Pto fudgeup trouble shoot 1/2 way point

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Breakingbaf, Jul 18, 2021.

  1. Breakingbaf

    Breakingbaf Bobtail Member

    3
    0
    Jul 18, 2021
    0
    Stats :
    1990 peterbilt triaxel 16ft bed
    Eaton 10 speed
    3406b cat
    red 8 bolt pto ( looks newer)
    Hyd pump gray (looks og to truck ); 2 air lines ; 2 hyd hose intake outtake
    Driver whose moderately experienced but also gets in the clouds sometimes

    Ok — so got distracted by roadside food stand after leaving gravel lot beside each other hilarious I know . Drove with pto for 20 min at 35-45 mph .

    got to site — no dump raise .
    So flipped it to lower for the the hell of it . Got a grinding noise (will try to post video ) edit (— post your email and I can send it that way this site isn’t having it )

    talked it over with a friend — more likely that I burned the pump up vs pto gears .
    So took off pump ( dam that’s heavy ! )
    Turned the gear spines manually but no sound. Looked clean ; slight friction .

    got in and tried to engage pto to see if grinding or chattering persits— no sound and also no movement of pto ( I looked best I could with flashlight . )


    To add a further twist — I recall a similar noise 3 days ago as I was lowering the bed — and it stopped 1/2 way down.

    so now I’m confused …. Is the pto now not working because theirs no air vacuum since pump and all lines are off ?
    Really just trying to figure out what to order first ?

    pto or pump ?
    Ideas ? Thanks for helping a teacher turned trucker !
     
    Last edited: Jul 18, 2021
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

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

  3. Big Road Skateboard

    Big Road Skateboard Road Train Member

    4,320
    20,518
    May 2, 2021
    0
    With PTO switched on (need air of course) you should not be able to move the output shaft. If you can move it when switched on or off, you have an issue with drive gear or sliding lunch most likely.

    If it locks up when engaged, issue is likely in the pump.
     
  4. AModelCat

    AModelCat Road Train Member

    27,626
    144,548
    Jul 7, 2015
    Canuckistan
    0
    Hydraulic shop. Its cheaper to test the pump than to replace it on a hunch if you're wrong.

    I don't see a PTO or pump getting burnt up simply by driving with it engaged. Most of those systems are open center, so oil will just flow back to tank.

    You mentioned the box stopped halfway down prior. Every dump truck I've come across is just a single line cylinder and its gravity that lowers the box, not hydraulics. I'd start with looking at the control valve. Might be sticking or bypassing.
     
    Breakingbaf and lester Thank this.
  5. Breakingbaf

    Breakingbaf Bobtail Member

    3
    0
    Jul 18, 2021
    0
    Ok so Took part two hydraulic shop any car was really helpful took it apart – we’re both surprised that it wasn’t completely fried on the inside – no burn marks – but definitely worn and had a Miller meter dash very small ring worn around in full circumference of one of the shiafts — So it seemed like it was dying a slow death and I sped up that death. Cost to rebuild versus buying a new one made me want to buy a new one.

    however my Conversation with him now has me confused. The original pump in the new pump takes two airlines. Which I have and see. However the PTO that is on my truck has not had an airline on it. But the guy said there should be one on the PTON it’s a Chelsea by the way. Another guy the shop told me that sometimes the airlines to the pump actually act to pressurize the vacuum for my PTO in the pump – but the physics of that do not add up in my opinion. What do you think see pictures.? In blue link — Thanks for all the help only owned truck a month
    E0-FC949-E-64-BA-4-C27-B88-B-04-A918-F32-EF9
    634-DA97-F-50-C6-42-FB-BB94-0715-E05-A1-D1-A
    327435-B6-B5-F0-4-E54-83-A6-FF65-ABE148-C0
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

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