Need help identifying an air valve.

[buswarrior]

There is a problem with only changing the insides, and getting short cut advice from fleet mechanics.

Our buses are old, and often found in horrible conditions that a fleet mechanic has never seen.

If there is any corrosion inside that valve body, replacing the moving bits may not last long, if at all.

Compatibility between generations of valves can cause trouble too.

Some busnuts cannot afford $$$ to experiment, spending twice for the same problem.

Nothing is easy on an old, worn out, discarded commercial vehicle...!

happy coaching!
buswarrior

[B_K]

"Broken.

Change it out.

Be prepared to use the penetrating oil of your choice and leave it to soak in, both airline and bracket fasteners."


That's what I am trying to say with my first post. Release all air pressure. Remove the circlip that you can see in the photo, and replace the plastic innards and o rings with ones from a new valve. Leave the old valve body in place. save yourself the trouble mentioned above.  I got this trick from a long time bus mechanic who services hundreds of passenger coaches per year. Yeah, you end with a useless new valve body.

Wow I just learned a new trick.

And yes Buswarrior has a good point too. However this time I am going to side with the Richard & fleet mechanic as IF while changing out the internal parts of the valve you carefully clean and inspect the the valve "body" itself all should be OK.
However if it does not work when done it's easy to go back remove the internals and replace the valve "body" with the new one with the internals re-installed and only a slight loss in time & labor.

Could that valve effect the airbags and or possibly make the emergency brake pull lever have a red ring when it's engaged?

I have a different coach, but I have learned that, for me...It's all connected. If you have to change it anyway, change everything around it made of rubber more than 5 years old.

I don't think it would have a DIRECT effect on the airbags. However the fact that it leaks to the point where he's not getting over 90 psi which is usually when the accessory systems start filling on most coaches that could in fact have an effect on the airbags and other systems since they are on the accessory side of the air system.
(clear as mud?)
  BK 

[daddysgirl]

BK: Clear as spring water...or possibly 40W 

But because this is an air valve, and given its location, wouldn't it be easier to replace it as a unit? Old one out...new one in?

[peterbylt]

I want to thank everyone for the Replies, advice and knowledge.

I will be replacing the entire valve.

I am not under any time constraint or in a compromising or emergency situation, would hate to drop and lose an o-ring or circle clip trying to save a few minutes.

Might as well take advantage of a completely new valve.

I just got off the phone with Luke from US Coach, a new R-12 relay valve has been ordered and is on its way.

Luke agreed with our assessment that the Relay valve is the issue.

Once I have this air leak repaired, I can start chasing down the air leaks that I can't hear....   

Peter

[RichardEntrekin]

All good points on the merits of either approach. And thanks to everyone for keeping the differences in thought civil.

[eagle19952]

"Broken.




That's what I am trying to say with my first post. Release all air pressure. Remove the circlip that you can see in the photo, and replace the plastic innards and o rings with ones from a new valve. Leave the old valve body in place. save yourself the trouble mentioned above.  I got this trick from a long time bus mechanic who services hundreds of passenger coaches per year. Yeah, you end with a useless new valve body.

uhm...more often than not the seats and valve body are worn too...

[easystreet]

Good choice to replace the entire valve. The snap ring at the bottom will not get you to all of the moving parts anyway. The top cover must also be removed as that is where the large piston (with o ring around the outside) is located. That piston is what the control air pressure is applied on top of to push the piston down and open the supply air pressure port to the outlet ports. Essentially the same thing you do when you step on the treadle / brake valve with your foot. You step on the brake valve at the front and send control air to the relay valve, that in turn sends air to the brake chambers. 

[eagle19952]

Clear as spring water...or possibly 40W  

But because this is an air valve, and given its location, wouldn't it be easier to replace it as a unit? Old one out...new one in?

the pain arises when one does not clearly note/know which fitting went where, what angle they need to be at, if the threads are deeper and the last 1/3 turn you need to clock the fitting is going to strip...or which ports are plugged.. then the doubts arise about sealant and someone saying Teflon tape is better than dope... the list goes on.... and on ... i am a doper with a bent for complete replacement including new fittings ( this leaves no doubt as to what went where...then there is the matter of replacing the hoses while i'm there.... ...using a minimum 40 lb. vice properly mounted to a 4x8 3/4 inch steel plate bench...

[Jim Eh.]

Hang on.

This coach has DD3 parking brakes.

Remove nothing. Block the wheels so it won't roll.

Air up the coach.

RELEASE the parking brake, and see if the relay valve is leaking differently from with the parking brake APPLIED.

If a DD3 chamber has a bad parking diaphragm, it will leak when parked, and won't leak when released.

Jim Eh, yours works for spring brake chambers.

happy coaching!
buswarrior

Regardless if it is a spring brake chamber or a DD3 if the pushrod seals are leaking it will exhaust air out the service relay exhaust port! I said nothing about a leaking diaphram. If the diaphram is leaking it will exhaust air from the small holes in the pot housing and in the case of a spring brake, also out the caging bolt hole.
The test was if the air leaked only when the parking brake was released. I did however forget to pass on the obvious information about safety.