Sunday, October 9, 2011

Air brake issues hanging like a dark cloud over me.


I have removed, inspected, and reinstalled the QR1 valve numerous times over the past several weeks.  Since I had not made an progress I saw no sense in making blog posts.  I am trying to figure out why I still have a slight air leakage out the exhaust port when the parking brake is applied.  I looked at other parts of the air brake system and found the parking brake (push-pull) valve leaking out the bottom so I ordered a new one from Luke @ U.S. Coach for about $115.  I feel that most of the parts I have had to replace on the bus, so far, have been fairly priced especially considering their size.  The one part that is priced like gold, however, is TIRES.  I'll get back to that topic though in another post to come later.

Yesterday I attempted to replace the parking brake valve shown in the picture to the right.  It has three air lines that were originally copper.  This valve fits in a small compartment to the right of the driver next to the transmission shifter and access is made more difficult by the fact that the driver's seat is right next to it.  I attempted to install it twice.  I never did have much success getting it lined up to fit in the bracket mostly because of the rigidity of the copper lines and also because the new valve threaded top is just slightly larger than the original one and doesn't fit in the hole in the mounting bracket.

So today I removed the three copper air lines completely, marked them as to location and purpose and this week I will go get some plastic DOT air line to replace them with.  This will be much more flexible and the reinstallation of the valve with the new air lines should be a piece of cake.  I drilled out the mounting hole just a bit and now the threaded top of the new valve fits in the bracket perfectly.

Before I removed the valve though, I started the bus and ran the air system through its paces to listen for other obvious air leaks and check the operation of the air dryer purge valve and the cut-in/cut-out pressures on the air governor.  I could hear a decent air leak from around the rear axle which makes me think further that I have one of more brake cans leaking in the rear.  My thought is that the slight air leakage I still have up front in the QR1 valve is possibly coming from the same rear brake cans.  It seems so much of the time I get one step forward and then take two back.  None of this will fix itself and I keep saying I should be thankful to find this stuff now at home base than in the future on the side of the road.


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