Air brake systems and diagnostics

[doublewide]

..... check valve should be present that prevents primary or secondary air from leaking to another tank.

Check valve bad from wet tank to the next tank?

Check valve. That was my guess. If the check valve at the secondary tank is malfunctioning, air can leak back to the wet tank and then out through the leak at the rear axle primary tank.

 

[doublewide]

Still waiting on parts...

 

[Tags]

That looks like she's cold and lonely....

 

[doublewide]

.... That was my guess. If the check valve at the secondary tank is malfunctioning, air can leak back to the wet tank and then out through the leak at the rear axle primary tank.

Bingo! New check valve solved the problem.

 

[doublewide]

So, despite having installed a new seal kit in the PP-1 valve I continued to have excessive air loss out the exhaust port. What good are new seals while reusing the old spring? I think that was an exercise in futility. I ordered a new valve. That's what has taken so long to come in.

A little project between turkey and punkin’ pie.View attachment 228730

 

[Birken Vogt]

I don't know your exact situation here, but as a general rule, if air leaks out the exhaust port, often it is coming from some other source upstream, leaking by, and the valve is just doing its job. Is it possible the air being released from the PP-1 itself, or is it coming back from a leak in a relay valve, for example?

You would disconnect the delivery port line from the PP-1 to check for this, not under pressure, of course.

As a general rule I don't rebuild components of this type, just buy new or rebuilt ones.

 

[doublewide]

I don't know your exact situation here, but as a general rule, if air leaks out the exhaust port, often it is coming from some other source upstream.....

Yes, I did think of that;

 

[doublewide]

I did investigate whether air was leaking back from the R-7 valve. I cannot guarantee that is not the case but I decided to make a corporate decision and replace the PP-1. Now I have a new PP-1, PP-7, new TP-5, at least half of the air lines are new and the R-7 is only a year and a half old. I can now be fairly certain that I won't have to get back into the dash portion of the project.
After connecting the valve assembly today I no longer have air leaking from the exhaust valve. Air loss was 25 psi over an hour and a half with the PP-1 pushed in, spring brakes in the hold off position, engine off. I'll check it tomorrow with parking brakes applied.

 

[Birken Vogt]

Yes, what that guy did was exactly what I was thinking.

 

[doublewide]

Time to pay some attention to the service brake chambers.

 

[doublewide]

According to my measurements these are type 16 service brake chambers.

 

[doublewide]

Confirmed. Midland T - 16.

 

[doublewide]

Midland N-20151 T -16.
https://mpparts.com/part/midland-n20151-type-16-air-brake-diaphragm-n20151
or
https://www.finditparts.com/product...0 X2lkeCI6MH0= &ga_list=Search Autosuggest v2

 

[doublewide]

These are shot.

 

[doublewide]

It looks like the band clamp style has changed to a two bolt style. Can anyone tell me if they are universal and if these would be a suitable replacement?

https://www.finditparts.com/products/364920/haldex-cb16

 

[Truck Shop]

Yes. Sometimes easier to replace whole air chamber. IMO

 

[doublewide]

Yes......

The 2 bolt style I linked to above is a suitable replacement. OK, thanks Truck Shop, I appreciate that.

.....Sometimes easier to replace whole air chamber. IMO

I just may do that. I will pull the other side chamber and evaluate it's condition. If poor, I will replace both with new. Thanks again.

 

[doublewide]

Picked these up locally.

 

[doublewide]

https://cbsparts.ca/admin/bulletins/PUSH ROD CUTTING PROCEDURE.pdf

 

[DMiller]

Figure Base to Clevis on Old Chambers, set up New ones for Same Length, Stroke distance from Not Applied position off the S-Cam can support mount has to remain the same. Major point is at Full apply after base Adjustment, the S-Cam and Slack Adjuster cannot pass 90 Degrees when applied for maximum applied pressure(Best Braking Force). There was a reason the old units had that Oval Stagger section of Can off the Cam Support Mount.