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Air leak on push to connect, plus suspension leaks
Hello. I am chasing air leaks on my 2001 Featherlite H3-45. I have the left rear leaning first (usually overnight) followed by right rear at a much slower rate. All bags were replaced about 3 years ago, by previous owner, not sure where it was done, but I bought this coach from Tradewinds, and they may have done that work (I think some work was done by Pantera coach as well). At the moment, I am chasing leaks by listening and/or spraying soapy water on connections. I have not pulled the rear fenders off currently, but I did that once before and sprayed all connections I could see but could not find anything.
In spite of not seeing problems with the spray method, I could easily hear a leak, which was coming from the right side, located front-to-rear between the tag and drive axles, way up there (nearly unreachable from under the bus). I could detect the general area it was coming from by just listening, and found the exact leak with a mechanic’s stethoscope. It appears to be leaking on a push-to-connect fitting. This is where three blue air lines join (3/8″ I think, not sure). There is 1 90 degree fitting and a tee fitting (these two joined by what looks like NPT). It is leaking on one of the push-to-connect for the tee. Of course it is in a place where I can barely reach from underneath, even if I manage to sit up on my creeper. I have managed to unbolt the fitting from the chassis, but now I am wondering what the best way to remove the air lines.
Should I just cut the air lines right at the fittings? Or do these push-to-connect typically have a way to release the tube (and even if they did, should I even bother with that?).
I assume it makes sense to replace both fittings. Where do you suggest I get these, Prevost? Once I take out the fittings, I’ll try to get a better picture of them, but I wanted to make sure just cutting the lines at the fitting was OK before I do that.
FWIW, I know this leak is probably not related to the bus leaning; it’s just another leak I have to fix. I do know it’s part of the Aux system, but once the bus is parked, I believe the airbags are isolated from the rest of the system, right? Anyway, this is the “squeakiest wheel” at the moment, so I might as well take care of this leak before figuring out the suspension leaks. With this Aux leak and an external compressor connected, it is cycling on every 20 mins or so, so I certainly want to fix this first.
Finally, I am curious if anyone would suggest removing drive or tag wheels to get better access to this (and for chasing the air suspension leaks) IMO, it’s going to be almost impossible to do this work from underneath with the current access. I might be able to swap out this fitting,. but I am wondering if I am just making it much harder for myself. I have the tools to remove the lug nuts (torque multiplier), but I have never actually done this before.
Thanks!
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21 Replies
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Hi Andrew, this is a complicated and touchy subject due to the high liability of a bus crushing you. I don’t flinch anymore when it comes to doing any work under the bus, I remove the wheels, as it makes life easier. You are going to need some heavy stands and a 20 ton air over hydraulic Jack to get the bus up in the air and supported these have been discussed all over this forum. The wheels are a different story. You will be able to remove them with a Torgue mulitplier, but putting them back on you will need a Torque wrench. I have had my bus wheels off many times and now it takes me about an hour and a half to put the bus up on stands and remove the wheel for the area i Am working on. Never go under the bus without support stands, and I recommend having someone assisting to make sure you don’t miss anything, preferably someone who has done this before. Once you get the bus up on stands and the wheels off you will have a much easier time to diagnose and work. Folks here recommend replacing the push to connect fittings with Compression fitting. To remove the push to connect you need to push the sleeve down and pull the hose out, might be easier said than done as the line gets stiff over the years.
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Fittings are available anywhere. You just need to select the configuration and the size and type of fittings (tube or pipe threads)
Push on fittings are a boon to manufacturers because of production time saved but as they age out they become and owner’s nightmare. Personally I have used almost all brands but the Swagelok fittings have been the best by far and now I use nothing else.
If you want to get beneath the coach make sure you block it under the chassis support points with solid blocking, jack stands or some other rigid support adequate for the work. With the coach raised all the way up you can slide into the areas between wheels which is where a great number of fittings are found.
Should you choose to let a shop repair or replace leaky fittings you may need a second mortgage on your home. It is time consuming, fussy, endless work and will still find you with leaks unless you have nothing better to do except chase leaks.
Good luck. We’ve all faced this problem.
With respect to leaks in the suspension and no apparent leaks despite an abundance of spraying soapy water there are two points to be aware of. First and foremost an air bag can have a serious leak you cannot detect unless you isolate the air bag, pressurize it and detect pressure loss. The way the air bags are made and supported a leak in the area of the bottom “can” will leak into the area hidden by the “piston”, the part the air bag rolls over as it is deflated. Air from the air bag or “can” leak can escape undetected where the plastic piston sits on the support plate or even through the holes in the support plate where the “can” is bolted.
The second point is an air bag leak that goes past the 5 port Norgren valve that is supposed to lock air in the bag with the key off can be found leaking from the three port valve in the steer compartment. That valve is where you will hear air escape when you manually lower the bus (or deflate the air bags.) That valve in the steer compartment is often overlooked.
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Thanks for all the tips. FWIW, while you were writing these replies, I lost patience and cut out the fittings (cut the hose with a razor right at the fitting to avoid deforming the rest if the tube), so now I have the fittings in my hands.
BTW I do have the bus on heavy duty truck jack stands on the rear, at the rear jack points behind the tag axle. I also have a 50-ton air-over hydraulic jack (complete overkill and honestly too big, should have gotten the 20-ton). I have jacked up the front and rear a few times, and more recently have come to like driving the rear on 2×12’s to get the coach higher, then raise the rear with level-low as high as it can go, then place the jack stands, then lower coach onto the jacks via level-low. I have done it without the 2×12’s and using the air-over jack, but I find it really hard to get a good spot to jack up the rear with the jack while not blocking the place where I want to place the jack stands.
Also, I should have stated, I do have other tools, including a torque wrench (1/2″), impact gun, and a digital torque-meter (3/4″ in/out, to 600-ft-lbs I think).
I was able to slightly better position myself under the coach and get a bit closer to the fitting location, but still not 100% I will try to put this back without removeing the wheels. I’ll probably give it a shot and proceed to wheel removal if it does not work out.
Thanks for all the advice on potential leaks. I will definitely take a look at the norgen valve up front.
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Whew! Sometimes folk ask these questions and have never done it. Sounds like you have the tools and the skill. Hopefully that line is long enough to use with the new fitting, if not you can replace it or add a coupler inline to extend the length. Do you have a source for fittings and Hose? If not, i use these guys, all various styles and sizes, DOT compliant and ship fast.
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Jon, when you used Swagelok fittings, did you need inserts, or is the DOT nylon type hose strong enough on its own?
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the feed(blue lines are suspension) at the alum coupler pictured. Sort of splices air suspension from supply to front. I use the ferrules. Go to prevostcar.com enter the last letter in your serial then last 4 digits=unit number..Puematic diagrams.Take diagram to office depot and have them blow it up as much as they cam. Also have them lamanite it. Example my 1998 coach is W-6553.
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Prevost Airline Colors
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I did not use inserts with Swageloks.
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I got the pneumatic diagram for my coach, or what should be for my coach, a 2000 H3-45 VIP, but the diagram does not show the bellow air tanks like some of the newer model year diagrams. Maybe that does not really matter. Anyway, based on the diagrams, it looks like the hose was leaking at the tee fitting that connects the passenger side height-control valve, driver-side height-control valve, and to something else up front. I am going to replace the 90 and the tee there with some swagloks, should be here in a couple days.
BTW, when the key is off, are the air bags closed off from the rest of the air lines via the 5-port norgens in the back?
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Andrew, on my bus when the key is off the air is trapped in the bags via the Norgren valves. Even if I drain my aux air to zero my bus will stay at Height.
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Your coach likely had the modification to correct the problem when accessory air pressure was lost.
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John, What inserts are you saying you don’t use? These?
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Andrew: play with that site PCar a little more and check coach specific changes by unit number. In the Articles listing on this site is a good general description of how systems(puematic) air systems work. The enlargement and lamenting cost me 10 dollars..I use dry erase markers to mark any changes made for system.Also for what it’s worth there were very little mods made to system for years. Under articles search prevost leveling system Bob
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Mike, yes.
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Why wouldn’t you use the insert? If you don’t use the insert there is nothing to keep the tube from pulling back out of the fitting.
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