarter Road Train Member

    Jun 9, 2012
    ^^^^^^^^^What He said^^^^^^^^^^
    Roberts450 and Klleetrucking Thank this.
  10. Trcknwolf

    Trcknwolf Bobtail Member

    Nov 24, 2010
    Bellevue, NE
    I appreciate the ideas. UPDATE: The passenger side stack/elbow joint sealed itself this past week (YAY!!!). Drivers side, NOT SO MUCH. Took truck back to mechanic yesterday. Bought a tube of the Permatex High Temp Copper RVT sealant. They actually got the stack & elbow apart this morning, cleaned the parts up like new, applied the sealant, put back together & re-installed on the truck. He is going to allow it to dry the remainder of the day & apply another small bead around the stack to elbow joint & let that set over the weekend. Re-install the clamp Monday morning & we'll see what happens. The stack & elbow are as round as they can be. If they weren't, you couldn't put them together. The stack fully seats on the elbow too. You wouldn't think a fit that tight, with 6 inches of elbow inside the stack, would leak. But it does. IF this doesn't solve the issue, Lincoln Chrome will have to come up with something different!
    Last edited: Dec 11, 2020
    Klleetrucking and loudtom Thank this.
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