International prostar brake locks up ...read!

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by tipto3, Jun 12, 2024.

  1. tipto3

    tipto3 Bobtail Member

    4
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    Sep 6, 2021
    saratoga california
    0
    Hey guys need help
    I have a day cab prostar with an Eaton auto shift...bought it , test drove it about 3 miles brought it home...the the next day I tried to drive it I put the truck in reverse and it rolls back about 10 ft and the front brake locks up without touching the pedal...confused I turned the truck off and tried again....truck rolled about 10 ft and brakes grabbed again...so this time I actually press the brakes and I hear air release as I step on the brakes and the truck rolls freely once I release the pedal....this time it goes about 20ft and starts again...I've replaced abs valve under the cab..no major leaks truck did sit for a couple years no codes ...but on key power up position the modulator valves click and abs valve puff out air I don't recall my other trucks doing that ...I literally dont know what to do only thing else I see is some sort of I'm assuming electrical board screwed to the inner frame with air lines going to it dont know the same or its function...frustrated can anyone help out? Replaced the interior brake valve yellow and red knob...abs valve under cab was rebuilt the piston was siezed inside ...modulator valves pass chuff test no leaks when running ...at a loss right now...any feedback would be greatly appreciated
     
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  3. SomeCanadian

    SomeCanadian Light Load Member

    57
    80
    Nov 11, 2021
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    I’m not a mechanic!!!

    If I read this right, your talking about steers.
    Rule out air, disconnect the lines. Put a pressure gage in its place?

    It’s a place to start…
     
  4. FLHT

    FLHT Road Train Member

    1,111
    1,674
    Aug 2, 2014
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    Sloan valve that distributes air to front brakes.
    If you start getting into the ABS stuff it is very expensive to change parts and hope thats it.
    Last time I bought a ABS brain it was just under $700.
    In the long run its cheaper to let Simone who knows what their dealing with.
    Good Luck
     
  5. Heavyd

    Heavyd Road Train Member

    7,651
    6,067
    Feb 4, 2009
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    When your brakes are locked on, follow the air line back from that brake to locate what valve is sending air uncommanded. Let us know what you find. I am not 100% sure what set up you have there.
     
    AModelCat Thanks this.
  6. tipto3

    tipto3 Bobtail Member

    4
    0
    Sep 6, 2021
    saratoga california
    0
    Oh so here is what I found ...bendix atr6 with the little solenoid on the top and also has 5 modulator valves...now the air line goin to the solenoid blows out air when I hit the brakes..testing and rolling with the air line unhooked (literally 1mph) the solenoid itself is now blowing air out of it! so now we have air coming out of the solenoid and the hose when the hose is supposed to go into the solenoid to provide air( I'm assuming)....it randomly activates and locks the wheel up not Everytime sometimes it's 20ft sometimes it's 1000 ..and when I tap the brake pedal u hear exhaust from the brakes and it releases instead of letting off and hearing exhause..they are air disc in the front...abs was rebuilt because of this and no cure.. when the brake pedal it pressed there is air coming from the exhaust and when pressed harder it doesn't leak ....
     
  7. tipto3

    tipto3 Bobtail Member

    4
    0
    Sep 6, 2021
    saratoga california
    0
    Well I can get the parts very cheap noone knows much about this it came from the dealer unfixed Im not to smart when it comes to brakes ..u're telling me I can have a bad computer with no codes? I have neds and all the software getting the parts is the easiest part I just don't know where to start ...the shop just left me hanging said it was fixed and I drove away and it locked up right about a miles away
     
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