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Suggested places to look for air leak


Bob Nodine

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I need some education on the front air bag system and where to look for an air leak. I made 8 x 8 blocks that will just fit under the retracted leveling jacks so the coach will not drop more than one half inch from ride height when the air is dumped. After about 48 hours the coach air supply on both tanks will drop to about 30 PSI. When this happens the rear blocks are still not touching the jacks but the front is resting on the block. This tells me the rear air bags are not leaking but the fronts are. I have not started the search for the leak yet but thought I would get some input form those with experience doing this. I am guessing that if only one air bag has a leak all the air bags will deflate. Is that correct? Likewise, if there is a leak in one of the lines it will affect all four air bags, correct?

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When I was chasing leaks, I found that both of the air protections valves on the front tank were leaking around the seams. Tried to clean one and that was a no go, so ended up buying all new replacements, $13 ea x 4. went ahead a changed the rear ones too. Next were the push to fit fittings. Found a lot of those leaking as well due to age I suspect. Order a variety of those from MSC and kept some spares for down the road and grabbed a few straights as well in case I had a line get a hole in it. I did not find any of the 6 pac valve leaking or any of the air bags. Used a spray bottle with dish soap and water to locate them.

https://mpparts.com/part/n15759a-pressure-protection-valve-n15759a

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18 hours ago, ncsteve said:

When I was chasing leaks, I found that both of the air protections valves on the front tank were leaking around the seams. Tried to clean one and that was a no go, so ended up buying all new replacements, $13 ea x 4. went ahead a changed the rear ones too. Next were the push to fit fittings. Found a lot of those leaking as well due to age I suspect. Order a variety of those from MSC and kept some spares for down the road and grabbed a few straights as well in case I had a line get a hole in it. I did not find any of the 6 pac valve leaking or any of the air bags. Used a spray bottle with dish soap and water to locate them.

https://mpparts.com/part/n15759a-pressure-protection-valve-n15759a

Thanks Steve, that is helpful. Do you have a link to the push-to-fit connectors? I might as well order a few.

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Bob, Steve is spot on the only thing I can add is use a garden sprayer with kids bubbles in it much easier than a spray bottle and when I did it I replaced all my push to connect fittings with the swivel type on the protection valves. My figuring is since the valves go bad so often I would only have to unscrew the fittings next time and not have to cut and refit my air lines and buy new fittings next time.

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The link for the fittings at MSC is below. Make sure you choose the DOT approved ones, usually all brass. I  also bought a few through the local NAPA dealer as well. Also I had numerous sizes, 1/4 to 1/4, 3/8 to 1/4, 3/8 to 3/8, and a 5/8 to 3/8.  Some 90, some 45's, some swiveled and some not. They are not cheap, so you may want to see which ones are leaking, make a list and order them. I did order a few extras for late on.

https://www.mscdirect.com/browse/tn/Hose-Tube-Fittings-Valves/Metal-Push-To-Connect-Tube-Fittings?searchterm=DOT+Push-To-Connect+Tube+Fittings&navid=4287924576

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3 hours ago, miacasa_2000 said:

Bob, Steve is spot on the only thing I can add is use a garden sprayer with kids bubbles in it much easier than a spray bottle and when I did it I replaced all my push to connect fittings with the swivel type on the protection valves. My figuring is since the valves go bad so often I would only have to unscrew the fittings next time and not have to cut and refit my air lines and buy new fittings next time.

 I need to search again for leaks but I'm recovering from shoulder rotator surgery so it won't be soon . I found I can use my left hand after all .😉

 Before when I had leaks some would not show up , then I read somewhere to use bubble bath mixed rather thick and slather it on with a cheap 1 inch  paint   brush sure enough tiny bubbles appeared where I had already used soapy spray without seeing any bubbles .

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On 10/7/2020 at 5:49 AM, miacasa_2000 said:

Bob, Steve is spot on the only thing I can add is use a garden sprayer with kids bubbles in it much easier than a spray bottle and when I did it I replaced all my push to connect fittings with the swivel type on the protection valves. My figuring is since the valves go bad so often I would only have to unscrew the fittings next time and not have to cut and refit my air lines and buy new fittings next time.

Roy,

Based on a suggestion by another member I went to Walmart to purchase some kids bubbles solution but they said they were out of season and the stock was gone. So I ordered a large bottle from Amazon and it came a few days ago. Did not think about the garden sprayer and had planned to use a handheld spray bottle. I carry a sprayer in the coach and might just try that.

 

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On 10/6/2020 at 7:29 AM, Bob Nodine said:

I need some education on the front air bag system and where to look for an air leak. I made 8 x 8 blocks that will just fit under the retracted leveling jacks so the coach will not drop more than one half inch from ride height when the air is dumped. After about 48 hours the coach air supply on both tanks will drop to about 30 PSI. When this happens the rear blocks are still not touching the jacks but the front is resting on the block. This tells me the rear air bags are not leaking but the fronts are. I have not started the search for the leak yet but thought I would get some input form those with experience doing this. I am guessing that if only one air bag has a leak all the air bags will deflate. Is that correct? Likewise, if there is a leak in one of the lines it will affect all four air bags, correct?

Yes on your diplomat, if no air leveling , all 4 front air bags are plumbed together  to the ride height adjuster .
 

Bob,

Time to spray down all the push fittings with soapy water. If you find a leaky push fitting , square the end of the tube or at least shave off a small amount of the tube, maybe 1/16”, wipe the end  off with some Vasoline and put it back in. That makes it slide in easy.

Check to see if air bags have reducers that might leak. 
 

Then there is the possibility of a bag leaking or the ride height adjuster itself. 


I wonder if a stethoscope might help hear the air moving. 
 

bill g 06 dynasty

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21 hours ago, ncsteve said:

The link for the fittings at MSC is below. Make sure you choose the DOT approved ones, usually all brass. I  also bought a few through the local NAPA dealer as well. Also I had numerous sizes, 1/4 to 1/4, 3/8 to 1/4, 3/8 to 3/8, and a 5/8 to 3/8.  Some 90, some 45's, some swiveled and some not. They are not cheap, so you may want to see which ones are leaking, make a list and order them. I did order a few extras for late on.

https://www.mscdirect.com/browse/tn/Hose-Tube-Fittings-Valves/Metal-Push-To-Connect-Tube-Fittings?searchterm=DOT+Push-To-Connect+Tube+Fittings&navid=4287924576

Thanks for the link Steve, I saved it.

20 hours ago, Ray Davis said:

 I need to search again for leaks but I'm recovering from shoulder rotator surgery so it won't be soon . I found I can use my left hand after all .😉

 Before when I had leaks some would not show up , then I read somewhere to use bubble bath mixed rather thick and slather it on with a cheap 1 inch  paint   brush sure enough tiny bubbles appeared where I had already used soapy spray without seeing any bubbles .

Will keep that in mind Ray.

 

3 minutes ago, Hotrod said:

Yes on your diplomat, if no air leveling , all 4 front air bags are plumbed together  to the ride height adjuster .
 

Bob,

Time to spray down all the push fittings with soapy water. If you find a leaky push fitting , square the end of the tube or at least shave off a small amount of the tube, maybe 1/16”, wipe the end  off with some Vasoline and put it back in. That makes it slide in easy.

Check to see if air bags have reducers that might leak. 
 

Then there is the possibility of a bag leaking or the ride height adjuster itself. 


I wonder if a stethoscope might help hear the air moving. 
 

bill g 06 dynasty

Thanks Bill. I am the second owner of this coach and purchased it when it was one year old. I am quite sure reducers have not been installed in the air lines to the bags. I suspect the ride height adjuster and plan to spray that down and all the connections. That is a good tip on squaring the tubing end and re-inserting.

Hope you and Peggy are doing well and hope to see you in Florida in Jan.

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I had problem with front dropping over night when leveled with air leveling system. Both rear front airbags had several little wires from steel belted tires imbedded in them and caused a very slow leak. What made it hard to find the wires were imbedded on the back side of the airbag which was hard to get to where you can see it. Once we found it you could feel the wires by running your hand over the back side, carefully as they are sharp. 

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Bob,

I am still hunting air leaks on my coach.  I am dropping 85 PSI in 24 hours.  I’ve done a lot of looking and found enough leaks to make the Titanic look seaworthy.  I have determined that none of my leaks are in the air suspension- so far.  Here are a few of things I’ve tried/discovered.

I ordered fittings and lines from this company.  They are out of Canada and it took a week to get the items, but they had everything I needed/wanted.  https://www.new-line.com/
just type in “DOT brake fittings” in the search bar.  You can find the fittings all over the Internet.   I found that you need to try a bunch of different search terms.  Try, push to connect, PTC, tube fittings, etc.  make sure you use the term DOT, it will help narrow the solution.  
As far as the soap solution, I am using Dawn dish soap and water in a handheld garden sprayer.  I think it was $4 or $5 at Home Depot.  I have seen the kids bubble stuff at the local Dollar Tree and might pick up some of that.

I don’t know if you’re aware of this, but they make nylon plugs that fit into the fittings, too. I will use these to isolate various parts of the system.  I ordered the 1/4, 3/8 and 1/2 inch sizes.  I have been unable to find a 5/8 plug, but have not stopped looking.  Your local NAPA might have the plugs, or they can get them.  

If you look at my post about air leaks, I think I attached the schematic for my unit.  You’ll see that you can isolate the front bags as a set or individually.  I’m on my iPad now, so I can’t find the file.  Let me know if you can’t find it on here and I will get on the PC and send it.  
Good luck

Dan

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I tried the suggestion of a garden sprayer from @miacasa_2000.   Used the same Dawn solution but now with a pumped-up garden sprayer my spray range was about 8' or more.  That enabled hitting every fitting and line visible from either side.  No bubbles.  Wondering if the Kids Bubbles would do any better than a Dawn solution.

I know I have a leak in the step-cover pneumatic cylinder, but I turned the screws all the way down on the MAC valve.  I think somewhere else is still leaking.  The airbags stay firm with the HWH system shut off so I think that eliminates anything on the bag side of the HWH 6-packs.

Has anyone tried an electronic leak detector?

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Bob:  I had a similar problem and it was the ride height adjuster that was leaking.  There is only one adjuster for the front air bags and if it is leaking, then the front bags should deflate evenly.  Just a thought.

 

Bob L,  08 dynasty

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On 10/8/2020 at 12:37 PM, Jerry Olson said:

I had problem with front dropping over night when leveled with air leveling system. Both rear front airbags had several little wires from steel belted tires imbedded in them and caused a very slow leak. What made it hard to find the wires were imbedded on the back side of the airbag which was hard to get to where you can see it. Once we found it you could feel the wires by running your hand over the back side, carefully as they are sharp. 

Jerry,

I sure hope that is not the case but I can see how that would happen as everything the tires pick up gets flung around the wheel well.

 

22 hours ago, dandick66 said:

Bob,

I am still hunting air leaks on my coach.  I am dropping 85 PSI in 24 hours.  I’ve done a lot of looking and found enough leaks to make the Titanic look seaworthy.  I have determined that none of my leaks are in the air suspension- so far.  Here are a few of things I’ve tried/discovered.

I ordered fittings and lines from this company.  They are out of Canada and it took a week to get the items, but they had everything I needed/wanted.  https://www.new-line.com/
just type in “DOT brake fittings” in the search bar.  You can find the fittings all over the Internet.   I found that you need to try a bunch of different search terms.  Try, push to connect, PTC, tube fittings, etc.  make sure you use the term DOT, it will help narrow the solution.  
As far as the soap solution, I am using Dawn dish soap and water in a handheld garden sprayer.  I think it was $4 or $5 at Home Depot.  I have seen the kids bubble stuff at the local Dollar Tree and might pick up some of that.

I don’t know if you’re aware of this, but they make nylon plugs that fit into the fittings, too. I will use these to isolate various parts of the system.  I ordered the 1/4, 3/8 and 1/2 inch sizes.  I have been unable to find a 5/8 plug, but have not stopped looking.  Your local NAPA might have the plugs, or they can get them.  

If you look at my post about air leaks, I think I attached the schematic for my unit.  You’ll see that you can isolate the front bags as a set or individually.  I’m on my iPad now, so I can’t find the file.  Let me know if you can’t find it on here and I will get on the PC and send it.  
Good luck

Dan

Dan,

Excellent information. Thanks for passing that on.

 

18 hours ago, Bobbyboy said:

Bob:  I had a similar problem and it was the ride height adjuster that was leaking.  There is only one adjuster for the front air bags and if it is leaking, then the front bags should deflate evenly.  Just a thought.

 

Bob L,  08 dynasty

Bob,

I think that will be the first thing I spray with the bubble solution. Been busy doing preventive maintenance the last few days, such as oil change and filters. Going to do the generator today so it may be a good time to spray that valve.

 

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  • 2 weeks later...

Each time I find a leak and fix it there' little change.  Last week I found the pneumatic cylinder  for the step cover leaking.  I shut it off but the air loss still remains.  Overnight the air pressure goes down to the 40s.  I've been spraying with dawn solution everywhere I can.  That's how I found the leaks fixed so far.  Trying a mechanics stethoscope to see if I can hear; don't know if that will even work if there is a line leaking.

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I also have a random leak in the step cover cylinder when retracted, 50/50 chance that it leaks so we just cycle it again. Eventually, I plan on taking it out to see what can be done but wondering if anyone has already done that and if there is a way to rebuild it and what may be needed ahead of time?

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On 10/9/2020 at 8:27 AM, rpasetto said:

I tried the suggestion of a garden sprayer from @miacasa_2000.   Used the same Dawn solution but now with a pumped-up garden sprayer my spray range was about 8' or more.  That enabled hitting every fitting and line visible from either side.  No bubbles.  Wondering if the Kids Bubbles would do any better than a Dawn solution.

I know I have a leak in the step-cover pneumatic cylinder, but I turned the screws all the way down on the MAC valve.  I think somewhere else is still leaking.  The airbags stay firm with the HWH system shut off so I think that eliminates anything on the bag side of the HWH 6-packs.

Has anyone tried an electronic leak detector?

I bought an electronic leak detector last year, and found 0 leaks with it.   I’m not sure if I wasn’t using it right, or if it was bad out of the box, but for me it was a total waste of money.   Soapy water is the only thing that’s worked for me.

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Put a shut off valve on the feed to the MAC valve for the step cover solenoid.  Now another leak ... the control for the door air-seal.  Sprayeing multiple times with dawn solution never produced bubbles but my wife heard the leak.  We couldn't pin the sound down to whether its the Norgren pressure control or the valve (?) to the left in the picture below.  The Norgren control seems to be part# ??07-100-RN.  The valve has the label KIP Inc Valve No 1x1181.  Doing some searching after I test to see what's actually leaking in the assembly.  If anyone knows that part#, let me know.  

 

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Update.  I tested the pressure control for the door air seal off the coach with my air compressor.  The leak is easy to hear in the quiet of a garage.... hard to see bubbles.  This pressure control is like the tag axle control except it's rated at 4psi... very low pressure so maybe that's why it was easier to hear then to see bubbles.

Hotrod told me about a solution;  indentation in the rubber stop where the plastic pin from the diaphragm shuts off the air flow.  Not a good picture below but the worn part shows where the pin is not seating.  Bill told me to sand down the rubber until flat.  Put it back together and I could not hear leak, thanks to Bill.  I don't know how long the sanded-down rubber seal will last.  Hopefully long enough to go on to the next fix-er-up project.

 

image.png.54c1e3aea7bd7d515a9fca6bee2e2b22.png

 

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3 hours ago, rpasetto said:

Update.  I tested the pressure control for the door air seal off the coach with my air compressor.  The leak is easy to hear in the quiet of a garage.... hard to see bubbles.  This pressure control is like the tag axle control except it's rated at 4psi... very low pressure so maybe that's why it was easier to hear then to see bubbles.

Hotrod told me about a solution;  indentation in the rubber stop where the plastic pin from the diaphragm shuts off the air flow.  Not a good picture below but the worn part shows where the pin is not seating.  Bill told me to sand down the rubber until flat.  Put it back together and I could not hear leak, thanks to Bill.  I don't know how long the sanded-down rubber seal will last.  Hopefully long enough to go on to the next fix-er-up project.

 

image.png.54c1e3aea7bd7d515a9fca6bee2e2b22.png

 

Rick,

I have a good feeling about that repair. The rubber seat where indented was hard if not brittle from age and chemical reactions.
 

Refinishing / sanding the seat surface flat , which it no doubt was when new, has taken the hardened surface layer of rubber off, exposing new more flexible rubber to seat the pin to. 

In any case since the repair cost nothing, you are ahead from the get go:)

Here is a picture of one I sanded but it’s also not that great.

image.thumb.jpeg.5cadf4d9c01c09cc2c80ec3b76406370.jpeg

bill g

06 Dynasty

 

 

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I replaced my leaking parking brake valve before our latest trip, and about 4 hours into the drive I start hearing weird noises from the left console.   After a bit I realize I’m hearing a big air leak and I can see it on the air gauge cycling the compressor about every 2 minutes and getting louder as pressure builds.   I figured it was one of the lines or connections to the valve, pull over and find the new valve leaking air from a seam in the plastic.   
    
We are traveling in Florida, so I called lazy dayz for the part, they didn’t have one and directed me to Napa.    They said at least two weeks, none in any of their warehouses.    So I ordered a high pressure

3-way ball valve to use in the meantime.    
 

Does anyone know if there is a similar replacement valve that isn’t plastic?

 

My coach has the midland KN20033

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7 hours ago, granvillebarker said:

I replaced my leaking parking brake valve before our latest trip, and about 4 hours into the drive I start hearing weird noises from the left console.   After a bit I realize I’m hearing a big air leak and I can see it on the air gauge cycling the compressor about every 2 minutes and getting louder as pressure builds.   I figured it was one of the lines or connections to the valve, pull over and find the new valve leaking air from a seam in the plastic.   
    
We are traveling in Florida, so I called lazy dayz for the part, they didn’t have one and directed me to Napa.    They said at least two weeks, none in any of their warehouses.    So I ordered a high pressure

3-way ball valve to use in the meantime.    
 

Does anyone know if there is a similar replacement valve that isn’t plastic?

 

My coach has the midland KN20033

That is a common item so I would think local truck part supply houses would have one.

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