Hey guys,
I've been trying to troubleshoot an air leak in the bus that just materialized suddenly.
A bit of background:
We've been parked here for about a month or so.
To maintain level, we've been using the bus' automatic leveling system.
To keep the air bags full I have an electric compressor hooked into the main air tank.
That has worked pretty well for us so far and the compressor comes on once or twice a day to keep the bags at about 110 psi.
Anyway, sometime today we were just sitting in the bus when I could hear a hiss from outside, towards the back of the bus. There was no pop or any sudden release of air, just a pronounced and steady hiss.
I went outside to look and it sounded like it's coming just forward of the rear wheels, in the middle, and if I had to guess it was on louder passenger side.
I checked to make sure the tank in that general area wasn't somehow open and I poked around in there as much as I could comfortably manage but I could not find it.
The leak is enough to remove pressure entirely from the lines. As where it had been a steady 110, it's now at or near 0.
Thinking it might be the leveling valves getting stuck, I tried to rock the bus back and forth to see if that would unstick them (maybe not something one does, but all I could come up with, lol). Anyway, that obviously had no effect.
Then I got to looking at the book and if I'm reading the air diagram right, the air bag system (including the valves) is a "separate" branch unto itself within the whole air system. The bags are still full and holding the bus nice and level. So I don't suspect a leak in the bags or the suspension system.
After draining all the tanks with what little air was left, I turned the compressor back on. The leak was still there, but I used what little pressure it had managed to build up to pump the brakes a couple of times. I could hear the front brakes actuating.
That also appears to have had no effect.
Any advice on where to look?
It just popped suddenly. We weren't moving and had not moved in a while.
I've been draining the air tank maybe once a week or two and there wasn't a whole lot of moisture in them.
I'm going to continue dissecting the book a bit, but I'm not even sure what system to start looking at. I don't have a way to block the bus, yet, and I'm hesitant to crawl under it, especially with an air leak in the mix. The bags are holding fine right now, but that will not last long.
Anyway, as always any help is greatly appreciated.
Thanks
George
Don't know about your GM but on my MCI that sounds like it might be the rear brake relay valve.
I'd guess (I don't know anything about your particular bus) that the first place to start is to locate the source of the noise. Usually a leak happens right where the noise is (like a hole rubbed in an air line) but sometimes the location will tell you something else (if the leak is diffuse and coming from a quick-release valve, look at the place that that valve controls -- i.e. if it's a quick release for the rear brakes, look for a leak in a brake canister assembly).
Also, the source of the noise will point you towards the possible issue. Do you have an air dryer and does that air dryer work in line with air from an external compressor? Since you've been using the air suspension mostly lately, it is likely that will be where you find the problem but you can never be sure until you do the detailed work.
A 4-foot piece of small stiff hose (I use 1/4" DOT line) and a spray bottle with bubble soap in it are your best friends at this stage. But be careful of the suspension doing things you might not expect it to do (like moving when it shouldn't) -- use GREAT CAUTION if you have to get under it.
When that exact same thing happened to my bus (MCI) it was the 85 psi pressure regulator for the DD3 parking brake control. Just a little square valve mounted on the front wall of the axle bay.
Brian
Had a very similar sounding leak on my 4501 and it was the front air leveling valve. It was an original bendix unit and the air was leaking from the seal around the shaft to the actuating arm. Moving the bus had no effect because the seal leaked no mater what position the arm was in. The bags could be full or empty and the air flow was always the same, a small his under the front of the bus.
But he said it was at the back of the bus, not at the front.
Hey guys, thanks all for the replies and things to look for. At first I suspected the rear relay value since it's in roughly the spot the sound was coming from.
Anyway, I finally 'nutted up' and got underneath the bus. I used some of the stackable rv leveling blocks we had and stacked them under the engine cradle front mount. Not exactly perfect, but good enough.
Armed with my spray bottle of soapy water I proceeded to hose everything down that I could, to figure it out. After some random spraying that accomplished nothing, and after developing more confidence (or is it stupidity? I don't know the line is so vague :)) I crawled further under there.
It became abundantly obvious, no spray bottle needed, lol.
One of the brake lines had a pretty significant slit in it. It's (one of) the line that runs from the passenger side dd3 to the reversing valve. I think it's the "Parking and Emergency port". It actually looks like there's a seam that runs the full length of that air line. The leak is in a split along that seam.
I tried a little bit of 'George Engineering' to see if I could get it sealed enough to get it to a diesel shop (long shot I know, but 'George Engineering' has occasionally worked in the past so I figured WTH. I wrapped the line up in some heavy duty pipe tape (fancy duct tape basically) and <shock> it didn't work, lol! It worked for a bit, but considering the pressures that line is under it's not too surprising my little rigging job didn't hold.
So now I'm kinda stuck. The bus won't hold pressure to make it drivable and I'm not sure I'd drive it in its present condition. So I can't get it anywhere to have it worked on.
But after spending some time staring at it (I've gotten entirely too comfortable being under the bus at this point) it occurred to me that i could actually replace this line, if I have the hose made with the ends on it. It just looks like a neatly threaded connection that I should be able to remove from the dd3 and the reversing valve side, and install the new replacement line.
The question is, now, where or how do I get that line made? Is that something that's a standard issue part that can be bought somewhere? Is that something that has to be made? Is our good friend Luke able to provide me with such a thing?
Any other advice?
Thanks again in advance,
George
Napa store, any hose shop...While your there get some hose and ferrels unions...one goes others may be close behind....
Quote from: eagle19952 on September 30, 2014, 03:38:48 PM
Napa store, any hose shop...While your there get some hose and ferrels unions...one goes others may be close behind....
Will the replacement hose come with ends? Or are the ends user replaceable? Or will napa install the ends? Do I remove the hose and take it to them?
Sorry, have not dealt with this before.
There's not a napa close, but there is an orielly. Would they be able to handle it?
Quote from: Geom on September 30, 2014, 04:03:27 PMWill the replacement hose come with ends? Or are the ends user replaceable? Or will napa install the ends? Do I remove the hose and take it to them?
Sorry, have not dealt with this before. There's not a napa close, but there is an orielly. Would they be able to handle it?
There are a couple of places near me that have pre-made
hoses; and by that I mean
hoses which are rubber and have the woven fabric reinforcement. This is different from the nylon-like DOT tube which is a solid plastic - no woven fabric. Hoses connect a component on an axle to a stationary item like a valve on the chassis. These hoses are in a rack - you can choose from 12" - 14" - 16" - 18" - 24" - 36" etc. They are "fully made up" - they have one end that's a solid thread fitting and the other is a slipping or swivel fitting so that you can screw the thread into a component. You buy them for $14 - $18 (or more for the longer ones) and it takes 5 minutes to install one.
But there's a trick that you should put in your "George Engineering" tool bag. If you have a small hole or split in an air hose or similar (like a water hose), you can sometimes limp to help by putting on your heavy-duty tape on and them compressing the whole thing with a handful of screw-type hose clamps. Often if it splits or tears, it will just split or tear somewhere else but - if you're stuck - it's worth a try. Also, if you have a crack in a hose or pipe near a metal fitting, you can sometime cut the tip off the hose or pipe and get it to connect back into the fitting; obviously, there has to be a little free play for this to work. And the same applies, if it's in bad enough shape to crack or split somewhere, it's probably going to crack or split somewhere else soon so be sure to do a good repair ASAP.
Just remove the hose, take it to a truck parts store and ask for a new one. they will either have a ready made one, or will make you one, or will sell you the hose and the ends and you will make it - it just depends on the size and the ends. Once you get that hose fixed you get to replace all the hoses back there - been there, done that. The hoses usually come with one fixed end, and one end that can be "clocked" so that you can tighten it up with with the other end fixed tight.
Brian
Yeah, Brian and I contemporaneously posted. We're talking about the same thing.
Most of the time from the rear relay to the can the hose has reusable nuts with ferrels guess we will see when you remove the hose is so all you need is the length of hose and 2 new ferrels
In order to move the scenicruiser home I had to re-plumb all of the rear brake lines to the tag axle. The modern DOT air lines are plastic. I chose to use Synflex tube from Eaton. I expect to do a lot of reworking of my air system so I acutally bought rolls of tubing in different sizes. The brake tubing I used was 1/2 inch. Part of the system was already compression fittings with the compression nuts and compression ferrels. If you don't know what that is, it is the same kind of system used on most supply lines to ice makers in refrigerators. you slip a threaded nut onto the tubing, then slip the ferrel which looks like a little brass doughnut and you stick the tubing into the fitting on the brake canister and then slide the nut and ferrel down and tighten them together. The other system that I have seen is more like the connection for a natural gas line on your appliances. there is a flare on the pipe that is squeezed against a matching contour on the fitting. The compression is really easy to do yourself. The flare usually requires more specialized tools and seems to be less common so may be harder to get parts while out on the road. Compression fittings are sold at hardware stores, auto parts stores, and truck repair centers. Flare fittings are also sold in similar spots, but the flare ends on the hoses may have to be made by a place with the flare tools.
George, You might be by another busnut that can help if we knew where you are close to.
Also any Parker hose and hydraulics stores around or ask at O Reilly's if any Hydraulic stores or shops around. Camping Worlds, Truck shops.
Also when you get home get Coachnet 129.00 a year is worth it.
Dave
if your close to an o'riley as mentioned try telling them this number 27266 gates for reference to a new style of air brake hose that is used a lot and is a dot hose. But removing the complete hose is great, if nothing else cut it in half and take what you can as the guys mentioned most hoses that are a braid have field serviceable end fittings so just the hose can be replaced most of the time. I will say most hoses on the buses are of a super duty.
hth
Thanks everyone for the great info provided! I feel much better about the state of things now :)
From the sounds of it, I think I need to get back under there tomorrow and pull that line. That'll give me a better idea of what I'm dealing with and what kind of ends it has and whether they are reusable.
I also completely agree that I pretty much want to replace all of those hoses back there and I'll make sure to keep some extra hoses on hand for the future.
I'll also make sure to look for actual hoses vs those plastic tubes mentioned.
Thor, thanks for the detailed explanation of the fittings. I guess I'll find out what I have in a bit but it's great knowing what's available. Can I use compression fittings if the original was flare? Or is that also matched on the equipment side?
Bruce, thanks for the added good "engineering" tip. I'll definitely keep that in mind as I have several of those hose clamp things around!
Dave, we're in Mountain View, MO a little bitty town about an hour and half east of Springfield.
We actually do have coachnet already and I completely agree that it's well worth the cost. It's my failsafe plan if I can't get it done on my own. I'd just rather avoid being towed out of here if I can at all avoid it. :)
I did have a couple of questions
1) is there an easy way to identify which end on the hose will free rotate so I can remove it first? Or is trial and error?
2) when putting the new hoses back on, should I use any Teflon tape like I would on a water fitting?
Thanks again!
George
George look for the two nuts together with a small gap between them. You can use two wrenches and one will turn out and then the other will turn out of the valve etc. Some are trial and error.
Yes Teflon tape or liquid just make sure there is none that gets in the fitting. doesn't take much to stop up a valve.
Good Luck and let us all know how your doing.
I think (Scott) is in MO somewhere. harleyman_1000@yahoo.com
Dave5Cs
George I wished I was closer than 150 miles, but you mentioned your location in Mountain View there is an auto parts, that can deliver to some extent parts.
CARQUEST ph 417 934 6594, I have talked to the fella he makes up dot brake hose in store and also has some premade his store is west of town His name is Dale.
I ask him about a truck service also and he mentioned Gentleman Jims in town 417 934 6594.
good luck and good day
Great, thanks Dave. I'll post back with more status after I get that pulled this week. The weather is looking kind of dicey today and I may wait another day to get back under there.
I guess if it does rain, I'll have the "shelter" of a 15 ton bus above me, lol!
Brmax, thanks a lot for the info provided! I really appreciate it. I'll give Dale a call.
Someone else around here (RV park) had mentioned Gentleman Jims in passing so I may be giving him a call as well. We'll see :)
Thanks again!
George
Here is a pic of a re-usable or field serviceable air line fitting
http://www.brassfittings.com/images/reusableairbrakeftgs-pic.gif (http://www.brassfittings.com/images/reusableairbrakeftgs-pic.gif)
Bottom center, in it you will see a castlated sleeve you would need to buy.
Also RH center is some nylon (or Synflex) air line fittings.
And here is a picture of a ready made line. You will notice one end is more "complex". That is the swivel end as indicated.
http://www.thetruckersreport.com/truckingindustryforum/attachments/trucks-eighteen-wheelers-/39509d1354471407-looking-air-chamber-hose-595959-jpg.att (http://www.thetruckersreport.com/truckingindustryforum/attachments/trucks-eighteen-wheelers-/39509d1354471407-looking-air-chamber-hose-595959-jpg.att)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.brassfittings.com%2Fimages%2Freusableairbrakeftgs-pic.gif&hash=8db53e51a85bb4cd36e61ecafe015af067971313)
http://www.brassfittings.com/reusableairbrakeftgs.php (http://www.brassfittings.com/reusableairbrakeftgs.php)
Hello all,
It's been a while and I wanted to post an update on this.
The weather has been nonstop rain for days and I've been chasing water leaks instead of air leaks the last couple of day, lol. I have a couple of leaky windows that I've been battling for a while and every time I think I've won, a new front in the battle emerges :)
Anyway, we finally had a nice sunny day today, so I managed to get enough pressure built up in the system to raise the chassis and block it. I got under the bus and proceeded to remove the bad hose. After screwing with trying to gently remove the hose from its present position, it became clear that I would not be able to do so, without the hose tearing. Neither side of the fittings was a swivel connection. So turning one side tightened the other and so on. So I decided "screw it" and continued turning the hose. It eventually gave out by fraying and splitting completely (it definitely needed to go!). So I'm not sure what kind of hose-installing-jujitsu it took to get it on the first time, but I couldn't figure it out.
Anyway, I took the hose (bits) to carquest, they were able to easily cut another shiny new hose, and I asked them to put swivel fittings on there. So whoever replaces these hoses after me should have a much easier time, lol! After I got it installed and did a pressure test, then a happy dance once I saw 120psi build up and no leaks; I decided to push forward and replace any other hose under there that I didn't like the look of. I already knew the driver-side dd3 "emergency port" hose had to go. I also saw that the hose coming from the rear valve to the dd3 was kinked and cracked, so off it went as well. That one made me much more nervous because the ends on it looked completely different. Anyway, back to carquest I went and he was able to make me a new hose for both. Although the one from the rear valve had some strain relief springs on it that were attached to the hose. He was not able to recreate that, but neither of us thought it should be an issue. I got it installed with a minimal bend radius and it doesn't look kinked or strained. The ends look different, but they fit in the spot they used to.
I did a complete pressure/leak test and everything looked good. I pumped the brakes a couple of times and could hear them actuating and discharging (while I watched underneath). I have not driven it yet, but I'm hoping that should be a nonissue since everything else looked ok.
So this is my long-winded way of saying thank you to everyone for your help, advice, and suggestions! I realize it's a silly simple fix for most folks on this forum, but I felt good getting that done, lol! And your help was crucial in getting that done! And now I know just a little bit more about how all of this works, which is always a good thing :)
George