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Cycling Air Gauges
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I replace mine at 6 years of age all four of them , no matter what , they are cheap, the rubber o rings go bad or they get dirt in them , I carry one R14 with me and one rebuild kit for the rest , very easy to rebuild take out snap ring and replace all the guts five minute job
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I appreciate all the help. I am in contact with Ft. Worth Prevost and will let you know.
I missed this post when I checked in last night.
Davy, it could very well be the singnal air line going from the air compressor to the governor . Peter………
What is this?
Davy
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That could be on the list except they don’t repair themselves. I am pretty sure the issue was a relay valve.
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I emailed the only email address I had for Prevost Ft. Worth and it was fowarded to the Service Coordinator. He called me that day after running the description of my anomaly pass another guy in the shop. They were of the opinion that it was a fluke that merited close watching but probably not replacing at this time.
I consulted Jeff Rowe and he thought it might be a fluke but he considered it more of a warning sign. I called the Service Coordinator and set up an appointment for Tuesday to have the R-14 changed and the R-12’s that have not been changed previously.
I will arrived there Monday evening for my Tuesday morning appointment. They will be closed for Memorial Day but they gave me the gate code. Does anyone know if they have a dump station that is available outside of regular business hours at Prevost Ft. Worth?
Davy
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No idea about a dump station, but an observation about service life of parts and Prevost’s position relative to maintenance or service.
In my previous coach which was a similar vintage as Davy’s Prevost called for replacement of brake chambers annually or every 100,000 miles, whichever came first. The service manual was silent on other parts such as air bags and relay valves to pick two examples. When I questioned why they had that position I was told the normal practice was to replace those types of items when they failed.
Everybody has a different opinion of how their coach is to be maintained. That’s OK and I presume we decide how we need to maintain our coaches based on a lot of factors that influence our choice. But I was surprised at the posture Prevost had relative to air bags and relay valves (just to use those two as examples) because unlike a failed brake chamber, air bags and relay valve failures can disable a coach, where a failed brake chamber can be caged and air to it blocked so travel can resume, although with compromised braking. The other two failures can end up with a service call and a tow.
Davy is doing the right thing in my opinion because at the age of his remaining relay valves they are not far from being an issue and the relative cost of replacement is well worth the benefit received.
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Davy,
Prevost has a dump on the west side under the cover on the south side of the building. It’s set up for commercial buses, and as long as a bus is not sitting on top of it, you can use it. They work late hours, so access may be a problem.
We are headed up Wednesday to have them look at our air system on Thursday–our coach was doing the same thing as yours on the way back from the last trip. -
Thanks for the tip, Per. They will be closed this evening when I pull in so hopefully the station will be available. I must hit the road as soon as they finish so I will miss meeting you there.
Davy
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It is very late after a very long day at Prevost Ft. Worth. I will try not to give color commentary or opinions tonight, but a basic run down of the facts.
I pulled the bus in the shop about 7:15 AM.
I cranked it up about 9:55 PM to check for air leaks and then take a test drive. After looking for air leaks and inspecting things after the test drive I pulled into a spot for the night at 11:00 PM.
Here are the things that were completed in 15++ hours.
Replaced one R-14 valve.
Replaced one R-12 valve.
Replaced the wheel seal and brake pads on driver’s side tag.
Replaced the wheel seal and brake pads on passenger’s side tag.
The calipers are taken off anyway so there was essentially no extra labor to change the pads while the seal was being replaced.
Installed a new “thingamahoochie” that fastens the tag chain on the driver’s side.
Three different guys worked on it from three different shifts. No one mentioned any difficulties or problems along the way and I was nearby in the lounge or sitting on the outside bench the whole day. If there was any problems they gave me no indication.
Davy
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Hello Group,
I am chasing a leak which goes this way….while driving it seems like the prime,second and aux pressure stays up and pretty solid with the aux compressor off. If I have the aux compressor on while driving all gauges will slowly drop to 100lbs and then cycle back up to 125llbs, prime and seconday. While parked, with aux comp on it takes 60 min before the aux drops to appox 70lbs, and aux comp cycles and stops. If I leave the aux comp off the system holds air much longer before cycling.
Is there a check valve in the aux comp? I have found and fixed a leak up front where the 3 gauge 1/8″ lines feed from but overnight the prime and secondary gauges still slowly bleed down, and turning on the aux comp does not raise prime and seconday gauge pressure.
When aux comp is running there is a musical noise like air flow noticable back by the bathroom/bedroom area.
Is this going to be the R-12, 14 valves also?
Thanks for all the great info you all provide.
Jonathan
1997 XL Royale #201
ps: how do I get my signature on my posts?
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Do you have a air toilet ? What does the aux compressor run can’t be much , I had a 1997 Royale after I was done with it it was leak free the only thing was the toilet that used air and I took it out and put in a tecma toilet gen air bags where manual fill I put a solenoid in for the seat only air to it when key was on and shut off valve for step slide the door air lock can also leak air out the bimba valve
Try not to mix up the systems first work on the primary or back gauge going down then the secondary or front gauge then you can work on the aux gauge or aux compressor ,you can start on any one of them you do not have to do them in the order that I said expect the front and back gauges or primary or secondary gauges they are the brake systems ,if both the primary and secondary are going down together look at the park brake valve it will drain both down at same time
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Click ‘Profile’ at the top-right of the screen and fill it in. I found that a picture will not show unless it is accompanied by text.
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Jonathon,
You do not need the aux compressor while driving. The engine driven compressor likely puts out greater pressure so the aux compressor probably isn’t doing anything.
Keep in mind that you should have a check valve of some type to keep aux air leaking back through the compressor to atmosphere, but also between the aux system and the braking system. From the post I suspect you have never checked, or had someone check to verify the operation of the air system check and protection valves between tanks. This should be done routinely by someone who knows what they are looking for.
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Finished at Prevost Ft Worth today. Had to replace one R14 valve. The connections at the valves were leaking, but the hoses going to the brake valves were also leaking. While under the coach, found the end link bushings were bad, and the curb side tag axle seal was leaking. Now we have a happy coach again–at least until the next issue. Sitting at Marathon today, took care of some lighting issues, and installed bay door bumpers I picked up at Prevost–had six bad ones. Also tightened up bay strut connections–some were ready to shuck the strut. Heading west tomorrow to crash the Newell rally at Ruidoso Motorcoach Ranch!
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While you had access to the underside did you check your air tanks for moisture and verify the protection and check valve operation?
Just asking.
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Of course, Jon. I haven’t forgotten. Very little moisture out of the tanks. Had Prevost put a new cartridge in the air system in January.
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