Replace Air Regulator???

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by wjhuskey, May 15, 2024.

  1. wjhuskey

    wjhuskey Bobtail Member

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    Nov 1, 2014
    Arkansas
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    Hello guys. I have a 1993 Peterbilt 379 project truck and it's been setting for a couple years but finally getting around to working on it. The brakes have always made a steady "air horn toot" sound as soon as you press down on them (not the usual air sound when letting off). When I started it the other day, I noticed the air compressor regulator/governor on the side of the engine was spewing air. The truck has always had trouble building air. I plan to pick up a new regulator in a couple days. Could this be why the brakes have always made this sound?
    If not, what should I check? A valve???
     
    Last edited: May 16, 2024 at 1:03 AM
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  3. BoxCarKidd

    BoxCarKidd Road Train Member

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  4. Sm0kie

    Sm0kie Bobtail Member

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    May 15, 2024
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    Doubtful. In my experience older trucks just do that. Might be style of chambers you have
     
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  5. wjhuskey

    wjhuskey Bobtail Member

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    Nov 1, 2014
    Arkansas
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    I've got 2 other trucks this age (another '93 and a '92), neither make this sound with the brakes
     
  6. RocketScott

    RocketScott Medium Load Member

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    Mine's an '89 and doesn't make that sound. Probably a relay valve sticking or a tear in one of the chamber diaphragms
     
    BoxCarKidd Thanks this.
  7. BoxCarKidd

    BoxCarKidd Road Train Member

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    Two people to chase the noise would help.
     
  8. Smellfunny

    Smellfunny Road Train Member

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    I would think it would be the air blowing out of one your exhaust ports. Either the service valve or your foot valve. Like BoxCarKidd said. Two people to chase it down.
     
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