Problem with 97 Kenworth's red dash valve

[Woodlands]

My 97 Kenworth's red dash button won't stay in weather the trailer is hooked up or not... It just gets lots of back pressure. And I already changed the tractor protection valve.. nothing seems to work

 

[r3gulator3]

My 97 Kenworth's red dash button won't stay in weather the trailer is hooked up or not... It just gets lots of back pressure. And I already changed the tractor protection valve.. nothing seems to work

Does it leak air and then pop out or just push in and as soon as you let go pops out?

 

[Woodlands]

It leaks air as long as I hold it in

 

[mndriver]

chances are then you have a blown air line, air chamber or tank on the trailer then.

 

[r3gulator3]

Is all the air leaking in the dash or is there air leaking under the truck too like from a relay valve or a brake can?

 

[mndriver]

Prime example of why people need to be taught more about the mechanics of driving a truck and the actual systems they are pushing buttons on.

 

[Woodlands]

It leaks only out of the red line .... And if I plug the red line ..... And NO trailer is connected the button still won't stay in .... And it's got lots of back pressure.. could it be the brake pedal valve?

 

[r3gulator3]

unlikely. If the red line is capped off and it still won’t stay in. I’d lean towards a worn out dash valve.

 

[Woodlands]

I tried a new one and still no difference... Could it be a broken chamber on the truck if I'm having issues with the red line

 

[r3gulator3]

I tried a new one and still no difference... Could it be a broken chamber on the truck if I'm having issues with the red line

Yes that’s why I asked if anything was leaking under the truck.

 

[Woodlands]

Nope nothing at all

 

[r3gulator3]

Has anyone done any air plumbing on it before this started?

 

[Woodlands]

Yep I can build 120 no problem

 

[r3gulator3]

And on that note. Good luck in your endeavors.

 

[Humble pie]

One leaking chamber won’t cause the red button to pop out.

 

[Shogun Warrior]

No, the red button only controls the emergency side for the trailer.

Are you able to build atleast 90 psi in the truck?

Are you a certified red button tech?

 

[Shogun Warrior]

Yes. I've been a red button tech for 20 years, I'm working on my yellow button cert renewal this year.

I choose to drop my blue button certification because lack of blue button usage in trucks nowadays.

I'm OUT!!!

 

[Johndeere4020]

@Woodlands lets try going to the valve in the dash and unhooking lines to see where we have pressure and where we don’t. I feel like we have something back feeding.

 

[Humble pie]

It sounds to me like it’s the manifold valve. I thought I read where you replaced it, I see it was the protection valve that you replaced. I would say that’s where I would start.

 

[Humble pie]

You can get a kit to rebuild it for 50ish bucks or replace the valve. They aren’t cheap 3-500 bucks.