Eaton 18 spd oil at shifter knob

Discussion in 'Western Star Forum' started by uncleal13, May 17, 2016.

  1. Mythandar

    Mythandar Bobtail Member

    May 18, 2016
    The most common cause for this is the splitter in the transmission. Oil gets past the o-rings in the splitter cylinder and works it's way up to the shifter. This is usually caused by a slight pressure buildup at the splitter shaft when shifting which helps push oil past the o-rings. There is a fix for this which involves removing the splitter cylinder and drilling a hole through it about halfway down it's length. To verify that this is your issue just remove the little blue air line from the back of the transmission (lower left), if there's oil in it then this is the cause. If you wanted more proof then you could remove the air line that feeds air to the transmission's pressure limiting valve and see if there's oil there, it'll be on the upper right of the rear of the transmission, there'll be 4 air lines there, 2 run up the side of the transmission, 1 drops under the driveshaft to the splitter, and the other will run to the framerail, the last one is what your looking for. I suspect it'll be dry but your little blue air line will have oil in it.
  2. Bledi

    Bledi Bobtail Member

    Mar 16, 2019
    Hello everyone
    I have the same problem on 13 speed transmission,oil leak at the knob,i fixed at the mechanic twice,it was working fine for only 2 mounth and the problem started again,i dont know where this oil is coming from at the knob,and what it does is that when i move the splitter from front to back it makes a wird noise like the fluid is passing through the line.
    If anybody has an idea what’s going with this issue?! Please help
    Thank you
    Last edited: Mar 16, 2019
  3. importvic

    importvic Bobtail Member

    Apr 22, 2013
  4. importvic

    importvic Bobtail Member

    Apr 22, 2013
    Experiencing the same exact problem. I bought a 2013 Cascadia from Lone Mountain Truck a few years back. Originally a 9-speed converted to a 13 speed. Don't know if that matters. It's been doing this for a few months. Does the squishing sound when thumbing back on the splitter. Thought shifter was going bad so just replaced with a new one and noticed all the oil when I pulled down the plastic sleeve. What ended up being your solution? Or if anyone else can chime in on the cause & fix I'd greatly appreciate it. Thanks!
  5. Mr Bob

    Mr Bob Light Load Member

    Mar 17, 2015
    I realize this is old but do you more details on the hole drilling?
  6. Star4900

    Star4900 Medium Load Member

    Mar 16, 2015
    Northern Ontario
    Both our new Stars do this. I just stuff paper towel or kleenex inside the bottom of the shifter handle, LOL

    My new 2020 just grenaded it's Eaton 18 speed at 30,000 KM, LOL

    Apparently a piece of a bearing retainer broke off and passed through the synchros.

    Happened fast too. I was driving along empty at 60 KPH and by the time it started making a "whirring" noise. the shifter started to shake and BANG! No high range gears.

    Eaton sending a new trans. Been a long long time since I ever heard of a trans failing.
  7. AModelCat

    AModelCat Road Train Member

    Jul 7, 2015
    The North
    When I worked on trucks we had one truck in the fleet #### the lower countershaft out thru the case and onto the highway.
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