Differential rear axle fluid level

Discussion in 'Ask An Owner Operator' started by Rob2isking, Sep 28, 2020.

  1. Rob2isking

    Rob2isking Light Load Member

    108
    23
    Apr 30, 2015
    0
    Should you check the fluid level on drive axles with or without a trailer? I checked and it shows that it’s low with trailer. When I dolly off of it the level is fine. I would think you should check without the trailer. Does it matter?
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. not4hire

    not4hire Road Train Member

    7,142
    26,946
    May 16, 2012
    Calgary
    0
    Huh? That's a new one on me.

    The fluid level in the axle doesn't change according to load. The only way you're going to get a difference when measuring is if there is some rotation of the axle unloaded vs loaded... and I just can't imagine it would even be noticeable unless something is broken.

    I'm guessing a more likely scenario is the two checks were done in different locations and one had a slight slope to it.

    So, to answer your question: level ground, trailer or not shouldn't matter, but there's no trailer attached when the truck is built.
     
    Crude Truckin' and Socal Xpress Thank this.
  4. Rob2isking

    Rob2isking Light Load Member

    108
    23
    Apr 30, 2015
    0
    U checked last weekend. Had the trailer n load on. It was weekend and I’m off I grease n check things. Checked the rears Took plug out n stuck finger in n could feel barely at tip. So I added some to the plug level. Drove it all week. This time decided take trailer off cuz easier to get to. Took plug off and big stream started pouring out. Opposite of what I would’ve expected
     
  5. Roberts450

    Roberts450 Road Train Member

    2,237
    3,634
    Feb 6, 2016
    0
    Like @not4hire said only way that could happen is if the axles had rotated so when you checked it with the trailer hooked up was the suspension air bags filled up?? If not they will rotate forward causing the pinion to drop and the oil level to be lower since the plug is now rotated higher then its normal position when the suspension is aired up.
     
    not4hire Thanks this.
  6. DaytonTD

    DaytonTD Light Load Member

    161
    181
    Jul 14, 2019
    Edmonton, Alberta
    0
    Maybe you checked it when it was warm or hot versus cold
     
    InTooDeep and not4hire Thank this.
  7. not4hire

    not4hire Road Train Member

    7,142
    26,946
    May 16, 2012
    Calgary
    0
    Combination of those things plus, possibly, slope as I mentioned, although fluid expansion is only about 4%/100*F. Add them all together in combination though and you can get "tolerance stacking."
     
    AModelCat Thanks this.
  8. AModelCat

    AModelCat Road Train Member

    27,627
    144,553
    Jul 7, 2015
    Canuckistan
    0
    Flat, level ground. Suspension aired up and axles not under stress/torque is how I've always checked.
     
    not4hire Thanks this.
  9. feldsforever

    feldsforever Road Train Member

    1,453
    1,440
    Nov 22, 2019
    0
    Did u add to much? What's the proper procedure?
     
  10. Rob2isking

    Rob2isking Light Load Member

    108
    23
    Apr 30, 2015
    0
    I checked it when it was cold and air bags were up. I had checked it cold the weekend before. But bags were Down plus had trailer on
     
  11. DaytonTD

    DaytonTD Light Load Member

    161
    181
    Jul 14, 2019
    Edmonton, Alberta
    0
    If you had bags down the second time its going to change the axle rotation a few degrees. Check and fill it while it is cold and with the bags aired up to simulate the position it will be when its driving.
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.