R12-DC relay valve

[rwc]

After I shut down I hear air leaking from this valve. My right side air bags go down very soon after shut down Left side stays up for weeks. The air is coming from the small hole you see in the valve. Is this an R12-DC relay valve. My air schematic is not clear to me. Can it be rebuilt or should I just replace It. This is 102D3. Thanks Rod

[wildbob24]

Rod,

That looks like a pressure regulator to me. Probably a hole in the diaphragm. I'd just replace it.

The relay valve is the big square thing next to it.

Bob

[luvrbus]

That is a pre set regulator buy a new one

[rwc]

Thanks for the help.  Rod

[bevans6]

I have several regulator valves on my bus, doing different things - all the same regulator and all set to different pressures.  I carry one spare, and I set them with my shop air compressor and a pressure gauge.  You will need to know the pressure it needs to be set at, it may be on a tag or in a manual.

Brian

[rwc]

It has tag that I can read now that it is off. Parking brake 85PSI. MCI does not have it in stock. Where else can it be found. It is a Williams Product.  Thanks Rod

[luvrbus]

Any truck place can match it nothing special even a good Napa guy can order you one, TruckpartsforU have some on Ebay for 20 bucks each

good luck

[bevans6]

$20 is a great price, I got a rebuild kit from Luke and a new one.  Parking brake regulator reduces the pressure to the inversion valve so when you set the parking brake you never get more than 85 psi so you can always un-set them with the service brakes, it also regulates the air to the locking port I do believe.  It has nothing to do whatsoever with the suspension, so may not help your suspension leakdown problem.

Brian

[Tony LEE]

Airbag problem is unrelated so you may have a hole in the air beam, pinhole in the airbag or mounting flange or faulty levelling  (ride height) valve

[bevans6]

The part number is WM-279-E1, and they don't come set to any pressure - you have to screw in the adjusting nut and measure 85 psi at the output port. 

Brian

[buswarrior]

Yes, the pressure regulator in question is what limits the pressure sent to the DD3 chambers, via the inversion valve, both parking and locking portions.

One of the causes of difficult parking brake release is this regulator allowing higher pressure through.

Another device which simply should be changed out for preventive maintenance, as you get to it, if you do not know its age.

They can be set garage-gorilla-style by screwing a male airline fitting into the exhaust and using your tire gauge to set the pressure. If in a bind, you can even use the coach's own air supply.

For the long haul, be sure to lubricate the moving parts and fastening threads with the corrosion protection product of your choice.

happy coaching!
buswarrior

[rwc]

Thanks for all the help. Ordered new valve today. Will find some one to help adjust it to proper pressure. My tag says 85PSI but mechanic at Hausman in Dallas says 60PSI. Will have to do some more research on this before I re-install it. Thanks  Rod

[bevans6]

85 psi is correct.  60 psi will work but will not apply the correct parking brake application pressure.

Brian

[buswarrior]

oh crap, yes, 85 lbs for a 102D3! If not more!

Check the reference materials for that coach in case a previous owner installed one of the wrong value.

Call MCI if you have to and have them look it up, if you don't have the book.

Perhaps the mechanic thought you were talking about something else?

We'll hope so...

60 lbs is way too weak for a 40 footer.

happy coaching!
buswarrior

[Tony LEE]

My tag says 85PSI but mechanic at Hausman in Dallas says 60PSI.

Maybe mechanic has never heard of DD3 brakes and thinks you have spring parking brakes

My right side air bags go down very soon after shut down Left side stays up for weeks.

Did you look at this part of the problem yet