Valid Leveling Ride Height Air Squeal/Sound

[ziaptrn]

Hello all -

Our new-to-us 2008 Monaco Dynasty with S-chassis has made a strange whistling/squeal-type sound from the right front area whenever the right frontair bag(s) fill(s) or exhausts air.
I initially thought that the ride-height valve was making the whistling sound, so I replaced the valve in the front (1 valve for both sides of the front axle) and also replaced a leaky pressure protection valve. After that, I removed the front Valid leveling manifold and cleaned everything and replaced all of the o-rings, lubricating them properly etc. I have adjusted the ride heights spot-on to manufacturer specs and the coach drives like a dream. The auto and manual leveling features both work perfectly, and there are no errors on the control panel for leveling or anything else.

The noise was present before the ride height valve, o-ring, and pressure protection valve replacements and persists afterwards, so the changes I made did not affect anything besides the leaky pressure valve. The bags hold air 5-7 days with no loss, and then very slowly after that.
The issue is that every time we hit a bump or the front wheels moves up or down, a relatively brief whistle/squeal that clearly is made by air moving is produced. After miles and miles of eeeek-whine....eeeek-whine...eeek-whine.... this becomes very tiring to hear.
The sound also is produced when the coach has been leveled using the control pad and then I press "Travel Mode" and the right side adjusts up to the proper height. The sound persists until the coach achieves the proper ride-height, then stops until the next bump or self-adjustment while driving, and then the eeek-whine starts again.

I've checked the shock absorbers and entire front end (tie rod ends, etc.) and cannot reproduce the sound with movement alone. I have lubricated all of the zerks several times as well. I am attaching an audio file where I was able to capture the sound while under the bus. The audio captures the response to pressing the auto-level button (exhaust noises...pffft pffft pffft) followed by pressing the Travel Mode button which produces the whine/squeal. Where the rig is right now, it is really pretty level, so it doesn't take much exhaust to lower to the level position. The return to ride height is relatively quick, but the sound is repeated each and every time the air returns to inflate the front to ride height. There are 2 cycles of the Auto Level followed by Travel Mode actions captured in the audio file.

I have listened and listened and listened and felt parts for vibration and cannot isolate anything vibrating or clearly responsible for the sound.

Any suggestions or pointers for where the restriction to flow may be found, or where to look to stop the noise?

Apologies for the long post, but I'm trying to be thorough and precise and not forget anything. I am hoping perhaps someone else in the hive-mind has encountered this or similar before. Valid Mfg responded that they were responsible only for the electronics of leveling and the manifold itself, and could offer no assistance, adding that it didn't sound like it was air moving through the manifold itself producing the sound.

John

[Frank Bergamo]

The door may have an inflatable air gasket. The front door is a common place for air leaks. That might be a good place to start. Hope this helps.

[gdroberson]

my coach has a 4inos hose on the valve where the air comes out and that keeps it from whistling

[Old Dog]

Sounds just like playing a harmonica and I suspect it's a similar situation. You only have one ride height valve in the front. The air system for the front is pretty basic, once you place the system in travel mode it energizes a solenoid to supply air to the ride height valve which meters air in/out of the front bags to maintain height. 

When you were shifting from level to ride height was the coach going down, i.e. exhausting? If so try plugging the exhaust port hose on the ride height valve. Is the end of the exhaust hose flattened or squeezed together. You may also try removing the exhaust hose.

Only 2 sources I can think of and you've already replaced or serviced both. Not sure this helps.

[Tom Cherry]

43 minutes ago, Frank Bergamo said:

The door may have an inflatable air gasket. The front door is a common place for air leaks. That might be a good place to start. Hope this helps.

The air seal does not inflate, assuming the solenoid or the Mac valve is opened until a set of conditions is met. Typically, that is around 5 MPH. That is one way.  The other is ignition on and in drive. If the engine were idling and the parking brake off and your foot in the brakes, it would be difficult to open the door.

Monaco changed the logic circa 2006 or so and went to the transmission signal.  Sort of like the Travel mode would trigger it  it also has to have a deflate logic, otherwise the door is wedged in place

The easiest way to test and eliminate this is to splice in a T fitting to the line going to the seal. Put a hose on it and get a low pressure gage 0-10 psi or so 

tape it on the outside of the windshield and drive and observe. If there was a leak at a bump, you would see it. 

The other way is pressure decay. Bypass the solenoid. Put a 1/4 turn on/off valve right after the regulator. Put in the T and hook up the gage.  Then open the Valve and let the regulator pressurize the seal. Typically 5 PSI. CLOSE the on/off valve and monitor the pressure for a period of time.

 

 

 

[Frank McElroy]

Since this is a new to you coach and if I understand your post correctly, you can hear the whistling noise not only on the road traveling but also stationary while airing up, I would take a very close look at the size of the air lines and air fitting connecting the front air bags to the ping tanks.  On your coach, you have 2 ping air tanks.  One tank for the steer axle drivers side and one for the passenger side.  If someone replaced the large diameter hose between the front air bags and the ping tanks with a smaller diameter hose, the air velocity on a smaller diameter hose might be causing the whistling noise.  Also, if the front air bags were replaced with a small diameter air outlet, this would cause an air restriction.  My advice is to inspect the airlines between the 4 front air bags and the 2 ping tanks to be sure someone didn't replace a line or airbag with a smaller diameter part.

Ping tanks are used to increase the air volume of the front suspension air bags to give that nice soft ride up front on Dynasty and above model coaches.  However, the air lines and fitting must be large enough to easily handle rapid air movement between the air bags and the ping tanks.

Below is an air diagram for your coach.  In the color picture on the right side shows one end of a ping tank on my 2008 Dynasty with a #12 air line (far lower right of the picture).  If I'm not mistaken a #12 is 5/8" internal diameter.  This large air hose shown in the picture is connected to just one of the front airbags.  The picture doesn't show it but at the other end of this tank there is another #12 air hose going to the other airbag on the same side of the axle.

[ziaptrn]

Thanks so much to all who have responded to date; each is helpful in its own way as I continue to learn.

1. I don't believe that it is the door seal, and I don't know that the rig actually has a door seal. Now I get to go and have a really close look at that area and investigate. I do understand the concept, but don't think the door seal is what is squealing. The sound is from under the coach, and the recording that I posted was originally a video from my cell phone, and I stripped away the sound to keep the file size down and allow posting. 
2. The front right ping tank sounds like a very likely candidate. The sound does come from the R front of the rig much moreso than the left, and the diagram posted helps immensely.
3. The sound that I recorded occurred each time the coach moved from leveled (lowered with bags exhausted of some air) and was rising (bags filling back up to ride height). It doesn't squeal when moving from ride height to level/lowered.
4. This is exactly the kind of information that I need versus throwing parts and lines and fittings at everything - especially when it doesn't leak now. I'm sure I could fix the introduce some leaks in short order.
5. Again my sincere thanks to the group. I'm headed under the bus today and will check out all line sizes and fittings on the R (passenger) ping tank, etc. To the best of my knowledge, none have been replaced, but the rig is a 2008 and I never cease to be amazed at the "repairs" that have been made on other rigs. I think the best one was a Prevost that had a leaking toilet valve that had been 'repaired' with nylon fishing line and an old t-shirt to catch drips. Nothing visible until you disassemble, naturally.

[Frank McElroy]

If all the air bags and hoses to ping tank are factory.  Try to isolate the location of the whistle using a length of 1/2" tygon tubing like a stethoscope.  One end near where you think the whistle is and the other end my your ear.  You could also have a failing air hose with an internal flap vibrating under rapid air flow.

[Frank McElroy]

45 minutes ago, ziaptrn said:

Thanks so much to all who have responded to date; each is helpful in its own way as I continue to learn.

1. I don't believe that it is the door seal, and I don't know that the rig actually has a door seal. Now I get to go and have a really close look at that area and investigate. I do understand the concept, but don't think the door seal is what is squealing. The sound is from under the coach, and the recording that I posted was originally a video from my cell phone, and I stripped away the sound to keep the file size down and allow posting.

I have the same model as you.  You do have an air gasket door seal. The regulator is visible when opening the generator door.  It is located just above the air tank drain outlets.  The door seal pressurizes when the trans is put in gear.  That's why you should never open or close your door unless the transmission is in neutral.  Otherwise you run the risk of tearing the rubber air gasket seal.  It that happens you will hear wind noise from the door at highway speed.

[Tom Cherry]

Yes.  The Dynasty does have an air bladder door seal.  It is for wind noise and maybe a second level of protection for blowing rain and moisture.

No.  I don’t think that is the issue, if you run out of things to chase ….and there are many  that are a much higher priority, this is how you do it.

BOGO.  The air seal bladder is more scarce the the proverbial poultry dental work.  Therefore be advised to make sure respect it and are careful.  A lot of folks like me use DuPont Kryrox GPL 205.  This what a lot of antique and muscle car owners use annually to protect weatherstripping and gaskets.  I do external gasket and the air seal.  Don’t panic on the price, a tube will last several years and it takes all of 10 minutes to do and the door is quieter.

[ziaptrn]

And danged if it doesn't! You fellas are awesome.

I even went and tested it, opening the door, starting the engine, and then putting the coach in "Drive". Up inflated the seal, pretty as you please. I had seen the seal before but believed that it was simply a rather routine rubber gasket. 

I do have a whistle at 55+mph that is the last thing on the list to tackle. That will be next after I figure out the air harmonica!

Thanks for the education. I LOVE it.

John

[Tom Cherry]

1 hour ago, ziaptrn said:

And danged if it doesn't! You fellas are awesome.

I even went and tested it, opening the door, starting the engine, and then putting the coach in "Drive". Up inflated the seal, pretty as you please. I had seen the seal before but believed that it was simply a rather routine rubber gasket. 

I do have a whistle at 55+mph that is the last thing on the list to tackle. That will be next after I figure out the air harmonica!

Thanks for the education. I LOVE it.

John

Good....  Glad to be of help.  

NOW....Air Squeal at highway speeds.  Look at the frames around the windows up from.  PROBABLY not the windshield.  My Driver's side window has corners.  Doesn't matter if it a 90 deg of an angled one.  The "TIP" of the corner where the frame came together is a problem area.  If the sealant inside leaks just the tiniest....you will get a high pitched squeal. I used Blue Tape and started checking the joints where the window frames came together.  DRIVE...LISTEN....Stop....  Move Tape to another suspect. 

That is the way you isolate an air leak.  MAYBE the windshield.....but it would be at a joint in the metal. 

Good Luck.  NOW you know about the air seal and also how to protect it.  There has only been one person, in 13 years, my BEST memory that found a replacement one.  Most others just use bicycle patches and go to church regularly and include their MH in their prayers...

[ziaptrn]

Follow-up:

Today I got an automotive stethoscope and listened to all of the fittings and tanks. The port on the front tank where I replaced the failed pressure protection valve was super noisy when I pressed the tip of the stethoscope to the fittings, and I could hear even more squealing than I could with ears and transmission through the air. A trip to the parts shop to replace the fittings with new compression-style fittings (which I prefer to the push-to-connect oem style), and I crawled back under and replaced the trio of outputs. Photo of old adapters in place and removed attached.

This yielded about a 50% reduction in the squeal sound on filling of air bags, but I can say that it isn't the manifold or the ping tank or the ride-height valve. The entire front tank continues to vibrate and makes the squealing sound. It is easy to hear when pressing the stethoscope tip to any part of the front tank. The sound is reduced in volume now but still is present. Incidentally, when I blew through the removed fitting (pic attached), I could easily hear whistling noises with just my breath alone. The adapter pieces clearly were not helping, and I do believe that the front end rises and falls more quickly and smoothly before, though this could be simply confirmation bias.

So now I'm poring over the schematics and looking to see where air could/should be moving in/out of the front tank when the air is leaving the tank to supply the valves and manifold and raise the air bags. There must be some remaining stricture, because if you press the metal tip of the stethoscope to the front tank itself, you can absolutely hear the squeal and it is the same one that is heard for the initial complaint. I can't clearly hear the sound downstream from the front tank on any of the parts (ping tanks, rh valve, etc.) Again, the sound is present only when air is leaving the front tank, and not when the system is leveling and exhausting air.

I'm also attaching a file with the OEM schematic from Valid, which is exactly what I have installed (colored lines correct and everything). This helps but not with the plumbing to and from the front tank, which is where I believe I have isolated the issue.

More as progress continues, and thanks again to everyone who has contributed!

John

 

 

226387386_LevelingSystemColorDiagram.pdf

Edited November 2, 2022 by ziaptrn
remove excess photos

[Frank McElroy]

This is what OEM fittings look like on the front air tank of my 08 Dynasty.  Compare this to the air schematic.  Yours looks modified to me.

Since after changing the manifold you still hear the whistle, I'd change the PPV.  Likely it can't handle the air volume.  The PPV's on my coach have 2 air outlets vs only one on yours.  (BTW -  looks to me like yours has been replaced since it left the factory.)

Please post a picture so I can see all air connections to the dry side of the front air tank. 

 

[Ivan K]

There is a one way valve inside the tank. If the wet side was emptied, would it still whistle...

[ziaptrn]

Ivan - thanks for the information. I wonder if that valve can be replaced without replacing the entire tank? Or possible to lubricate it somehow? Food for thought.

Frank - I've attached a photo of the front tank. I don't think that it has been modified, but who knows? You can see where I replaced the air bag fitting in the new pic attached. I do know that Monaco commonly assembled rigs based on their mood that day (or so it seems) and didn't always connect everything the same way. I see where you have what I think is the air horn feed with a pressure-protection valve, but mine has the air bag supply in that spot and a plug in the next hole to the right in the photo where your air bag supply ties in. My horn works, so it gets air from somewhere, but not the same as yours, apparently.

I'm still chasing squealing 😉

John

[Ivan K]

IF it turned out to be in fact the valve on the internal bulkhead, it normally should be replaceable through a port on its side. Certainly not easy, depending on access in that area.

[Frank McElroy]

52 minutes ago, ziaptrn said:

Ivan - thanks for the information. I wonder if that valve can be replaced without replacing the entire tank? Or possible to lubricate it somehow? Food for thought.

Frank - I've attached a photo of the front tank. I don't think that it has been modified, but who knows? You can see where I replaced the air bag fitting in the new pic attached. I do know that Monaco commonly assembled rigs based on their mood that day (or so it seems) and didn't always connect everything the same way. I see where you have what I think is the air horn feed with a pressure-protection valve, but mine has the air bag supply in that spot and a plug in the next hole to the right in the photo where your air bag supply ties in. My horn works, so it gets air from somewhere, but not the same as yours, apparently.

I'm still chasing squealing 😉

John

Ivan gave a great suggestion.  Air the system up until you hear the governor kick off, shut off the engine, dump the wet tank then lower and raise the front axle and see it you still hear the whistle.  If you don't, likely it's the internal wet/dry tank check valve.  If you do, it's likely the PPV.

[96 EVO]

Ha!

Removing that valve looks like that old children's game 'Operation', just with higher stakes if you touch the walls, or drop the valve 😷!!

[Frank McElroy]

4 minutes ago, 96 EVO said:

Ha!

Removing that valve looks like that old children's game 'Operation', just with higher stakes if you touch the walls, or drop the valve 😷!!

Yep, after reading the procedure to change it which often requires the tank to be removed, you sure hope that you never need to replace one.  Luckily they rarely fail. 

But I bet there are a lot of coach owners out there that never test whether their primary and secondary air tanks hold pressure if the wet tank is dumped.  I also bet that few owners ever test to be sure their primary or secondary tanks hold air if one or the other dry air tank drain valves are opened.  So few would actually know if they had internally failed check valve on the wet/dry air tank or the parking brake air release valve located on the front secondary air tank.

[Ivan K]

7 minutes ago, Frank McElroy said:

Yep, after reading the procedure to change it which often requires the tank to be removed, you sure hope that you never need to replace one.  Luckily they rarely fail. 

But I bet there are a lot of coach owners out there that never test whether their primary and secondary air tanks hold pressure if the wet tank is dumped.  I also bet that few owners ever test to be sure their primary or secondary tanks hold air if one or the other dry air tank drain valves are opened.  So few would actually know if they had internally failed check valve on the wet/dry air tank or the parking brake air release valve located on the front secondary air tank.

Great picture, Frank. If it really came to removing the valve, hopefully it is salvageable because I don't think you can get them anymore, they are now permanently welded in, so they can't be removed and the vehicle driven without them if plugged. But there are still ports for "temporary" bypass, like in John's picture.

[96 EVO]

Yeah, no doubt something would be in the way of getting that long of an extension a straight shot thru that hole in the end of the tank, while it's in place!

[ziaptrn]

Guys - naturally, there are huge metal chassis swing arms at both ends of the tank roughly 4" from the end. So no extensions allowed, etc.

That said, the tank appears to be held in place by 4 bolts and nuts into a bracket, and wouldn't be that horrible to drop Even if not removed completely, there is plenty of room once the tank drops maybe 6" and that doesn't look like a huge deal.

I'm going to hope that it is the 2nd PPV valve on the dry side. I'm looking now to source a new valve and a triple-t to try and replace that. It won't offend me if I replace the ppv and that isn't the culprit, cos I'll know the valve is good (from a prevention standpoint) and they aren't that expensive. PLUS if replacing the PPV stops the squeal, the access is so much easier than dropping the tank and then playing "Operation" 🙂

I will definitely check the internal valve, however, by draining the wet side and see what happens. More to follow...

John

[Ivan K]

4 minutes ago, 96 EVO said:

Yeah, no doubt something would be in the way of getting that long of an extension a straight shot thru that hole in the end of the tank, while it's in place!

Sometime ago I looked at mine and it would be doable with the wheel removed and suspension supported at certain height to get to it over the h-frame. Still hope it never comes to it.

[ziaptrn]

Update -

Hi guys (and gals). I filled up the air tanks with the engine running and set the rig to Travel Mode with all bags inflated. I then shut off the engine and drained the air from the wet side of the front tank. Back at the driver's seat, and I pressed Auto to level the rig with the key on but the engine off. All worked fine. Leaving the wet side valve open and engine off, I then pressed Travel Mode to raise the rig back up. Lo and behold - the same squealing sound. So...if I understand correctly...the issue is not the inner check valve between the wet and dry sides. Huzzah!

Additional note: I left the wet side open to atmospheric pressure for an hour and the rig didn't budge or lose any air - which again I believe means that the inner check valve on the front tank is not leaking 'backwards.' Nice to know.

I have ordered a new pressure protection valve that is due to arrive on Friday, and I'll plumb that into place and see what we get.

Thanks again to all. The sense of support is tremendously reassuring.
 

John