Drain Plug Sealing

Discussion in 'Oil' started by badbmwbrad, Nov 11, 2014.

  1. badbmwbrad

    badbmwbrad Member

    My new-to-me Fat Boy had some white-colored pipe thread sealant on its three oil drain plugs (engine, chain case, transmission). Each plug also had an O-ring. The transmission O-ring was broken and caused the plug to be under-torqued.

    I'm not sure any of these threads are tapered. If no then pipe thread sealant is inappropriate here. The sealant can get inside the engine's oil passage, block oil flow and result in damage.

    I think it's better to simply replace the O-ring every time the plug is removed and don't over-torque the plug.
  2. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

    That's the way to do it. No Teflon tape or thread sealant paste. Not needed if the o-ring is good. I just snug mine up handy (finger tight) and then a bit more with the wrench (1/6 - 1/4 turn).

    On my last bike ('03 Ultra) and the '91 Dyna, they had a pipe plug in the primary case drain. I did use Teflon tape there, but only on the threads not letting the tape excess on the inside of the case.


  3. Jeff Klarich

    Jeff Klarich Well-Known Member Contributor

    Permatex thread sealant works well but it's a good idea to change the O ring for if any reason gives you piece of mind. I'm with TQ, I don't torque everything, tight is tight.
  4. Jack Klarich

    Jack Klarich Guest

    Harley Davidson Forums
    You may try some of this, yes pipe thread is tapered, I use a new O ring each time tor peace of mind, Your ride you decide IMO:s