Truckers Report Jobs

Find Trucking Jobs

Company Driver Company Driver Dry Van Dry Van Flatbed Flatbed Refrigerated Refrigerated Specialized Specialized Owner Operator Owner Operator
More Trucking Job Searches ⌄ Fewer Trucking Job Searches
⌃

the importance of running overhead adjustments on deisel engines

Discussion in 'Trucks [ Eighteen Wheelers ]' started by michael jennings, Jul 25, 2012.

Page 1 of 2
  1. Jul 25, 2012 #1
    michael jennings

    michael jennings Bobtail Member

    1
    0
    Jul 25, 2012
    0
    I have been around the trucking industry for 30 years. I am now General Manager for three towing companies in the Little Rock area. We have a variety of trucks from Sterlings with the mercedes MBE 900 engine Peterbuilts with Cat and Cummins engines and even a couple of Hinos. What I would like is for someone to explain what it is to run a overhead o a deisel engine and the importance of such a procedure.
     
    michael jennings, Jul 25, 2012
    michael jennings, Jul 25, 2012
    #1
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

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

  3. Jul 25, 2012 #2
    Shaggy76

    Shaggy76 Heavy Load Member

    831
    307
    Feb 22, 2012
    Orlando, FL
    0
    Overheads adjust your valves to prevent premature leak outs of exhaust, loss of cumbustion, seal for intake, plus many other factors. Over time, your valves will stretch, the cam lobes will wear, the lifters will wear which causes tiny gaps between the valve head and the valve seat. Depending on the wear, somd engines can gain approx 20% of their power back and fuel mileage increases up to 1 mile per gallon. I've done some that only needed small adjustments and some that were drastic.

    I remember one in particular that had 750,000 on N14. Other tech thought injectors were bad due to severe power loss. I did the overhead with Jake brake adjust and the difference was very noticeable. Needless to say, the injectors were fine.
     
    Shaggy76, Jul 25, 2012
    Shaggy76, Jul 25, 2012
    #2
    Ssgtkevin, Stringb8n, black_dog106 and 3 others Thank this.
  4. Jul 25, 2012 #3
    SL3406

    SL3406 Medium Load Member

    550
    1,491
    Jan 10, 2011
    Oklahoma
    0
    The overhead adjustment is setting the clearance between the rocker arms and the valve cross heads. As the valve and valve seat wear it allows the valve springs to pull

    the valves up further as it shuts the valve which over time reduces the clearance between the rocker arm and cross head. If the overhead adjustment is ignored for long

    enough the valves will no longer close entirely leading to accelerated wear in the valve train and even a burned valve. The fuel injectors are actuated by rocker arms on

    most newer engines and also need to checked for proper adjustment to account for wear at the same time.
     
    SL3406, Jul 25, 2012
    SL3406, Jul 25, 2012
    #3
    Ttimefr Thanks this.
  5. Jul 26, 2012 #4
    belltransit

    belltransit Light Load Member

    271
    27
    Jun 28, 2010
    oak grove, mo
    0
    on the acerts i was told they tighten up as they wear. if u dont keep up on the overhead u can have happen what happened to me...an intake rocker arm broke. when it went i would have swore the motor blew a rod thru the side of the block. i was told to have the overhead ran around 150,000 miles.
     
    belltransit, Jul 26, 2012
    belltransit, Jul 26, 2012
    #4
  7. Jul 26, 2012 #5
    Shaggy76

    Shaggy76 Heavy Load Member

    831
    307
    Feb 22, 2012
    Orlando, FL
    0
    On the ACERT intake tightens and causes valve slapping where exhaust loosens causing combustion leakage.
     
    Shaggy76, Jul 26, 2012
    Shaggy76, Jul 26, 2012
    #5
    Cam Roberts and Dark_Majesty_06 Thank this.
  8. Jun 5, 2019 #7
    Steppin on out

    Steppin on out Bobtail Member

    3
    7
    Jun 5, 2019
    0
    If you got an acert your problems are much greater than overhead lol
     
    Steppin on out, Jun 5, 2019
    Steppin on out, Jun 5, 2019
    #7
    Cam Roberts Thanks this.
  9. Jun 5, 2019 #7
    swaan

    swaan Road Train Member

    2,942
    4,374
    Jul 12, 2009
    BC canada
    0
     
    swaan, Jun 5, 2019
    swaan, Jun 5, 2019
    #7
    Oxbow, spsauerland and SL3406 Thank this.
  10. Jun 5, 2019 #8
    25(2)+2

    25(2)+2 Trucker Forum STAFF Staff Member

    18,756
    45,795
    Sep 18, 2006
    the road less travelled
    0
    The valve train tightens or loosens, depending on which, the last one I had done was on a 14liter 60 series, the valve train actually broke, and it was not hitting on very many cylinders, sounded like a 2 cylinder John Deere.

    No codes thrown, straight mechanical failure, drove it to the nearest dealer. No further damage noted.

    Leased trucks fixed at discretion of the owner.
     
    25(2)+2, Jun 5, 2019
    25(2)+2, Jun 5, 2019
    #8
  11. Jun 7, 2019 #9
    starmac

    starmac Road Train Member

    6,639
    12,528
    Apr 11, 2019
    Fairbanks Ak
    0
    The valve lash pretty much tightens up on all diesel engines, when they start wearing the valve seats and or the valves themselves.
     
    starmac, Jun 7, 2019
    starmac, Jun 7, 2019
    #9
    swaan Thanks this.
  12. Mar 31, 2020 #10
    Mcast3092

    Mcast3092 Light Load Member

    137
    107
    Jul 31, 2018
    0
    How often should you get overhead adjusted?
     
    Mcast3092, Mar 31, 2020
    Mcast3092, Mar 31, 2020
    #10
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

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

    • Page 1 of 2