What is this part?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by nikmirbre, Jul 24, 2021.

  1. nikmirbre

    nikmirbre Road Train Member

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    I assume it’s some type of valve with all the different types of lines going in there. It’s leaking air at the bottom. I changed a brake chamber thinking that was where the air was leaking from however, it’s coming from the bottom of this valve.....it’s under my 5th wheel... B3180889-6ABC-4B7B-802C-3839B14574FF.jpeg 7C7D0E62-15D3-40BF-A52A-B4B683B6167C.jpeg
     
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  3. AModelCat

    AModelCat Road Train Member

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    Looks like a relay valve. Where do the lines run to? Which side of the chamber?
     
  4. nikmirbre

    nikmirbre Road Train Member

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    Not sure what you mean by that. 801DF2FF-D6D0-44CD-A0F6-CE396462466E.jpeg 9BE18A58-DAEA-4E27-AFBD-5C4DED7495D0.jpeg
     
  5. AModelCat

    AModelCat Road Train Member

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    That looks like a combination relay valve with ABS modulators. The outlet lines, if you chase them, do they go down to the service port on the brake chambers?
     
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  6. nikmirbre

    nikmirbre Road Train Member

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  7. AModelCat

    AModelCat Road Train Member

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    Does air leak out the exhaust port all the time or just when the park brakes are released?

    Does the truck have traction or stability control as well?
     
  8. nikmirbre

    nikmirbre Road Train Member

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    just leaks from the exhaust port at the bottom when the park brakes are released. Yes it has traction control. I think I found the valve...I mean I think a KW dealer about 30 minutes away has one. Problem is I cant get an uber or a cab company from where I am. Im having to rely on Loves to go get it before the dealer closes:confused:. Its not allowing my brakes to release all the way.......
     
  9. AModelCat

    AModelCat Road Train Member

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    I'd try and pinch off the park supply line at each chamber 1 at a time and see if it stops. 9 times out of 10 when a relay valve leaks out its exhaust its actually the result of something downstream backfeeding air. I'm thinking you might have a leaking pushrod seal between the spring side and service side on one of the brake chambers. That would definitely cause air to backfeed and blow out the exhaust on the relay.
     
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  10. nikmirbre

    nikmirbre Road Train Member

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    Just so were clear...when you say park supply you mean the "service" line right?

    Pinch it off then release brakes and see if it leaks still? 1 chamber at a time....
     
  11. AModelCat

    AModelCat Road Train Member

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    Nope. Pinch off the line going into the parking port of the brake chamber (its the port closest to the back end of the chamber, where the caging bolt goes). Then release the brakes. If it stops leaking out the valve then you've found a faulty brake chamber.
     
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