Main > Pneumatic > Air leak repair Prevost Forum

old post - new post - new reply - closed threa

  2/20/2012 1:52:58 PM - Thread - tomhamrick  
Air leak repair

I am trying to chase air leaks and have found 3 so far that I can hear. The first one is what I assume to be the air filter for the suspension system. It is a Norgren filter F12-300-MD3A. The leak is coming from the threads that the drain cock screw into. Looks like plastic threads that have cracked. Can the threads be replaced? Is this part of a filter change? I do not want to mess with it too much until I get replacements parts so I don't cause a huge leak to put me on the side of the road. What is the best source of parts for this?  Prevost? Prevost part number for the entire filter housing is I believe to be 64-1135.

 

OK. Second leak is the Norgren ( I assume) electric operated valve for the camera pod door. the numbers that I think I see, reading it upside down is N71AA01-NSO-NDO. It is leaking out what looks to be the exhaust hole at the electric selonoid. The selonoid portion is loose and when I move it around the leak gets worse. Can this be repaired or replace the whole valve assembly. Prevost part for this is again I believe to be 64-1204.

 

Third leak is the left air guage in the dash. It is leaking out of the push connector on the back of the guage. I tried getting the 1/8" hose out of the coupler to no avail. Tried pushing in on the release and pushing and pulling on the hose but it just would not come out. I will next get a new push lock and replace it on the back of the guage and the should fix that one.

 

Thanks for the help!!



Tom Hamrick
Forest City, NC
1991 H3-40 VIP Hoffman Conversion
2010 Jeep Wrangler Rubicon
 
  2/20/2012 2:04:59 PM Jon  

Norgren has distributors in almost all large cities so if you have the Norgren part numbers the distributor in your local area can likely help you. Norgren is excellent for parts so if there are replacement parts or kits you can likely buy them through the distributor.

You really got my attention when you talked about fixing air leaks you can hear. Most of us wish it was that easy. As you get into your leak repair project  it is probable that on a coach that has not had regular leak maintenance work that you will have many hours dedicated to finding and then fixing leaks. As the leaks become less obvious the amount of time and patience required to find them increases.

The reward for having a leak free coach is significant. You will hardly ever have to run the auxiliary compressor, your bus will not drop unexpectedly when the aux system drops below 30 to 35 PSI and you will learn a lot about your coach.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  2/20/2012 3:09:49 PM tomhamrick  

Thanks Jon. I thought it best to start with the obvious. I agree it will take a lot of work to get it leak free, but I enjoy that type of investigative work. I am off to search for parts!!!!

Thanks, 


Tom Hamrick
Forest City, NC
1991 H3-40 VIP Hoffman Conversion
2010 Jeep Wrangler Rubicon
 
  2/20/2012 3:33:10 PM joelselman  

If that Norgren filter bowl is clear plastic, I've replaced 2!  They made a steel replacement for my application which I've now installed.


1999 XLV chassis X1026872, 2000 Liberty Elegant 440 Lake Havasu City, Az
 
  2/20/2012 5:54:55 PM Truk4u  

Tom,

Any chance you could post a few pictures of the items you need or what is causing your problems?

As for aux air leaks, it's a never ending battle, but worth the effort. I have been over every single valve, fitting or junction and still have a small leak somewhere, I suppose buried in the belly of the beast and not accessible.   Just getting the aux to a manageable level is rewarding. I use an electronic stethoscope that picks up small leaks even the soapy water doesn't show.




Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
  2/21/2012 4:58:40 AM TexasDrifters  

Third leak is the left air gauge in the dash. It is leaking out of the push connector on the back of the gauge. I tried getting the 1/8" hose out of the coupler to no avail. Tried pushing in on the release and pushing and pulling on the hose but it just would not come out. I will next get a new push lock and replace it on the back of the guage and the should fix that one.

....................................................................

My first adventure of chasing air leaks in my bus lead me to the same leak you are describing.  The fittings used to connect the 1/8" tubing to the Primary and Secondary pressure gauges are 'low hanging fruit" in the pursuit of managing bus air leaks.  The easiest thing to do is replace both of the the 1/8" fittings.  I searched for 1/8" compression fittings to no avail, so I replaced the fittings in kind with new push to fit fittings.  The new fittings rubber seals and the1/8" tubing worked fine.  I cut off an inch of the old 1/8" tubing to expose uncompressed tubing and reinstalled. 

I am the guy that had soo many leaks on my bus when purchased, I had to become very aggressive to manage these leaks.  I 1995 Prevost will sit for weeks and will not lean.  The aux air compressor will run every couple of weeks.  It will take effort to achieve this level of air tightness, but it is doable.

My last comment on leaks.  For me, leaks have been a moving target.  Meaning, getting a bus to a leak free status once does not mean it will stay leak free forever.  You will need to monitor and manage leaks.  Their are soo many opportunities for leaks in our complicated suspension systems.

Good Luck,

 

Hector



Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  2/21/2012 9:15:50 AM tomhamrick  

Thanks for the replies.  My filter is steel and not plastic but the threads at the bottom are plastic.
I will try to post pictures when I get a few moments, and that should help someone identify the part I need.
I am looking for new push in fitting for the guages, just have not found them yet.

Thanks,


Tom Hamrick
Forest City, NC
1991 H3-40 VIP Hoffman Conversion
2010 Jeep Wrangler Rubicon
 
  3/5/2012 6:59:47 AM tomhamrick  

Replaced the Norgren air filter Saturday and that stopped that leak. Was going to replace the Norgren in the engine bay that controls the rear view camera door, but it is so different and I am going to need more parts. It is the same function as the existing but is bigger, mounts different and the air ports are flipped in relation to the electric plug.

Also replaced the fitting on the left dash guage and stopped that leak.

I also have a couple of Norgrens that leak out what I believe to be the exhaust port (has the red plastic screw with slots on the side in it).  Can this be repaired with an O ring or does it have to be replaced?

Thanks again!!!


Tom Hamrick
Forest City, NC
1991 H3-40 VIP Hoffman Conversion
2010 Jeep Wrangler Rubicon
 
  3/5/2012 10:32:05 AM JIM  

Leaking out of a Norgren exhaust port, may mean there is a leak in some component up stream from that port, or it could be an intermal leak in that valve.

The rubber seals on the valve spools appear to be conventional O-rings but are infact special proprietaryy washers.  These washers can develop nicks and cuts that will cause leaks.

Note the roughness of the third rubber from the left, it is too rough to seal.

This is the shape of the rubber in the groove.  Note the nick that surely did cause a leak.


My recommendation; if you suspect the valve at fault, replace it with a new one, you will then be good for about 10 years.  Your job will be done and you can enjoy the coach.  Save the old valve and at your leisure take it apart and study the parts and pieces with a magnifying glass to satisfy your curiosity and understanding.  If you discover that the valve is not too corroded and looks reusable, grease it up and reassemble it for a spare.

Some internal parts are available from Norgren.  If as is often true the small screws break you can use all the other good parts for spares, but not the body with the broken screw. 

JIM



 
  3/5/2012 12:56:25 PM Jon  

At another time in my life I used to rebuild my Norgren valves thanks to the excellent availability of repair parts or kits from Norgren. It was a great learning experience but the bottom line was that I had to recognize two things. If the valve failed because of corrosion internally due to moisture getting into the system, the valve body was scrap. It made more sense at that point to buy a new valve. My last replacements were new, but the valves I removed were shown to be corrosion free so when the time comes to replace my current valves I will rebuild the old set. Jim has nailed it about the end cap screws and I find a very sharp rap on the screws with an impact tool plus soaking in penetrating oil helps the binding of screws that comes about because steel screws in an aluminum body is a sure prescription for corrosion.

The second thing I learned is if the object of repairing or replacing valves is leak free operation then regardless of whether rebuilding or buying prior to installation I do a quick bench test to insure the valve is leak free. I ended up making a simple rig with parts from Lowes to insure there were no leaks because after installation trying to find a valve leak is very difficult. They can leak internally past the seal, or they can leak sideways out the end caps. The leaks are very difficult to isolate when they are part of the air system on the bus.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  3/7/2012 9:31:52 AM tomhamrick  

Hey Tom,

Tell me more about the electronic stethscope. How much? Where?

Thanks,


Tom Hamrick
Forest City, NC
1991 H3-40 VIP Hoffman Conversion
2010 Jeep Wrangler Rubicon
 
  3/7/2012 11:18:39 AM Jon  

Tom H.....as you will figure out we all love encouraging other Prevost owners to spend money. Certainly chasing leaks is a fine way to get to spend a lot of money.

The use of your ears and soapy water is about as cheap as it gets for leak detection. I don't know if an electronic stethoscope is so much better than a $5 one from Sears but consider how much use you will get out of one. To take leak detection to the next level you need an untrasonic leak detector which will find leaks ears, soapy water and a stethoscope will not find but you will spend over $400 for one. The ultimate, but probably with a cost of less than $100 is to build one of Hector's bubblers.

If you build a bubbler however plan on spending hours, days and weeks opening up fittings connecting the bubbler and checking it for leaks, and if any are found, moving it downstream until you have isolated and repaired the leak. Sounds easy and it is, but it takes a lot of time and effort.

Or you can take out a mortgage and ask a technician to find and repair all your air leaks. In about a month you get your coach back and maybe there will be no leaks.

Hector......advice?


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  3/9/2012 6:42:02 AM tomhamrick  

WooHoo!!!! After doing the work this past weekend the bus still has 110 pounds showing on the both guages and has not been started since Sunday!! Now if I can get the Aux system to stay up that long I will be in good shape!


Tom Hamrick
Forest City, NC
1991 H3-40 VIP Hoffman Conversion
2010 Jeep Wrangler Rubicon
 
  3/9/2012 7:13:30 AM Jon  

As Hector has pointed out creating a "leak free" coach is a monumental effort, but once attained maintaining the coach in that condition is easy compared to getting it to that condition. On your coach the rewards for getting to that point are significant because as your aux pressure drops below 30 to 35 PSI I suspect your tag axle air bag air is dumped causing the coach to settle in the rear. The ability to maintain aux system pressure for your situation is highly beneficial.

Your first step is to learn the system and to methodically check each air circuit to see where the leaks are, and then to find and repair them. I get tired just thinking about that.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  3/9/2012 3:49:05 PM Truk4u  

Tom,

Your making good progress, keep at it. Aux leaks are frustrating and seem to be never ending. The only guy I know without an aux leak is Hector and by the time he reads this, he may have a new one. Hope not....



Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
  8/19/2012 10:03:54 PM repoer  

Did you ever consider putting freon in air systems and usuing a freon sniffer ?  to sniff out the leak


David
1993/94 XL Vantare 8V92
DeLeon Springs , Fl.
 
  8/20/2012 5:01:11 AM Jon  

It has been suggested as a last resort, but everyone should recognize it should come from a supply that does not contain refrigerant oils that may not be compatible with the various gaskets and seals.

The four common leak detection methods are listen with your ears, listen with a stethoscope, use soapy liquid to look for bubbles, or use an ultrasonic leak detector. The less common but 100% effective is Hector's Texas Bubbler which can test any system, circuit or device and spot leaks that are so small you can see the leak one bubble at a time.

There is no silver bullet and it takes a huge amount of time and patience. Once a coach is leak free maintianing that condition is easier than getting there.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  9/26/2012 6:08:07 PM Boateral  
air leak repair

 Look what showed up with soapy water... 

At the bus barn today in generator bay.  Just doing pre-trip inspection finding the pressure gauge read out on zero. Looking at the generator mini air bags no problem there.

Did a tap with my finger and pointer pops up  24 psi.  I track down the  mist sprayer and  here is what showed up. 



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  9/27/2012 10:04:20 AM BrianE  

Do something nice for Tom and he's likely to fix you up with one of these:

Steelmantools



Brian & Beverly
99Royale,'05Tahoe
Battle Ground, WA
 
  11/20/2012 9:21:19 PM Boateral  
air leak repair

The valve above is a SMC manifold air distribution from the main feeder 3/8 inch line located in the rear of my bus. The 5 ports  1/4 inch then feed Marathon dialed psi regulators aux systems  such as toilet, air doors, etc. When hit with the ultrasonic leak detector the reading was full max. positive air leak from the spaces in-between the double ports. It was a mini bubble machine with soapy water. The part was not available from my Eagle air parts supply here in KC. Eagle is a  fluid component parts supply and custom mfg. order. 

 Very busy shop running two  8 Hr shifts 5 days a week. Brian, on the air side of Eagle disassembled the valve installed new o-rings. The double ports seems to be a good part adjustable when it's building the bus. As time, heat, shake  take their toll...not so good.  A test with new Orings cured  the leaks. With the remounting in the bus and charged the system we had some minor leakage. 

Heat is the enemy for this part shrinking the O-rings over time

 Brian located a 5 port manifold this afternoon which as you can see below completely eliminates the above shaft leaking problem.  Mounting holes pre-drilled straight out or side mount. 

For other Marathon owners you can check in your rear closet behind either a pull down panel or remove a drawer underneath  your audio-video sets. If you have the plastic SMC manifold leaking  give me a call for this repair/replacement  part.

 Manifold and fittings $24. for a permanent repair.

 


 




2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  11/21/2012 5:36:43 AM Jon  

This is just a personal observation that I am sure our leak detector guru Hector will echo.

Our coach fittings have slowly but surely changed over years from compression type to the push in type fittings. There is no doubt push in fittings are very easy to use and start out very reliable. A lot of the fittings on my coach are push in type that are swivel 90 degree fittings as Al shows and they are in a gang on a manifold. But as they age they leak.

In fact anything with rubber is going to become a problem over time. We see it in tires and air bags, Norgren valves and coolant hoses. So as we drive aging coaches chasing leaks is going to become a part of our duties. As I find leaks and where physically possible I am replacing leakers with compression fittings. If a compression fitting is installed properly it will be leak free forever.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  11/21/2012 8:04:51 AM Sawbonz  

where does one get an ultrasonic leak detector?



Karl, Natalie, Ariel, Ian and Prancer
2004 LIBERTY ELEGANT LADY XL II #567

Dodge Ram 1500
 
  11/21/2012 1:23:22 PM Jon  

Mine is an Amprobe and doing an internet search you can likely find other brands and their distributors. I bet Amazon would list them.

A word of caution however........if you are serious about chasing and repairing leaks recognize you need to be all over your coach. upstairs, in the various bays and beneath the coach. It is slow work, requires patience, and an understanding there is no silver bullet. You can work exclusively in the steer compartment for example and to be assured you have found all leaks that can be repaired in that area you will need all types of leak detection from soapy water to a stethoscope to an ultrasonic leak detector to a bubbler such as Hector advocates. Each method has its advantages, and even with all the tools available for leak detection you still have to know how the pneumatic system works to a certain extent so you know what you are being told by the leak detection devices..

Don't let my apparently negative comments dissuade you. They are not meant to do that, but to merely help you understand an ultrasonic leak detector is but one tool, has limited benefits, and that once you become a leak detective you will also become an expert on the coach (and house) pneumatic systems.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  11/21/2012 11:22:31 PM Boateral  
air leak repair

 Spoke to Jon and Tom about the purchase of  the ultrasonic leak detector.  Each have a different type. Looking on e-bay there are many choices but  my concern was returning  it and who knows if it  works correctly once you get it.

 I landed on W.W. Grainger Co. and there complete assortment of testers are pictured on  line. Narrowed  down choices to  two. Both were at Grainger in two days,  there was no problem trying each one in the store.

My choice was there Bacharach model 28-2000, features included head set, light scale indicator meter, extension tube attachment,  sensitivity adjustment,  30 day return. 

 It works without spraying soapy water around electric components near lines. Getting a hit with soapy water will confirm the leak. Found that if the drop light is real close to tester  can produce  false readings.  This tester picks up leaks we can not hear. You think then it's a minor leak but putting about a half dozen finds resealed will make a difference.

 Installed the new air manifold today with new lines.  No leaks  detected .



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  11/22/2012 12:36:29 AM BrianE  

Steelman has the most choices.  http://www.steelmantools.com/Diagnostic-Tools.htm.  Lots of retailers including Amazon and Sears.



Brian & Beverly
99Royale,'05Tahoe
Battle Ground, WA
 
  11/23/2012 9:35:21 PM Sawbonz  

Still looking for the time to visit Di.  Oh, and Jon too.  Depends on some business things.  Pricing them online $600 is pretty pricey without some more background.



Karl, Natalie, Ariel, Ian and Prancer
2004 LIBERTY ELEGANT LADY XL II #567

Dodge Ram 1500
 
  11/23/2012 9:50:26 PM Truk4u  

Go for the Steelman Bonz, under a hundred bucks and has worked great for Brian and myself. Oh, I forgot, you have a Liberty, so the king daddy leak detector is in your future:)



Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
  11/24/2012 3:52:40 AM treedoc  

Tom  What is the model # of your unit.  Thanks Rick


Rick & Denise McLain
Hermon Maine
1996 Liberty Elegant Lady
25th year anniversary edition
Long range fuel rocks!
 
  11/24/2012 7:05:18 AM Sawbonz  

'tis true, Tom! ;)



Karl, Natalie, Ariel, Ian and Prancer
2004 LIBERTY ELEGANT LADY XL II #567

Dodge Ram 1500
 
  11/24/2012 7:30:01 AM Jon  

Don't confuse an ultrasonic leak detector ($300?) with an electronic stethoscope. Two different devices with the ability to sense different types of leaks and noise levels.

http://www.testersandtools.com/Amprobe-ULD-300-Ultrasonic-Gas-Leak-Detector.php

That was just a quick look, and there may be better deals.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  11/24/2012 7:37:19 AM Truk4u  

Rick,

It's this one: Steelman



Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
  11/24/2012 10:31:33 AM johnklopp  

As long as you Liberty guys are getting the best stuff, consider a detector with an ultrasonic transmitter. The transmitter can be placed inside the coach and you can detect wind or water leaks around the outside of the coach with the detector.

 



John Klopp
97 Royale 40' #199
06 Jeep Liberty Diesel
Mt Baldy, CA. Sterling Heights, MI

Rivets Prevent Delamination
 
  11/24/2012 10:37:55 AM Jon  

The link I provided for the Amprobe did not include the transmitter, but the one I own has the transmitter and as John correctly points out the transmitter increases the versatility of the ultrasonic leak detector.

I had a pressurized cabin in my plane and I used the transmitter to help me identify bad cabin door seals which is the exact same application John references except you would be looking for bad seals that create wind noise.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  11/24/2012 10:58:01 AM BrianE  

As Jon says, push-in fittings are fine when new but.......  Our bus is an early push-in fitting machine and we're now paying the price of manufacturing convenience. As I discover them leaking, I am also replacing the push-in fittings with tried and true compression fittings.

With numerous leaks in both the aux and suspension systems, I started with the aux system, it seems a little less complicated and is easier to access.  The original Prevost aux manifold was made up of standard pipe fittings. Installing a simple manifold simular to Als helped organize and put the various aux elements in some sort of order.  I used all new compression fittings in the new manifold.  

Having used both soap sprayers and electronic ears over the years with varying success, I recently bit the bullet and built Hectors' bubbler.  After using it, IMHO the bubbler is truly the only sure fire way of finding small leaks.   In some ways, the bubbler is an instrument of torture.  Building it is pretty simple.   The process of adapting it to various tubing sizes from the bubbler into the system takes time and patience.  Another advantage with starting the project on the aux system is that 3/8 and 1/4 inch DOT brake tubing accounts for most of the component hook-ups.  For the suspension system you may also need 1/2", 5/8" and 3/4" DOT adapters. 

I am using a 12' section of 3/8" tubing to connect the bubbler to the components.  This keeps you from having to drag the bubbler under the bus and it can pretty much stay in the same place when looking for leaks at each end of the rig.  Hector cautioned me that when using the bubbler, to leave it hooked up to a component for a sufficient amount of time for the rubber seals and airbags to stretch and find their inflated comfort zone.  Consequently I am leaving it hooked to each component for a minimum of 4 hours.  

By the way don't forget to check compressor to system supply lines.  I found a small but constant leak from the aux compressor to the aux system.  The check valve on the compressor discharge line was bad allowing aux pressure to leak back through the compressor.  It would not have been detectable without Hectors' bubbler.  Thanks Hector.




Brian & Beverly
99Royale,'05Tahoe
Battle Ground, WA
 
  11/24/2012 2:05:02 PM TexasDrifters  

See!!  I told you it would work......

From now on, your leaks finding success will be 100%.  Looks good.

Hector



Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  11/24/2012 2:55:19 PM Truk4u  

Nice job Brian...



Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
  11/24/2012 3:09:22 PM Jon  

Hector,

Is there any way to create a drawing that can be put in the articles section? Brian is right in that it is an instrument of torture because of the scope of the work required to isolate a leak. Folks need to see how simple it is, plus have a short tutorial on how and why it works.

Push in fittings are going to be our worst nightmares and leak detection is going to create a need for countless hours of effort to locate them.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  11/24/2012 4:25:31 PM Fred Schmitt  

Hey Brian,

What is the green "box" with what looks like a red button on top of if for? What does that do?



1998 Liberty XL
"Drive On"
 
  11/24/2012 8:23:00 PM Jon  

Fred,

That is a solenoid valve. Asco makes a line of solenoid valves called Red Hats or Red Tops. I can't remember the specific name. I don't know what that one is for but it obviously controls something in Brian's pneumatic system.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  11/24/2012 9:00:29 PM Fred Schmitt  

That whole manifold set up by Brian is very impressive.

 



1998 Liberty XL
"Drive On"
 
  11/24/2012 11:11:22 PM BrianE  

The solenoid is another of Hector's great ideas.  About a year ago, just after Tom had torn up his floor to fix a leak in his step slide, Hector suggested installing an ignition key actuated solenoid that would isolate the step slide and driver's seat.  Since these devices are only used when underway it seemed like a heck of an idea to me.   



Brian & Beverly
99Royale,'05Tahoe
Battle Ground, WA
 
  11/25/2012 5:28:00 AM Gil_J  

I hear that push on fittings aren't reliable.  There are two types of push-on fittings, one that is DOT approved.  Given the wide use of DOT type push-on connectors I'm wondering if the reliability issues are only with the non-DOT fittings?

I just replaced my aux air compressor motor and discovered something new.  I adjusted the compressor's output regulator to 100 psi.  This worked great until I started the engine.  With the engine compressor supplying air the aux compressor's regulator was constantly discharging excess pressure.  I assumed these regulators only regulated the output.  This is another reason for a check valve on the output of the aux compressor tank after the regulator.  I didn't have time to pick one up before we continued our trip, so yet another item for the list when we return.



Gil Johnson
1999 Country Coach XL
Country Coach...Well Engineered
 
  11/25/2012 6:05:42 AM Jon  

I seriously doubt if Prevost or the converters would use anything other than DOT fittings. If they have used non-DOT approved fittings I have not seen any. Conceptually the push on are great, but the enemy is time and since the seal is a rubber O ring that ages, hardens and eventually leaks we are destined to have problems.

We will not have aging issues with compression fittings. But when we get to the point where we have to replace leaky fittings we are also going to have to create new manifold blocks that use compression fittings. On my coach I have no less than 3 air manifold blocks that use swivel type 90 degree push on fittings. The leak potential is at the push in connection point or at the swivel. The block is too small to allow the use of conventional 90 degree compression fittings so a new larger manifold will be required or I will have to use new push on swivel 90 degree fittings.

I believe Hector said almost all his leaks were from push in fittings. When a compression fitting is leak free, age will not cause a leak.



Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  11/25/2012 6:18:14 AM TexasDrifters  

Gil,
I also have a Country Coach, so our setup should be similar.  Concerning the regulator on the aux compressor, I do not have this item.  I would get rid of it and run straight from the compressor.  The pressure switch installed on my CC has the ability to set the on/off pressure with a differential gap.  Meaning, it comes on at 85 psi and goes off at 110 psi.  With these settings, the aux air does not interfere with the Bendix engine compressor.

Additionally, I have found that the check valves in most compressors are not as tight shutoff as we need for our aux air systems.  I have mounted a double check valve in the aux air discharge line.  A word of caution, do not mount the check valves close to the compressor, but as far away as possible on the discharge line.  This will avoid any check valve damage due to hot air from a aux compressor that run alot.

The comment of Brian E concerning installing a air blocking solonoid on the air lines that supply the ISRI seat and the step slide is almost always assured to stop a few leaks.  These two items have proven to be leakers.

Good Luck.

Hector


Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  11/25/2012 6:56:24 AM TexasDrifters  

From Jon...

Is there any way to create a drawing that can be put in the articles section? Brian is right in that it is an instrument of torture because of the scope of the work required to isolate a leak. Folks need to see how simple it is, plus have a short tutorial on how and why it works.
............................................................................................................

If one checks out the current articles, an article titled "How Does the Prevost Suspension Work" can be found.  This was one of the first articles you guys posted.  Around 50 minutes into the presentation, a discussion of the bubbler is done.  Concerning posting a drawing of the bubbler, well, I reserved the actual drawings for those that participated in one of the suspension presentations I gave over a one month period of time, twice a week, late in the evenings (was offered two years in a row).  We all connected using the Internet (and our computers) and had a workshop concerning the suspension system.  The posting in the article is a recording of the last session in the first series.

I would be worth while for any new coach owners to take the time to review this presentation.  This time will be a good investment in you time.  It will save you much time and anxiety in dealing with suspension system leaks.  The suspension system is managable, but you will need basic knowledge of how the system operates at a minimum.


Hector


Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  12/2/2012 5:17:04 AM treedoc  

Jon  I went to the tools and testers site. There is a uld 300 and tmuld 300. The pic of the tmuld 300 has an added item to the right that the uld 300 doesn't. Is that a transmitter?  Rick


Rick & Denise McLain
Hermon Maine
1996 Liberty Elegant Lady
25th year anniversary edition
Long range fuel rocks!
 
  12/2/2012 5:38:26 AM Jon  

Yes. A transmitter has less value to me now that I don't own a plane. It has value in finding air leaks in door seals, but probably not in the case of owners of coaches with OTR. Open the fresh air intake on an OTR coach, start up the coach and the AC and use soapy water to see all the bubbles where air is leaking out, including the door seals and roof.

But the detector is a valuable tool.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  12/2/2012 8:28:53 PM Roger Foster  

Hector:  Please recommend a source for the back flow preventer for the aux air compressor.  Just today I replaced my aux air compressor and need a replacement check valve as the old original one is not as air tight as I would like and after cleaning made a notable improvement but not absolute air tight.  Nor bubble tight as you might say.. 

I really like your idea of doubling the back flow preventer especially down stream and distanced from the compressor. 

Thanks in advance



Roger & Micki Foster2006 XL2 Liberty DS
2008 Avalanche
Bristol, TN
 
  12/3/2012 5:58:04 AM Jon  

Roger,

I didn't keep the paperwork, but I added one on my coach and I just did a search on Amazon. They were about $15 to $20. I bought two and used one on the compressor which has a built in check valve, and to the belt tensioner circuit which did not have one whereas my 97 did have one.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  12/16/2012 3:24:00 PM Boateral  
Check valves

 When you think you do not have a check valve, look again. The Thomas Aux compressor has a fitting that could be passed by for a coupler and not a check valve.

 Pictures show differant types..

I'am telling tech service there is not one in the line. Tech service sends me a picture of what I should be looking for.......dah

  You learn something new everyday you work on one of these monsters.

 I hope this helps  PC members fixing air leaks. This $8.00 valve Pic # 2 can dump a lot of air in a few hours through the Thomas compressor.

hours.

 The last picture is the check valve installed by Prevost for mini air bags in engine compartment. 

 

 

 



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  12/16/2012 4:14:17 PM Jon  

It is a good practice to keep an external compressor check valve some distance from the compressor. The reason is the air from the compressor can be very hot and in a relatively short period of time that causes the check valve seal to fail. So to continue Al's point, you may have an external check valve for the aux compressor, but it could be where the aux compressor air line joins the coach aux air system. And to restate Al's excellent point it may look like a connector or any plumbing connection.

Nothing is as easy as it sounds.


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  12/19/2012 9:16:34 PM Boateral  
Air leak repair

 Jon, your post got me thinking. 

 Checked the temp. rating with my new valve installed at the Thomas compressor.  My replacement valve was rated at 250 deg max. As you say heat could shorten the life installed next to compressor. Marathon routinely mounts  check valve at this location. As you may be aware there Aux system splits someplace after the Thomas compressor  line. One direct line to Aux tank mounted back in the hot water bay on the passenger side. The other side of the split runs to the Aux storage tank under drivers seat. 

This rear storage tank supplies a reserve 10 +or-gals of air @ 120 lbs for the operation of the air operated in and out sewage dump hose. Another air item is the trap door on the underbody raised and lowered for travel position of sewage line and 50 amp cord.access.

The best I can tell is the split is behind the generator and nearly impossible access. Lines are different colors which ID's from front to rear on the bus. This was helpful to pressurize various lines checking for leaks

Researched a company in Minnesota which manufactures check valves. www.valvecheckinc.com

 I now have a custom made model 6200 ....400 deg heat rated, Viton gasket ,  "0"  ring seal , 3 psi cracking pressure, this is amount of air needed to open the valve when the compressor starts. Shop talk if your in the check valve business. 

Choices can be custom made setting cracking pressure with various custom stainless springs .

 Choices can be made on the valve seal and its material. Viton "0" ring is the best with air, has a long service life, heat not really an issue with Viton material used inside this valve and  service next to compressor.

 All of the internal parts for the new check valve are held in place with a snap ring. The other valve internal parts appeared  pressed in.

 

 

 



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  12/20/2012 6:05:29 AM Truk4u  

Good post Al, a couple new check valves are in my future.



Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
  12/20/2012 7:41:03 AM Jon  

Compressed air can get very hot, and I think this is why the air dryer on our coaches is located some distance from the engine driven compressor. That is why an aux compressor check valve needs to be located in such a manner to allow air temp to drop into a reasonable temperature range.

Did Marathon locate a check valve just ahead of the split?


Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  12/20/2012 11:02:48 AM Boateral  
air leak repair

  According to Marathon tech service the check valve for Aux tank service is located at the compressor.  Have few issues with check valve and should be replaced at some point as planed maintenance.

  No valve is located  at the split and there is a reason.

Another check valve does exist on top of Aux air tank under the drivers seat. This check valve is for the Marathon Air service  i.e.,air  windows, toilet, air slide doors, air floor slide.  

Supply service from tank has a direct  3/8 inch service  after going through a SMC water seperator  (this is the seperator mounted on the floor of the drivers bay)  then direct line service to  rear bedroom manifold. 

That's the newly replaced  black manifold  I  pictured back a few posts. Each system then has a regulator and has a set pressure for operation. A separate supply line from the 10 gal rear supply  runs to the  trap door regulator set at 80 lbs.  mounted  behind a service panel in water bay ( drivers side) .  With the help of an air piston raises and lowers the trap door for  access to sewer hose and 50 amp cord. 

   Sewer hose is the "hog"  for air  and as I understand air is reversed back  with an introduction of a  part called  "knife valve".  Air is supplied to this storage tank by two 3/8 inch lines ,1) direct Thomas compressor air line,  2) direct green Aux tank line.

 Assume the sewer hose is in......  press  "out"  button and you have opened the knife valve  to a  1 -1/2  inch supply direct to sewer hose that pressurizes the 4 inch hose and out it shoots.  Works perfect as long as the cap is on the end of sewer hose. The reverse happens and the sewer hose is sucked back into the bus. 

 I have tested all supply service lines on the bus with the help of my $99.00 Missouri style shop compressor. Marathon runs supply lines in one piece front to back of bus where air is needed. Keeping it as simple as possible. I would not call it simple .....but  now understand how it works.

 Back to Jon's point,   yes this check valve should be located  down the line for  longer service life.  I do have a super high heat custom valve and will be replaced a little more often then 7 years. 

 Ryan... was the contact at  Valve Check, Inc

.     

 



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  12/20/2012 12:26:34 PM Boateral  
air leak repair

 Air system components.

 TOP PICTURE......SMC water and dirt filter under drivers seat. Cleans up Marathon air going to all Marathon service.  Eagle rebuilt this filter with new "O" ring seal at cannister, new internal filter, new internal automatic drain valve.

There is a large SMC check valve located on top of green air tank 3 inch long ,color silver. I think this is the addional check valve on the Marathon service system.Tested  OK when I removed the Aux air tank completely. Taken to Eagle for under water overnight 120 lb pressure test .....yes they sunk it in a barrel of water and that's how you know your tank, check valve, welds, are tight..

 Two types of dial pressure regulators;

GENERATOR.. SMC DIAL REGULATORS......Most of the regulators are what they call, pass through , except generator mini air bags.(set 25 lbs) and  trap door, set 80 lbs.

Marathon builds a safety lock to hold  "up" in case air is lost and door lowers

 One check..... easy to make on your generator air system;

1) turn off Aux compressor

2) dump air in Aux tank, pull relief valve on top of green tank or open tank drain valve

If the regulator in generator bay is working properly mini bags should stay up, usually set at 25 lbs. This regulator has a different part number and is designed as a safety if air is lost, having a internal check valve built into the regulator. If generator is running or just sitting  keeping air  bags up so the shake won't destroy the mini air bags.

   In storage  those mini air bags should stay inflated for a long, long time. even with total loss of all  Aux air

  In my case found wrong  regulator installed on my bus. ... it also leaked

;

Regulators here are all pass through style. New manifold block nstalled.



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  1/21/2013 4:10:55 PM Boateral  
air leak repair

 Do check Valves make noise ?

 All is good one day and the next....another air leak.  Hearing a slight noise.....a little buzz,,,,coming from  aux air  tank  At first believed the cut in/out pressure valve was making internal noise. Using the electronic leak/noise detector ..  noise was coming from of all things the  large silver SMC AK4000 check valve. 

 The strange sound makes no sense. Check with Marathon Tech service learning Leon,  did'nt  recall any problems with that  SMC valve at that location. Long life trouble free, I'am told, good locaton, stays cool. 

I had spent most of the morning checking all the areas where working on the Marathon Air system  last month. Isolated systems from  last repairs, leak contiued.

 Made a call to Eagle Fluid Air in KC learning any noise inside a check valve requires replacement. Another consideration is age of part and is on the high side.  

 Brian, at Eagle suggested that if I had any check valve in my spare parts to install it right behind the present valve.  Test was a success and the air leak ended.

  new valve $19.00.



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  2/3/2013 1:34:19 PM Boateral  
Air leak repair

 The continued adventures of air leak repair.

  After replacing the air check valve on the Aux green tank a very slight leak down was still happening. Isolating zones again this leak was on the toilet air system. Using my electronic sniffer no leaks show up on the valve below that has 6 colored air lines.

 With the help of Microphor tech service in New Jersey I first isolated the feed air line, no leaks. The leak must be internal to some operation part of the Microflush toilet large grayvalve. Nearly an hour later the leak was found on the yellow air line which goes from  valve pictured below to the contents hopper. The leak was air constant which was about 10 lbs + or - in 3-4 hours measured at storage tank.  

  John ( Microflush dealer) said he gets over 100 calls a month for tech service. Has only seen this malfunction maybe 3 times  finding this leak when everything else works fine. Our toilet worked perfect.

 This leak is only detectable when you disconnect the yellow line from the sealed hopper tank. It was a last resort check as all other tests were 100 %.

 Second picture shows a metal wafer insert into a plastic bracket. I made this metal wafer-washer to stabilize mounting of two valves on this bracket. Problem is the 2 valves mounted on this bracket have different hole mount diameters, over 3/8 inch difference. Both valves must be mated secure as water under pressure transfers between valves when you flush. This plastic bracket was used in production for less then a year, I'am told. 

This wafer insert corrects the excess factory hole play, provides secure mounting of both valves on a plastic bracket. Have  3/16 inch  adjustment play, which was all that's needed.

 Our toilet is a Microflush LF-210 and no longer manufactured.  Parts are still available but extremly expensive.

This is the internal air leaking Air/Water Sequence Valve, cost $340.00.  Brass part is old style bleed off assembly,  new bleed off valve is  $52.00.  The bleed off valve is the operation adjustment.  Now  has  external adjustment  screw. required with new style  A/W Seq valve. 

 Wall mounted (not pictured)  flush handle internal valve  part also leaked air , replaced sometime ago $71.00.  

 

     



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  2/4/2013 1:18:03 PM Boateral  
Microflush toilet

 All parts in place.....it flushs,  it doesn't leak air,   Mary Ellen  is happy  !



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  3/7/2013 10:25:30 AM Boateral  
How sweet it is

 Picture shows  holding air pressure  test for 14 hours.

 Aux compressor  cut  out at  120 psi   then  power turned  off at switched  panel  

 Estimated cost ;   one  $400 electronic leak detector ,  50  gallon drum soapy water,  3 trigger sprayers,  new knee pads, probably around $1000 of parts, (toilet air parts alone over  $500).  

 Thanks John and Sue at Microphor Tech/Parts  New Jersey  who stayed with me through many phone calls. 

Mega thanks to Leon at Marathon Coach Tech service Coberg OR. for  outstanding customer service.  

 When ever a leak was found  I always  let him know the result.  Leon , remarked that rarely  learns or gets feed back of what happens in finding or fixing the problem after the customer first calls. 

 



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  3/7/2013 2:04:24 PM Jon  

Al.........If you hadn't taken a shot at us Liberty guys in the discussion of pumps VS city water I wouldn't mention your Microphor cost of parts (ignoring the time spent, frustration, and the fact when you were messing with it you knew some smart aleck was going to say something). But I thought it was worth mentioning. So I did.

But I have to tell you I am impressed with the results of your efforts. You really did a good job.



Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  3/7/2013 2:46:15 PM dtroberts  

Al,


I have never posted on here but have read since Jon and Tom started this amazing site and amzing people. 

You and this entire thread on your repairs is amazing. You have helped me a ton on my own repairs. I would be interrested in your custom air block inside the closet sometime I will get a hold of you.

Here it is: Do you marry the Marathon air to the Prevost air and leave it? You may have said and I missed it.

Some people keep them independent from one another what do you do?



Doug and Tina
2005 Marathon XLII
 
  3/7/2013 3:25:01 PM Jon  

Doug,

Generally speaking every converter makes connections to the pneumatic system on the coach at the spot designated by Prevost.

To the best of my knowledge on the coaches I have owned Prevost offers the converters two locations to connect for their air needs. One is in the steer compartment and typically has a plastic tag with the word "converter air" etched into it. Ditto for the one in the rear located behind the tag axle, passenger side to the left rear of that little compartment.

Those connection points tap into only accessory or auxiliary air. They are provided with protection valves so if something catastrophic happens the two brake systems will not suffer an air loss below the pressure needed for them to function.

From time to time we learn of someone connecting in a location other than described above. Usually we hear about it because there are problems associated with the connection point such as no protection against moisture, and other issues. While the converter air system and devices share an air supply with the bus auxiliary air systems and devices and while both generally use the aux air tank as the storage device for needed air you are not likely to find converter air system connections scattered around the coach other than the two points I described, and some may only make one connection. 

The same can be said of the coach electrical system and how the house and chassis electrical systems are isolated from one another, but do share a common connection point that is protected against one depleting the other.

Depending on how curious you are you can go to the Prevost Publications page accessible through the Prevost Car web site and pull up the pneumatic diagrams for your specific coach. It will not show anything relating to the converter, but it will show the entire chassis systems and will identify the allowable connection points.

http://prevostparts.volvo.com/technicalpublications/en/manuel.asp



Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  3/7/2013 4:19:34 PM dtroberts  

Jon,


Totally correct as always... I have located and work in all locations. Not sure about Liberty but in my steer compartment near the Norgren there is a simple yellow tab that will cut off the Marathon from the Prevost side. If you "marry" them it is possible that you may over work the compressor in the Gen bay to make up for loss of air on the Prevost side if you have leaks. However over a period of time untouched for weeks my coach maintains a great 120 psi in both front, rear and Aux. So in my instance I have "married" them. I am just never certain if the compressor is being over worked to make up the difference as I am not in my coach regulary. Just interested if Al had his married and was not sure if Liberty did the same set-up as I have been taught to let them be independant from one another not to marry them. My coach number is 10 or so away from Al's so I just couldn't imagine them being set-up any differently.


Hope this makes sense. If I get some pics I will post them.



Doug and Tina
2005 Marathon XLII
 
  3/7/2013 4:42:07 PM Boateral  


Doug, thank you for your very kind posting.  Thanks also Jon, for acknowledgeing me.

Your refering to the yellow valve on the right bulk head under the drivers seat,..... pictured ?

 This yellow plastic valve opens turning to 3 o'clock   Tag on pipe  "open only if compressor fails". The correct normal position is pictured..... 6 o'clock.

 This valve isolates Aux air supply from Prevost air supply.  Opening this valve allows unfiltered moisture air into your Prevost system coming from the green Aux air tank. 

 In  talks with  Leon at tech service  Marathon the two (2) systems should only be combined in emergency need.

 

 



2000 Marathon H # 591 w/ OTR air
2010 GMC Acadia AWD
Kansas City, MO.
There is no greater treasure than a good friend
 
  3/7/2013 5:36:53 PM dtroberts  

Al,

That was exactly my question. I was taught never to marry them just as the sticker indicates. It has been a debate for some time. However I did go against that and I did marry them a couple months back. I will revert back as suggested and repair independently as needed. Thanks



Doug and Tina
2005 Marathon XLII
 
  3/7/2013 6:24:16 PM Truk4u  

Nice Job Al, you are now our resident Microphor toilet expert.



Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
   
© 2011 Prevost Community
Top of Page