Chasing Air Leaks

[Joe Cannarozzi]

Took about a good shot of dishwasher soap and mixed it ito a full squirt bottle of Windex and it makes a very foamy and sticky mix, check it out. It worked real good. Takes a few minutes for the soap to disolve into the windex.

I'm guessin.

I think I have air leaking by the 1-way checkvalve in line inbetween the compresser and that first tank. I can see it and easily remove it, its on the top tank. I don't know where else to look:mad:

I run the bus till the air dryer goes off 120lbs and shut it off, brakes set, and with no audible noise anywhere and every fitting, every valve, and every air bag top and bottom completly soaped up, find ZIP, zero leakage, and can't hear a thing while my air drops 1lb per min. I have scowered the thing today and I've already been in there a few times before looking. That is a big loss and should be noticable. How would you like to be paying some dummy like me to try to find a problem like this!

I can not be a happy camper till I figure this out:p

I know mabye the engine air compressor but not real common. Not the parking brake valve or tag dump switch either, both replaced last year and soap tested, more than once.

I say checkvalve first It doesn't cost much. Any suggestions?

I have found a wiper control just barly bubbling. I also just put in a low air warning light sender that is in the steering bay. That was bubbling, and also found 1 loose fitting in there. Wiper control will wait till Monday, its not the problem, something way worse than that.

[Jon Wehrenberg]

Joe,

You have a leak that is big enough to hear.

First, if your bus has the emergency brakes "on" your entire braking system has zero air pressure applied so you don't need to look there.

If you can get your coach inside there is a possibility you may hear the leak. Unless I have a leak inside the steer compartment or in the engine area it is difficult for me to hear or pinpoint the leak when the coach is outside. But if you cannot see it with soap bubbles under the coach, try listening with a stethoscope. They are cheap and if you first use the funnel it will let you pinpoint the area, and then the narrow tube to isolate the leak. If that does not work then see if you can get or borrow an ultrasonic leak detector.

I concur with your idea about the check valve. It sounds reasonable and a stethoscope should hear the internal air flow to save buying one if not needed.

Since you do not have a typical conversion, there may be areas on your coach that are unique to your coach. On our conversions there is no end of potential leaks such as sliding floor, pocket doors, bed lifts, air lock, belt tensioners, air horns, etc. None of those are going to be detected from beneath the coach.

[Joe Cannarozzi]

The only camper pnewmatic stuff in the bus is the pass. floor and air door lock, both sealed up tight. Oops, lets not forget the Dave Mathews switch.

[rfoster]

Joe: I searched and searched on my coach, replaced air bags (one pin hole leak), and even after replacing air bags couldn't find the culprit. I was leaking down to zip in 4 to 6 hours. Will the assistance of A1s ultrasonic leak detector, in less than a minute we heard/found the leak in the front steering compartment in the Norgren Valves (two) that did not bubble or have audible sound. Apparently the air was following a hidden escape route thru the valves and only was found thru the amplified sound that only Superman could have heard with the use of an ultrasonic leakdetector. So two New Norgren valves later it is cured.
Much aggravation and time invested but I know what to do next time.
Luck to you without the use of a detector. :cool:

[jello_jeep]

Joe,

I was leaking pretty good too, and found a fairly major leak in the little regulator for the belt tensioning bags in the engine bay. Follow the air line from the bag, you will find the little regulator mounted above the engine bay doors ( you have to stick your head inside and turn around to see it ).

Not sure if your make/model year would have one in the same place, but its worth a look.

I think Tom was the one who told me about that one. And he was right!

[Jon Wehrenberg]

Joe has OTR air, and because of that he has the pneumatic belt tensioners and the regulator that JJ mentions.

At the rate Joe is leaking he could open the rear doors and hear it.

I believe that is aux air, so it is unlikely a leak there will pull what sounds like his primary system down.

[truk4u]

Joe,

Soap up the fittings on the step slide and regulator real good, the step slide on mine was a b...... to get to. I'll bet it's those freaking Norgy valves. Also, use kids bubble soap, it really shows the leaks.;) We're pullin for ya......

[Just Plain Jeff]

Joe: Pretty tough to diagnose online here.

But here's a personal experience if it helps. (Previous coach).

We were tooling down I-81 to a long downgrade near Hillsville, VA (where something always seems to go wrong) and air pressure was dropping rapidly.

Pulled off quickly and just as we got into a parking spot, the bus sat down flat. As in zero air.

So, put the external air supply to the coach at 110 psi and sat and listened. The air was coming out of the curbside tag brake chamber, I believe it is a Number 50, as I recall. The brake chamber had toasted, as the diaphram was hissing like the mother-in-law who hated you from the moment you took her daughter away.

Since I don't know anything about all the mechanical stuff or how anything works, took a Vise-Grip to the input air line to the chamber and wire-wrapped it up tight to some of the other stuff under there. Started the engine, the bus came up, the air held and we drove it to Florida to have it replaced by people who actually knew what they were doing.

Yes, I am aware that this was a Non-POG-Approved-Stupid-But-It-Worked (NPASBIW) repair.

A guy wouldn't normally figure that one of those dealies would go out while going down the road, but it did.

Oh, despite the NPASBIW repair job, still have the Vise-Grips and am saving the used wire ties for Jon because he likes to keep a supply of extra parts on hand to fiddle with when he is bored.

Now if I could just remember to give the ties to him...but that's CRS, not NPASBIW. Wait, since Mango Bus Lines are PP's, maybe he should get the ties? Hmmmm.

Good luck to you!

[Joe Cannarozzi]

Jeff

Thats a weird one.

That chamber on the tag on ours is not a maxi but rather just a service diaphram. When you reliese your parking brakes, no air goes to it, it is just a service chamber.

The only time air is going through that line and to it on ours is when you are braking.

Did they put Maxis on the tag axles on some years?

If you found it by airing the bus up and it leaked just sitting there then there must have been a maxi on the tag.

Just a tip-Sometimes when a maxi brake chamber starts leaking emergency air it is a little tricky to figure because often times when this happens the brakes on the opposite side of that axle will drag harder. I think this occures because as the air tries to couninue to the other side past the leak it gets even less volume there. Hope that didn't confuse. Also sometimes when a maxi starts leaking it leaks at the valve feeding it not the chamber itself. Sometimes it might feed air back through the emergency brake button too.

Jeff It is preferable to eliminate a leak by whatever means and come in with 1 less hub braking that to not. Vice grips, zip ties. I have heard if you take the line loose from the fitting and put a dime in the end of the hose and put it back on the fitting it makes a perfect seal. Duct tape and tarp straps. That would be a good name for an old bus.

It is my opinion the obvious and next best thing to do if a repair is not possible.

Truk Our step stuff is in the pass. arm rest attatched to the wall, not bad at all to get at. The step has a adjustable regulator on it that if I turn all the way up kicks that step out so fast it could decapitate a small dog.

Just an observation:rolleyes:

[MangoMike]

Joe,

One of the guys at POG II had a good idea about finding leaks.

He started disconnecting air lines fromt the AUX manifold until he isolated the source of his leak. If this doesn't detect it, at least you know it's not in the AUX system.

Mike

[Just Plain Jeff]

Joe:

I may be dead wrong on this; but here it is anyway.

The dealie that I disconnected on the 93 chassis was for activating the tag axle lift, or so I was told.

But you can tell a guy who doesn't know anything just about anything if he will believe it.

[Joe Cannarozzi]

Ya I know LOL It's all good.

Henry Ford was illiterate, you know how his courtcase story goes.

We all have eachother :)

I been working around heavy equip and trucks my whole life and can't find a, on a scale of 1 to 10, 1lb per min leak on the bus that I would concider a 5 or 6? Not good, almost embarising.

Yesterday I think I actually was able to give some helpful computer tips to Jon with his pics.? UNBELEAVABLE How did that happen :confused:

[Joe Cannarozzi]

Debbie has taken the grand-kids to Tenn. and has been gone since Friday morn, in case anyone hasen't noticed.:o But it has afforded me the opportunity of some personal time with my bus:rolleyes:

The weather here played right into my hands cause looking for air leaks are more evident in colder temps. and its been in the 30s.

I have been messen with it for the better part of 2 days. As it turns out I have found plenty.

Very slow leaks at the wiper control, low air warning sensor, both of 2 small diaphram valves inside the tower above the left drive air bag, and the A/C belt tensioner shaft.

2 other loose fittings 1 in the steering bay and 1 on the engine, both slightly worse, and I have found constant air escaping at the exhaust port for the ride hight valve R-Rear that is where the lions share is going to. YeHa. Success. Much additional confidence of knowing I have thoroughly gone over that bus with the soapy squirt bottle front to back 3 times now too.

The other 2 height valves were both bad and replaced early on last year, now all 3 will be new. Can't wait for tomorrow morn. to get here so I can call Elgin:D

[Joe Cannarozzi]

I installed a new ride height valve and it has slowed my leaking from 1 lb. per minute down to 10 lb. per hour. Much better but still not good enough.

Waiting for the remaining valves and belt tension cyl. rebuild kit. If those items don't get the rest of it my newest best friend Orren:D has offered to UPS me his ultrasonic leak detector so I can find the small ones I can not hear.

Thank you again Orren.

[Joe Cannarozzi]

It was 12 hours ago since I built up air pressure and shut it off. We are down to 50 lbs now but for the first time in the year since we bought it the suspension is still up the morning after:)

Found some issues at the belt tensioner/regulator and corrisponding air lines.

I still know of 2 small diphram valves up in at the drive axle that are bubbling that came with yesterdays part order. Those should cut that remaining leak by at least half again, mabye more.

[win42]

Joe: Don't find them all, they may throw you out of the Chicago Low Riders Club.
Thanks for the detailed description as you went along. I'm still trying to find my leaks, but I'm gonna do it.

[Joe Cannarozzi]

I would have taken some pics. but Deb took the camera to Tenn. with her.

While replacing a small diaphram valve up in by the rear end yesterday (one of 2 that are bubbling) I have discovered that not all my air bags are new like I thought and the one at the R-R leveling valve has a pin-hole.

Prevo calls those valves relays, couldn't tell ya their exact function. Debbie is back with the camera and I'll post a picture of it later.

[Jon Wehrenberg]

Joe,

There is no way to tell the age of an air bag that is installed. When you need to know the age in the absence of service records it can be found on a paper sticker on the top of the air bag. If the paper sticker has been destroyed it is probably because the air bags are ancient.

On my coach and Roger's we could read almost every date and at the oldest they were 10 years old.

You are lucky to have found a pin hole. Often the failure is in the metal can on the bottom and leaks there (due to rust) are almost impossible to detect because of the outer part the air bag rolls over.

[Joe Cannarozzi]

The saga continues. It just took 26hrs. to go down to 25lbs and it looks like its holding there.

I ordered an air bag today but in an effort to check further before it arrives I have aired the bus up with the leveling system on and the back suspension all the way down. That is gonna help tell me if there is still other issues.

Even with the pinhole in an air bag I found yesterday it takes every bit of 3hrs. to go from 120 down to 100lbs. At this point it is actually safe by legal deffinition for a commercial vehicle.

Now it has become me verses the bus:eek:

The 2 air compressors are loving me for it:rolleyes:

[Jon Wehrenberg]

Joe, I don't know if this will encourage or discourage you. On my old coach it was around 10 years old at the time and I started chasing leaks. It seems like I would find one, and after correcting that another would show up.

So I spent about a month of evenings removing, rebuilding, and bench testing every single Norgren, I replaced the solenoid valve pack, I replaced all the air bags, and I replaced the ride height valves.

It was worth it because for the rest of the time I had the coach I never had the leans. I don't think it cost me more than $1000.

[dalej]

Just to add a bit, I was adjusting the brakes after I was done with the seal job. When I released the air in the brakes, took it off park brake. I heard a leak in the air line. It was the line that feeds the drive axle to keep the spring from setting the brake in case you loose air. It had to be leaking for a while, just can't hear it while you driving down the road.

I don't think I have ever checked for leaks with the park brake off.

Learned somthing else today.

[Joe Cannarozzi]

Dale

A 3 part process.

First you need to get the thing to hold air with parking brakes set.

When you get to that point then you can release the parking brakes and listen and watch the guages. This would be the emergency air leaks your now listening for.

Last but not least with the parking brake released and no leaks, step on the brake pedal and hold to listen for service air leaking.

The maxis on the drive axle have 2 lines going to them 1 is emergency air and the other is service air. The tag has only 1 line supplying it, service air only.

Chasing emergency leaks and service leaks are reletivly easy to find and fix. Getting the bus to hold air in general is the tough one. You can't really begin to check for emergency leaks(brakes released) until you first get the system tight enough to be able to tell that the loss of air, if any, with the parking brake released, is from an emergency source and not just a leak in general.

[Jon Wehrenberg]

For those of you with manual slack adjusters (and you know who you are!) if you are under the bus greasing it, why aren't you also adjusting your brakes each time?

If you were doing that you would have your emergency brake off every time, and would have early detection of a leak.

Now that I have preached....I have automatic slack adjusters and I do not release my emergency brake and look for leaks as often as I should.

[Joe Cannarozzi]

Heck Jon we have auto adjusters on our 86 how far back do you have to go?

[dalej]

He was talking to me, I should have known better. :(

[Jon Wehrenberg]

I think Joe has had his slack adjusters changed if he has automatics.

All I know is my 87 had manual adjustment. I don't know what year the automatic slack adjusters were first installed.

I have to be careful picking on Dale. I want a friend that can tell me how to get my wife to break down my wheels and polish them.

[BrianE]

Just before leaving home in February, in an effort to correct a slight right lean, I discovered a leaking 5 port Norgren in the right rear leveling position. When I replaced the valve the leans didn't get any better but the lure of the highway won out and off we went. Since then I have rolled around under the bus, in the dirt, :mad: and replaced both the primary air tank check valve and the rear brake quick release valve, both of which were leaking and neither of which were contributing to the leans. Enough was enough so we squared off the corner heading towards Kerrville and spent 3 days at Prevost in Fort Worth.

At first it was discouraging to see the "experts" going through the same soapy water trouble shooting routine that I had been exercising time after time with no results. I was dismayed to see they didn't use any kind of listening device, ultrasonic or otherwise. The Fort Worth folks told me they were not aware that ultrasonic leak detectors even existed! Prematurely, I then jumped to the conclusion that the decision not to use listening gear was an attempt to prolong the trouble shooting process. My first reaction to this assumption was to write a scathing commentary about these guys to my POG buddies. Luckily good sense prevailed and before getting out the poison pen I called Bill Jensen, Service Manager of the MH division who, after giving me a very informative air leak trouble shooting lesson, agreed to order an ultrasonic leak detector for the Fort Worth shop. In less than an hour David Jacoby, the Fort Worth Manager informed me he had an Amprobe (thanks Jon) ultrasonic detector on its way.

Bottom line of the whole experience however is that leaks were detected in two airbags using soapy water, leaks that I had completely missed. The leaks were found by guys that do it every day and unlike an amateur like me, know where and how to look. I also picked up a number of tips on finding leaks, such as raising the tags in order to eliminate them from the puzzle and that internal leaks in Norgren valves usually vent to the atmosphere if you know where to look.

In conclusion, I need to apologize to the Prevost folks for jumping to conclusions. I also need to thank them for only charging me for six hours labor when I know they spent over 10 hours on the problem. At $92.00 an hour its pretty easy for us to be critical of Prevost maintenance and to avoid them if possible. I for one, won't hesitate to use them in the future when I get in over my head. I'm only sorry that they don't have a northwest location.

[Jon Wehrenberg]

Brian has made some excellent points. Because of the huge number of potential places for leakage in our coaches there is no single way to find leaks. I hope Brian is willing to share in greater detail some of the techniques.

When I have to start chasing leaks I will first rely on my ears. I just get it as quiet as possible in the garage and air up the coach and its systems and start listening. If I think I hear something I use my stethoscope, first with the funnel on the end and then with the long probe.

I also use soapy solutions whenever I am in the area of a leak I can hear.

But not all leaks can be pinpointed using a stethoscope or soapy solutions. That is when the ultrasonic leak detector comes into play.

When we deal with leaks at POG III it will be easier to understand why some leaks are almost impossible to find. I have sympathy for the Prevost techs because I have screwed with leak detection on Liberty coaches for 17 years and I still do not understand exactly how the system works or how many places I need to look when the leak is making the coach lean a specific way. The Prevost techs deal with every different converter's systems and they often lack an understanding not only of the system, but the age or condition of the very components that are part of it.

[Just Plain Jeff]

Per Jon: -->I have sympathy for the Prevost techs<--

(Cue the Halleujiah Chorus!)

Anyway.

I've posted this somewhere before, or not, having senior CRS.

About six years ago we had an air failure while in Maine. Went to Prevost at St. Nicolas, company service facility.

They have made a rolling air-system diagnostic machine. It puts air into the bus, measures air resistance (lotsa dials) and a spider of hoses. They pull the original build plans from the coach by VIN as some vary. Then they have a protocol of Level-Low operations, engine on/engine off, etc. They nailed our air leak in about 15 minutes of checking. It was a valve in front of the D/N 50 box.

After watching that experience, and being aware that I had no clue what they were talking about, I have asked a number of other Prevost facilities about the device and they are unaware of it, and don't seem to be that interested in finding out.

This would be a good POG project. If Fast Roger is up for it, he and I will make one.

The one at St. Nicolas, of course, is made from stainless steel, rivets and no slide-outs.

Good stuff.

[Joe Cannarozzi]

Here are the air relays for the tag axle that I found bubbling at the flange for the diaphrams on them. Left hand, right hand, both the same valve.

1099

I'm sitting up inbetween the rear-end and the tag, looking at the drivers side. I believe that these regulate the air pressure for the tag air bags and it exhausts here when you dump it.

The new one is leaking, much less but at the same place.:mad: I tightened the phillips screws as much as I dare. I'll try to bench test the other new one first. The old one had loose flange screws too and Ill tighten them and bench test it too, might be able to seal it up. It would be a good addition to central spares.

1098

[Jon Wehrenberg]

Joe, I believe you have a different system than we do. I don't recall seeing those on either of my coaches.

[Joe Cannarozzi]

Parts came from Elgin.

[JIM CHALOUPKA]

Joe,
You could take the old and leaking relay apart and try to see why it was leaking and if there is anything you could do about it and it might further your understanding of how it works and why the new unit is leaking.
What exactly is the function of the Relay?
I would recommend tightening the mentioned screws evenly with a torque wrench or screwdriver only. Is a rebuild kit available or is this a cheap part that doesn't warrant rebuilding? Quite a while back you mention that your air tank had gallons of water in it and that the air dryer wasn't properly functioning. Now that you are working on the rest of the air system have you noticed any ill effects of that water in the system. Also in the same line have you found moisture further into the air system?
Are these air components returnable or are they like many electricals,(no returns)?
Just wondering
:cool: JIM

[Joe Cannarozzi]

Jim

Yes this is what moisture does. It's about 90 bucks. If not installed, returnable.
I am concidering slightly loostening the screws at the flange on the old one a little and then saturating the exposed edge of the diaphram with brake fluid with the intent of swelling the rubber enough to get it to seal up after retightening. If that fails I'll completly seperate it at the flange and reassemble with gasket sealer and try that.

May have to do it to the new ones they leak as well, mabye a little less than half as much, nice hu:eek:

[JIM CHALOUPKA]

Joe,
If you take the old unit apart check if the mating surfaces that come together and leak are flat and not warped or miss machined/made.
How does the relay function. What is it's function? Is there some sort of valving or pressure regulating devise in the cavity in the gasket area? Why is there such a large cavity covered by the leaking cap?
:confused: :eek: JIM