1998 379 break relay leaking constantly

Discussion in 'Peterbilt Forum' started by tmslogistics, Mar 10, 2015.

  1. tmslogistics

    tmslogistics Light Load Member

    138
    15
    Mar 10, 2015
    0
    1998 379. Valve at rear drive axle cross member....abs relay combo valve purging air when I release the tractor breaks. So I replaced the entire valve and abs relay assembly. Still leaking from the bottom center of the valve. This has been a gradual issue. At first, months ago, I would release tractor breaks and it would take a second for something to catch and then the tractor breaks would release. Now....when I push in the tractor break button it constantly leaks from this valve. I'm at a loss. Any help will be greatly appreciated.

    Thanks,
    Toby
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

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

  3. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

    1,778
    1,722
    Jun 14, 2009
    romulus,mi
    0
    QR-1 valve.Located under your fifth wheel.Follow the air lines from brake chambers.Only about $25.good luck.
     
    tmslogistics Thanks this.
  4. tmslogistics

    tmslogistics Light Load Member

    138
    15
    Mar 10, 2015
    0
    Already replaced it when I replaced the abs modules and the valve in the middle. The brake lines coming from the chambers tie into the abs module. There's an abs module for each side....right and left. The bolt onto to the brake relay/purge valve. So.....there are actually 3 pieces/valves under fifth wheel on the cross member above the rear drive axle. All is brand new.
     
  5. tmslogistics

    tmslogistics Light Load Member

    138
    15
    Mar 10, 2015
    0
    Tractor brakes will not release.
     
  6. BoxCarKidd

    BoxCarKidd Road Train Member

    4,167
    5,981
    Aug 26, 2014
    0
    Maybe unhook service lines from brake chambers, should be marked, and farthest from slack adjuster. Release the brakes, if air comes out of one of the chamber ports its bad. If their rubber hoses you can just pinch then off one at a time with flat nosed pliers one at a time. Use chalks don't get rolled over.
     
    tmslogistics Thanks this.
  7. tmslogistics

    tmslogistics Light Load Member

    138
    15
    Mar 10, 2015
    0
    The qr1 valve is on the front drive axle....not the rear drive axle. Correct.
     
  8. beltrans

    beltrans Medium Load Member

    441
    101
    Nov 26, 2008
    spokane wa
    0
    I had same problem while ago.. I replaced a quick release valve just above front axle.. that was it..
     
    tmslogistics Thanks this.
  9. tmslogistics

    tmslogistics Light Load Member

    138
    15
    Mar 10, 2015
    0
    Beltrans,

    So......just to make sure we are on the same page....the valve at the rear axle was leaking off. So you replaced the valve on the front axle, the qr1, and that solved your problem?

    Thanks for your help everyone.
     
  10. brysol01

    brysol01 Medium Load Member

    309
    431
    Nov 2, 2009
    0
    internal Maxi chamber leak ??
     
    beastr123 Thanks this.
  11. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

    1,778
    1,722
    Jun 14, 2009
    romulus,mi
    0
    QR-1 valve on front drive.That's what I said (meant)Good luck.
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

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