Relay value

[Geoff Weeks]

5 minutes ago, Joey Mack said:

Ok.. im sorry.  Im wrong about the diaphragm..  I guess all those times i was isolating a bad brake chamber was in error.. I will back out if this thread so as not to post incorrect statements.

Not really, if you changed the whole chamber, with a service 30/30 you will be changing the correct part. I still have E brake chambers that you can service the spring brake side, either diaphragm or piston type, but those are what? 30-40 year old? When did the "idiot proof" "sealed chambers come out?

 Diaphragms leak to the outside, the piston rod seals leak chamber to chamber, but with the idiot-proof chambers, the only way to fix is to replace the service 30/30. In the old ones you can take the big Phillips head screw off one piston, remove the interchamber rod and replace the seals, though not many did. 

[Xe18]

7 hours ago, Joey Mack said:

Is the data tag still on the valve? You may just have to remove it to I.D. it. Mechohaulic makes a good suggestion. At $600.00 i would take it apart and inspect it and clean it, and try to rebuild it. Is the air system Bendix or Wabco? 

Bendix

[Xe18]

8 hours ago, 67RModel said:

Did their price include installation or was that just for the part? Mack might be asking double what its worth. Get the part number off of it and see what one can be obtained for from an independent supplier.

Just part. Part# on the valve is Bendix T-5019505

[Xe18]

3 hours ago, mechohaulic said:

noticed no one questioned WHEN is the valve leaking ;; constant (shouldn't be) ; during service brake application or after service brake applied and released? might make a difference where the hunt starts.

Constantly no matter brake apply or release 

[mechohaulic]

37 minutes ago, Xe18 said:

Constantly no matter brake apply or release 

being a constant leak WITH  parking brakes set; I'd go with earlier post I wrote and look at the lower section of that valve. if you have a "helper" a quick check would be to BLOCK the wheels safely; release the parking brake unit having full air pressure and truck shut off ; have someone have their hand on bottom side of leaking valve ; helper in cab step on brake pedal; air leak changes /slows chances are it's the flat rubber diaphragm in valve. to replace bottom kit ::parking brake set ; make sure all air is drained from tanks. larger pair of snap ring pliers (also safety glasses on ) , remove the snap ring .valve assembly has slight spring pressure. important thing air tanks MUST be empty.

[Geoff Weeks]

21 minutes ago, mechohaulic said:

bchances are it's the flat rubber diaphragm in valve. 

In the link I posted to the Bendix "manual" on that valve, it is all just plain O rings, and the manual even lists the size, so you can go to where you buy O rings, and have them all before you start.

 There is a small chance that there is a small (internal) leak from the solenoid valve on the top, but think it is much more likely a piece of crud is stuck in the valve, disassemble, inspect and install new O rings. Cost would be the cost of the O rings, but if you have a good supplier, then less than $20 would be my guess.

Follow Mecho's testing to make sure it isn't some other valve backfeeding into this one.

edit:

If your a gambling man, leave the valve in place, don't mess with the top 1/2 and only take the snap ring off the outlet, and remove and replace the O rings that come out the bottom, clean the valve seat where the delivery valve seats. That is the most likely point of failure. Just two O rings.

Edited 5 hours ago by Geoff Weeks

[Geoff Weeks]

That Bendix number come back to the ATR-6 which is what I posted the manual on.

[Xe18]

1 hour ago, Geoff Weeks said:

Follow Mecho's testing to make sure it isn't some other valve backfeeding into this one

No delivery port on that valve I can test for backfeeding. I’m the diagram there are two delivery ports but one got closed off and other one connect to other valve by metal pipe.