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Topic: Ride height Bag inflate / Deflate issue (Read 688 times) previous topic - next topic

Ride height Bag inflate / Deflate issue

I'm trying to fix a problem that happened on our way home a few months back.

A Ride height issue where the passenger side of the coach was leaning heavily downward, due to the fact the DS rear bag would Inflate when needed, but never deflate.

As I had fully rebuilt the 6packs about two years back, I assumed it was possibly one of the ride height valves. Due to age of the coach and no service history on much of anything, I replaced all 3 of the ride height valves. Have fully checked all 3's functionality on the work bench, prior to install. All mechanically/pneumatically perform as they should.

Replaced all 3, calibrated 8.5" ride height. All 3 valves are clocked properly for proper RAISE,LOWER,NULL position.  BUT, I still have the same issue with the same bag. When in TRAVEL mode, hand checking at the valve itself, I can rotate the valve for raise and the DS rear bags will inflate, but when I rotate it to lower, all I get is a quick pffft, not a constant draining of air as I do on the other 2. When I remove the hose at the valve, coming from the 6 pack there is no air to release.

IF I fully understand the function of the 6 pack. When the coach is placed in TRAVEL mode, TL SOL stays open all the time. Air is allowed to flow in both directions through the TLS back and forth to the bags. In TL the ride height valve allows air to flow to the bag, or allows air to be released from the bag. Said air passing first through the TLS.

I have pulled the DS Rear TLS and bench checked it as well as checked its function on the coach, and it opens when told to do so, and stays open. The plunger does move as it is supposed to when observed on the bench. Yet when in play under pressure will only allow air to pass out to the bag, but never allow that bag to deflate.
I have not yet Pulled the section where the plunger and the spring reside. Unless the rubber face of the plunger has somehow dislodged (all new plungers/springs during rebuild Toms kit) I don't see as where I would find anything, but that is my next thing to do.

Has anyone ever seen such a situation? Not many hairs left to pull out.
Thanks in advance for any input.
Mike in AL
2001 U295
8.3 ISC 350
Build 5918

Re: Ride height Bag inflate / Deflate issue

Reply #1 –
Quote from: mkc1962 –
I'm trying to fix a problem that happened on our way home a few months back.

A Ride height issue where the passenger side of the coach was leaning heavily downward, due to the fact the DS rear bag would Inflate when needed, but never deflate.

Did you check the exhaust port of the six pack manifold for blockage?  The majority of the time a corner won't dump it's due to something like a mud dauber nest in the exhaust port.  They're open to the environment.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Ride height Bag inflate / Deflate issue

Reply #2 –
Quote from: Michelle –
Did you check the exhaust port of the six pack manifold for blockage?  The majority of the time a corner won't dump it's due to something like a mud dauber nest in the exhaust port.  They're open to the environment.

Sorry for not mentioning such. I replaced those with exhaust stones and they are still 100% new and blew air through them yesterday. however, if I Understand the 6 pack function properly, those Stones / exhaust ports  only come into play when the manual LOWER is activated. The exhaust when in TRAVEL mode is actually through the bottom of the ride height valves.
Mike in AL
2001 U295
8.3 ISC 350
Build 5918

Re: Ride height Bag inflate / Deflate issue

Reply #3 –
I wasn't sure if a clogged exhaust port on the manifold would create problems for travel mode or not, so wanted to mention it.  Say, if you were leveled with a corner high and it tries to exhaust to go into travel mode - would a clogged exhaust port create an issue?
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Ride height Bag inflate / Deflate issue

Reply #4 –
What if the raise solenoid would have a piece of trash keeping the plunger from seating. That might cause that side to raise, but the ride height valve would not be able to lower that bag.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Ride height Bag inflate / Deflate issue

Reply #5 –
Quote from: red tractor –
What if the raise solenoid would have a piece of trash keeping the plunger from seating. That might cause that side to raise, but the ride height valve would not be able to lower that bag.

We had that exact problem (with a raise valve leaking through) about 10 years ago.  It was evident during regular leveling (that corner would rise to full/over height as time went on if the aux compressor ran.  Took us forever to figure out because we kept thinking the opposite corner was leaking down and were trying to find leaks there.

I don't recall anything apparent during travel mode, but we were focused on the leveling issue.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Ride height Bag inflate / Deflate issue

Reply #6 –
I'm not sure I understand the situation.
Are you in travel or level mode when this happens?
Are you saying the left rear bag is extended to much?
If the green travel light is on then the ride height valve should adjust that corner to travel height.
If the travel light is on and the left rear corner is high check the rod(arm) on the ride height valve to be sure it's not bent.
The coach should move in the direction the arm is pointing.
Rod up, coach should go up, rod pointing down coach should go down.
John Duld
1995 U320C SE 40'

Re: Ride height Bag inflate / Deflate issue

Reply #7 –
I though that I had the schematic for an air system that uses manual air height valves but I could not find one.  Do we have one that is for this coach?

Found it in the documents on this web site and verified what I was thinking.

The manual ride height adjuster  (MRHA) gets is air from the coaches air system after the the protection valve.  It always has air pressure to it when the system has air pressure above the PV.  After the air goes to the MRHA it then goes to the 6 pack.  When the level solenoids are open in the travel mode, the air passage is then connected to the air bags. While these travel solenoids are open, air should be going in and out of the bags to keep the coach level which is adjusted by the MRHA.  If the ride height is too high the MRHA release air at the MRHA and reduces the air pressure in the bags. The front bags have one MRHA in the middle that takes care of the complete front air bags and the rear has two MRHA's  one for left rear bags and one for right rear bags.

On to the problem at hand that while the coach is in travel mode, these solenoids are open.  Thus the MRHA's are either holding air, releasing air, or adding air to the bags that there are connected too.  If the bags are only able to rise and not deflate then the most likely problem is the MRHA since that is what should be letting the air release. The only other place that could keep the bags from deflating if the MRHA is operating correctly would be the travel solenoid.  It seems that this could be where the problem is since when the MRHA is set to lower pressure there is only a short burst of air, such as only the air that is between the solenoid and the MRHA. I can not think how the travel solenoid could be acting like a check valve keeping the bag from releasing air. One way to verify that the problem is not the MRHA is to add a temporary exhaust valve on the air bag side of the MRHA.  Air the bag up and then open the temporary valve.  If the bag does not lower then we know for sure the MRHA is not the problem and really looking like the travel solenoid.

As I was typing this I seem to remember someone else was having a weird air problem and they added pressure gauges at the bags to try an figure out what his problem was. Maybe someone remembers what that problem was.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Ride height Bag inflate / Deflate issue

Reply #8 –
In Manual mode the RAISE makes the rear go up until I tell it to stop. The LOWER, makes the rear go down until I tell it to Stop.

I also have an electrical bypass on the HWH Control system to allow full manual control in the event of another such system failure. I can fill the bags to the desired ride height and it stays right there until I tell it to change. IF I had any RAISE OR LOWER solenoid leaks, this would not be possible.

I'm not sure I understand the situation.
Are you in travel or level mode when this happens?
Are you saying the left rear bag is extended to much?
If the green travel light is on then the ride height valve should adjust that corner to travel height.
If the travel light is on and the left rear corner is high check the rod(arm) on the ride height valve to be sure it's not bent.
The coach should move in the direction the arm is pointing.
Rod up, coach should go up, rod pointing down coach should go down.

This happens ONLY IN TRAVEL MODE.
Yes Green light is active.
YES, DS rear will only go up in TRAVEL MODE.
All Ride height valves are new, bench tested for proper pressure function. All calibrated to 8.5" Ride height, NO rods bent or mis aligned.
IN the case of all of these ride height valves, they all are provided with constant pressure to the top of the valve.  when in TRAVEL MODE, The control side air is provided direct back and forth from the Rear Air bags THROUGH each sides TRAVEL Solenoid ( top 2 sols on the 6 pack).
The position of the control rod on the Ride height valves determines if air is allowed to go to the bag, or allowed air to be to released from the bags, through the TRAVEL SOL and out through the bottom of the ride height valve.

The DS rear will only allow Air to inflate the bags, it will not allow air to be released from the DS rear bags.
Mike in AL
2001 U295
8.3 ISC 350
Build 5918

Re: Ride height Bag inflate / Deflate issue

Reply #9 –
Quote from: turbojack –
I though that I had the schematic for an air system that uses manual air height valves but I could not find one.  Do we have one that is for this coach?

Found it in the documents on this web site and verified what I was thinking.

The manual ride height adjuster  (MRHA) gets is air from the coaches air system after the the protection valve.  It always has air pressure to it when the system has air pressure above the PV.  After the air goes to the MRHA it then goes to the 6 pack.  When the level solenoids are open in the travel mode, the air passage is then connected to the air bags. While these travel solenoids are open, air should be going in and out of the bags to keep the coach level which is adjusted by the MRHA.  If the ride height is too high the MRHA release air at the MRHA and reduces the air pressure in the bags. The front bags have one MRHA in the middle that takes care of the complete front air bags and the rear has two MRHA's  one for left rear bags and one for right rear bags.

On to the problem at hand that while the coach is in travel mode, these solenoids are open.  Thus the MRHA's are either holding air, releasing air, or adding air to the bags that there are connected too.  If the bags are only able to rise and not deflate then the most likely problem is the MRHA since that is what should be letting the air release. The only other place that could keep the bags from deflating if the MRHA is operating correctly would be the travel solenoid.  It seems that this could be where the problem is since when the MRHA is set to lower pressure there is only a short burst of air, such as only the air that is between the solenoid and the MRHA. I can not think how the travel solenoid could be acting like a check valve keeping the bag from releasing air. One way to verify that the problem is not the MRHA is to add a temporary exhaust valve on the air bag side of the MRHA.  Air the bag up and then open the temporary valve.  If the bag does not lower then we know for sure the MRHA is not the problem and really looking like the travel solenoid.

As I was typing this I seem to remember someone else was having a weird air problem and they added pressure gauges at the bags to try an figure out what his problem was. Maybe someone remembers what that problem was.


Fully agree with your suggestions.

I have sort of already done what you suggest by your last test. I have let air go to the bag, then I  slowly removed the air line at the MHRA that goes to the TRAVEL solenoid. Their should have been a rush of constant air until the DS rear bags went empty, all I got was a very short pffft.

I installed 3 new valves, the other 2 positions are working just fine. I took one of the others that are working fine and put it in the place of the DS rear, the same thing happened. The one that was at the DS Rear now in another place is working just fine The MRHA is not the issue.

I also agree I just don't see how a SOLENOID could act like a check valve on its own. And the only thing between the TRAVEL solenoid and the air bags are 2 hoses, and a machined passage in an aluminum block. However, the center of the internal plunger inside of the TRAVEL Solenoid is a rubber disk. Even though it it brand new installed less than 2 years ago, maybe that little rubber disk turned loose? acting as a flap?  My plan tomorrow is to once again remove that entire left (DS rear) TRAVEL solenoid, this time remove the plunger and check for any internal to the plunger obstruction. I do have another full spare solenoid, but really want to get to the bottom of what's going on.
Mike in AL
2001 U295
8.3 ISC 350
Build 5918

Re: Ride height Bag inflate / Deflate issue

Reply #10 –
Going out on a limb here but is it possible that something came loose inside that air bag that stops the air from coming out?
Richard & Betty Bark & Keiko our Golden Doodle
2003 U320T 3820 PBDS
Build # 6215
MC # 16926
2016 Chevrolet Colorado 4X4 diesel

Re: Ride height Bag inflate / Deflate issue

Reply #11 –
With the replacement of the ride height valves have you made sure that the main shaft isn't turned 180* out on the valve that isn't letting air pass? I know this seems like a stupid question but this has happened before.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Ride height Bag inflate / Deflate issue

Reply #12 –
Possible power to the solenoid? Easiest thing to do is swap the connection between the two rear travel solenoids. Since the one side is working correctly will be interesting if problem moves.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Ride height Bag inflate / Deflate issue

Reply #13 –
Quote from: rbark –
Going out on a limb here but is it possible that something came loose inside that air bag that stops the air from coming out?

Possible I suppose, but there are 2 air bags back there  AND i  can manually raise and lower. If it were something in the physical bag, I dont think I would be able to manually lower.

Quote from: Pamela & Mike –
With the replacement of the ride height valves have you made sure that the main shaft isn't turned 180* out on the valve that isn't letting air pass? I know this seems like a stupid question but this has happened before.

Mike

No, all is in order there. It wont let air pass in any position, and you can remove the line coming from the TRAVEL SOL and there is no air in that line other than a very short Pffft.
Quote from: turbojack –
Possible power to the solenoid? Easiest thing to do is swap the connection between the two rear travel solenoids. Since the one side is working correctly will be interesting if problem moves.

I have already tried the swapping leads as well as another electrical solenoid. Any electrical coil I have in that position, activates as it should. as well as fully removed the entire solenoid for bench testing. BUT did not open the plunger area, only visually confirmed the plunger movement through the hole. Plan this morning is to fully remove that entire SOL again and put on bench again, but this time disassemble the plunger mechanism.
Mike in AL
2001 U295
8.3 ISC 350
Build 5918

Re: Ride height Bag inflate / Deflate issue

Reply #14 –
Swap the travel solenoids if the problem moves or doesn't move you will know if it's a solenoid or something else.
John Duld
1995 U320C SE 40'

Re: Ride height Bag inflate / Deflate issue

Reply #15 –
Problem is solved.

Issue? Partly my assuming something I should have not, partly FT when building the coach really hosed up the ID numbers on the 6 hoses on the rear of this coach. Also, an electrical solenoid that had a come and go open.

Ultimately, I found the issue by having the system at working pressure and disconnecting hoses at the manifold until I found the one that made the DS rear bags go flat.

Under the coach, looking forward, DS to the left where the problem resided, 6-pack manifold facing forward, I assumed DS controls were on the Driver side of the manifold = wrong. DS solenoids were on the PS of the manifold and PS solenoids were on the DS of the manifold.

The biggest confusion was the 6 hoses that go from the 4 air bags on the rear, and the 2 that go from the MRHA valves all have numbered decals on them (30,31,32,33,53,54). However, each of these 6 hoses had one number on one end and another on the other end. In addition to my location assumption, The numbers on the DS manifold ports matched the DS bags, But they were not the DS hoses.

For example, the lines from the two DS air bags had decals 30 & 31 out by the bags, but on the other ends of those same hoses at the manifold had decals 32 & 33.
When your trouble shooting a certain line whether it be air or electrical and, they cover a distance you look for a marking/color/etc to help identify on both ends IF they have such marks. All hoses on our coach are marked with a stamped sticker/shrink wrap. In the case of our coach. All 6 of the hoses that deal with TRAVEL on the REAR, ALL were marked in this opposite way. If a hose/wire/etc has a #30 on one end, the other end should also have a #30.

Lastly, the electrical coil on the proper solenoid based on how you would touch it, would either activate or not. As I had a few spares, I went ahead and replaced Both of the rear TRAVEL coils.

I decided to go to the front 6 pack and check for this DS/PS reversal as well as hose labels. On the front, All hoses were labeled the same on both ends, and DS was DS and PS was PS.

When I finally get around to replacing my airbags, I plan to make sure all is labeled identical on both ends for all lines, as well as to make sure DS solenoids control DS and same for the PS.
Mike in AL
2001 U295
8.3 ISC 350
Build 5918

Re: Ride height Bag inflate / Deflate issue

Reply #16 –
Fantastic troubleshooting Mike!!
Richard & Betty Bark & Keiko our Golden Doodle
2003 U320T 3820 PBDS
Build # 6215
MC # 16926
2016 Chevrolet Colorado 4X4 diesel

Re: Ride height Bag inflate / Deflate issue

Reply #17 –
Quote from: rbark –
Fantastic troubleshooting Mike!!
Sure was a pain in the you know what though....

this reminds me of the time I spent over a day trying to get my fuel tank out, to find out during install the cables/hoses above it were not only running fore/aft but also had several hoses wrapped around the bundle creating a terrible snag on the fittings on the top of the tank.

I think someone with a sick sense of humor took part in building our certain coach.

Glad i really got to learn/know the air bag system in the process.....but troubleshooting mysteries is a pain.
Mike in AL
2001 U295
8.3 ISC 350
Build 5918

Re: Ride height Bag inflate / Deflate issue

Reply #18 –
Glad you found it Mike👍
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country