Leaning Coach, Air Check Valves

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Leaning Coach, Air Check Valves

September 22, 2012, 12:56:48 am

For weeks parked on a sloped site, we had to re-level the coach and use the engine to rebuild air pressure in the tanks rather than use the auxiliary compressor.

The HWH auto level function did not maintain level though it showed it to be level (by the lights). A two foot level and visual observation clearly showed a lean and cabinets and doors behaved as such. In from one to four days the coach would raise overall an inch but also about 1.5 inches more on one side, causing the coach to lean. In this time, the dash air gauges showed the psi falling in 48 hours from 132 psi (freshly filled by cranking) to 70 - 75 psi.

When this happened, I talked to Gary Omel and MOT folks and Don Hay. THe opinion was that we must not allow the 12 v auxiliary compressor to operate for long periods (15+ minutes) to try to keep (build) the psi to the proper level as it would burn up the compressor (very expensive) and the only temporary management fix was to crank the engine to re-build the pressure, re-level and repeat as needed. This was not a good way to "live" but apparently the only way. I pulled the fuse on the auxiliary compressor to keep it from kicking in when the tanks dropped down to 65 psi.

The cause. On this coach, 2001 U320, the auxiliary compressor is not designed to fully pressurize the entire system and pulling the fuse to protect it was very important. MOT found when we got back there that three check valves were "bad" . For this coach, there are three air tanks under the front. Two large and one smaller, the smaller one being the one used to maintain level and the slide bladder. The larger tanks are for the brakes and other purposes. Check valves were allowing air to move back and forth between the small tank and the two larger tanks and even back to the auxiliary compressor. So rather that the auxiliary compressor just working with the small tank as designed, it in effect would try to move a much larger air volume to fill all the tanks and thus run too long. At the same time the system allowed air to leak back and push it out of level.

In addition, there was a crack in part of the compressor such that when operating it had to operate "extra" to make up for air loss. As I understand too, when the tanks were pressurized, some air could even leak out backwards thru cracks in the compressor filter bowl.

I hope this helps to: understand the functions of these tanks (these are not the same on all FTs, as I understand it), there are serious limitations on the time I can run the auxiliary compressor for the 2001, and there are check valves with the consequences of their failure being a leaning coach and even a coach that raised over time.

Alternative interpretations and clarification are welcome but if I understand MOT correctly, and my crawling around looking at things, I think I have it right, this report may help someone. Hopefully though you do not need this information!

Mike

Re: Leaning Coach, Air Check Valves

Reply #1 – September 22, 2012, 05:50:37 am

Interesting read Mike, and thanks for the info. In my case with my 2001 320, when I was headed to the Black Hills, SD,

I called HWH and requested an inspection on both the slide and leveling systems, the coach was driven onto a 6' high rack that you could very easy, walk under the coach, they sprayed the soapy mix on all air systems, found the rear leveling block had leaks and they repaired it. However they also showed me a few other non HWH leaks, the biggie was a cracked brass 1/4" Tee, they would not repair nor allow me to do it on their nice walk under rack.
HWH total bill was $196, was surprised, but pleased.

The Tee was replaced at Cummins @ Souix Falls, SD by a nice high speed skinny young guy.
No charge, but hefty tip

Also other leaks up front located on the box for steps, two regulators and one air solenoid showed much foaming, so replaced the two regulators and will do the solenoid when I have more time.
The end result: can not see anychange in the run time for the electric compressor, about 30 seconds every 4-5 hours.

Not sure I gained anything in the end, but peace of mind, thats important

Dave M

Re: Leaning Coach, Air Check Valves

Reply #2 – September 22, 2012, 09:05:49 am

There are lots of opportunities for air leaks in our coaches...try the air horns as an example of things to easily overlook....

Re: Leaning Coach, Air Check Valves

Reply #3 – September 22, 2012, 10:04:54 am

Dave, mine comes on every coupe days or every day max that I hear it anyway. If it is comming on every few hours you still have a leak. My last one that was hard to find was at the retarder.

Re: Leaning Coach, Air Check Valves

Reply #4 – September 22, 2012, 10:44:39 am

Thanks Steve, and John and Dave.

These are reportedly one-way valves that were to require or allow only one way flow of the air and were letting it go both directions, some thus made it back out of the tanks to leaks elsewhere and, the mystery part yet to me, put air back into the level (air bags) not needed, causing some to raise and thus tilt the coach. I really want to see these when we get the coach. I am concerned they too may have been the victim of the clay dust for the air drying system poor maintenance.

In all this though the HWH would show four red lights, saying it level as I understand it, but clearly it was not level (used a two foot long level on the kitchen floor, other places and looking from outside and doors coming open from cabinets). If I did crank and asked the HWH to re-level, then it would show one or two yellow lights, it would adjust that. Thirty minutes later it would even make another auto re-level. But over time the red lights only lit, no yellow, when clearly no longer level. Wish I could go to the folks Dave went to....maybe an excuse for a trip to that area of our Country. I think he was going to N. Dakota.

My auxiliary compressor was said in this to be $1700, so take good care it not burn out!!! Separately, I was told that there is another model, better due to size I think, of auxiliary compressor but they did not recommend that I needed that, just get this one going right.

I recall on the 2005 coach it ran seldom and briefly. Maybe three times per day, 20 seconds or so, when was all working normally.

On this one, I did crawl under (I KNOW I am not to do this) and sprayed a mix of water and kids bubble wand soap around and found a small leak where a drain valve line runs into the small air tank. Partly my doing I guess, for I had had MOT install drain valve lines from the tanks to the fender well that I could avoid crawling under to drain condensate.

Thanks to each of you, good to get your guidance and hear from you. I still have a meeting with MOT when Jackie and I pick up "Gus" and perhaps I can get better definitive info of the lean cause, etc. But since they installed the valves it has sat level three days and the pump not burned up, yet! Cheers, Mike

Re: Leaning Coach, Air Check Valves

Reply #5 – September 22, 2012, 11:38:28 am

Quote from: Michael & Jackie – September 22, 2012, 10:44:39 am

the mystery part yet to me, put air back into the level (air bags) not needed, causing some to raise and thus tilt the coach.

Mike,

That's one of the behaviors we had, and it was a raise solenoid valve not sealing due to debris (teflon tape) on the valve seat.

Photo upload - HWH leveling sixpack manifold

-sadly broken link-

Regarding the leaking between the tanks, in our '03 there's a check valve to protect the aux compressor (RN13526BR) and our small tank is isolated from the 2 large (A&B) tanks with a NC solenoid from HWH. This solenoid is operated by the "Air Tank" switch on the driver's panel. Switching it on links the tanks together, off should isolate them. We diagnosed the solenoid leaking by watching the A & B tank pressures on the Driver Info Center. Solenoid p/n I believe is RAP91775.

Quote

My auxiliary compressor was said in this to be $1700, so take good care it not burn out!!!

Yup, that's the Thomas TA-4101-DC pump's retail/Grainger price. You can get one from CFP Warehouse for $885 Thomas Compressor TA-4101-DC (12v DC) or watch eBay for one. Granted, an eBay purchase won't be warrantied like a pump purchased through MOT or FOT, but for $100-300 you can find a NIB spare (as we have). It may take a few months for one to show up for sale, though, and that doesn't do you any good if your pump is dying or dead now.

Here's to no more air leaks!

Michelle

Re: Leaning Coach, Air Check Valves

Reply #6 – September 22, 2012, 12:12:49 pm

Great info, will talk to MOT about that option. Mike Rodgers, on the phone, at one time was pretty sure that we had/have an internal solenoid leak. He said usually they leak outside and thus lower, but an internal leak could raise it. So from your reply, I need to ask them to be sure that not what going on. I wish I had your expertise......but I am a freshman, you are in senior graduate school.

I had some luck on this on the trip, Stewart Canty, salesman at MOT, stopped by one day at the park in NM. Told him the problem, he told me to try the air tank switch. Great idea, glad to have it. Well I looked and looked for the switch, excited to have another option. They either did not put those on the 2001 U320's or forgot mine!

Had a great time in NM, got to visit a couple of times with Brett and Diane. Met a woman who has a GV with motorcade number 7750. But of the few motorhomes in this small park (28 sites, great folks), friends of two years wanted to convert me from a leaning FT to a stable Allegro Bus, as did similar friends with a Fleetwood Discovery. A gas Bounder came in, an older Monaco, for couple of weeks but Montana fifth-wheels dominate this park. At one time though Dr. Cox and Duane were there so we had three FTs at one time for two weeks!

Cheers, have a blessed weekend. Mike

Re: Leaning Coach, Air Check Valves

Reply #7 – September 22, 2012, 11:22:03 pm

Michelle,
You mention Teflon tape and I laugh, just for grins, aircraft use,Teflon Is illegal due to most folks donot know how to install it so there is no strings of it. Like your had, in the fuel system, not healthy nor safe. Great stuff used correctly and in the correct places.

I have a spare air compressor that Igot from MOT, do not recall price but not a biggie..

Dave M
Hate posting from this IPad..

Re: Leaning Coach, Air Check Valves

Reply #8 – September 30, 2012, 08:06:53 pm

I posted elsewhere an admonition to newbies to be sure to on schedule change the air drier and filter system. So to follow up with the latest on the coach and lean, this is what MOT found.

The original problem I had with clay from the air system was that it contaminated not only the solenoids and a regulator but three check valves and left deposits such that air could now flow un-checked among all air tanks and even back to the auxiliary compressor (i.e. a leak). Thus the auxiliary compressor was trying to fill much more than the small front tank used for leveling and bladder control (hmmm).

The prior owner apparently did not maintain the air system. As the engine compressor runs compressed air thru the drier/filter and then into the tanks and this air also recirculates back to the system, the deteriorated desiccant media can turn to powder and place a clay particulate powder into the system. You do not want that. So change the filter and media on time.

Re: Leaning Coach, Air Check Valves

Reply #9 – September 30, 2012, 09:11:12 pm

Have tried to resolve and issue with the transmission engagement being affected by the slide. Adjustments were done atop the slide's locking pins and out at Oregon Motorcoach Center, a service facility for FT. Not successful, problems continued day one of road trip back east.

Mark Harvey @ FT, clued me in to the switch that would override the safety feature, so I got to FT with minimal problems. I did/but less frequently/ have to deflate bladder and reinflate, to get rid of the annoying alarm beep from dash.

Driving hard and learning this coach, I was not 'too' concerned about the list, until I understood the system and how things maybe 'should' work.

At FT factory the issue of compressor running (recently replaced) constantly!! ON/OFF!, ON/OFF. after leaving the shop day one, was a no brainer and Drew and an employee cut the power to it, as no fuse or switch had been installed by prior shop.

However, as absolutely GREAT I think these guys are here at FT, this problem has been looked at 3 times without resolution.

-Compressor now(after set up and adjustments have been checked) continues to cycle every 6 minutes(2000 times a week!+/-) for a few seconds.
-I can shut HWH system off, stopping cycling, but then coach does not stay level long......noticeable in a few hours.

I could not hang around any longer in nac. and heading back to Florida, after they said they fixed things again and again.

And 'Again', these guys are incredibly knowledgeable an efficient, but what's being missed? Any ideas?

The coach had been out in the NW for years so High Humidity was the norm.... Same problem? build up in lines??

thanks all, ron

Re: Leaning Coach, Air Check Valves

Reply #10 – September 30, 2012, 09:30:35 pm

Ron, will think on this a while. It seems in casual conversation and reading many threads that this air leveling system can develop problems, giving lean or running the auxiliary pump too long and risk burning it out. I imagine someone will have some ideas. I will try to think, reread what going on. At times I wonder if alternative leveling system might have advantages.

I cannot tell what FT did to think they fixed the leaning problem. I gather the aux pump ran too much, you got a way to shut it down and do but as a result the coach would lean. Sounds right. But FT must have done something else besides install a way to turn it off.....what am I missing, what did they really fix? Did they think they had it fixed or did you leave with it not fixed?

Separate, on slide, could be a failure of the locking pins to engage or the system to recognize that they did (that can happen....it is really ok but sensor not think so). Did they fix the slide alarm, the problem with transmission interconnect?

Any thought you have a slide bladder leak? I am sure they thought of that.

You can check for clay in the air lines by opening the wet tank drain valve, in front of the rear driver tire. You see water come out? You see "dust" or contaminated water?

Mike

Re: Leaning Coach, Air Check Valves

Reply #11 – October 01, 2012, 11:44:30 am

Michael,
The only way for air to go to a the air bags is through a travel solenoid or through a raise solenoid.
The travel solenoids are only powered open when in the travel mode.
The raise solenoids are powered open when you press a raise button or the computer sends a raise command.
I would check travel solenoids first.
With the end of the coach you want to check up and blocked ( but with weight on the bags so pressure in the bags is up ) take the line from the travel solenoid to the ride height control valve ( the two front ones T together at the ride height controll valve and the rear at each side ride height controll valves ) and disconnect it and put in in some soap solution to check for bubbles. On the front check both lines.
No bubbles, no leaks. If you find a leak change that solenoid valve.
If that doesn't find anything I would swap the raise solenoids (the bottom ones ) to see if the problem moves to the other side.
Remember to bleed down the air system to change any solenoid valves.

Re: Leaning Coach, Air Check Valves

Reply #12 – October 01, 2012, 11:59:50 am

John, thanks for your efforts here. I did not know that solenoids played no role in lowering the coach when in the Level mode. I take it that in the computer sends a raise command, you mean if I have it in the Level mode?

But I saw air pressure drop 25 psi on the dash gauges, hearing air being released from somewhere, it sounded like up front, and the coach went lower by an inch or so. I would have to look at my data, but my memory was that the front lowered in that event, not the entire coach. I can check though if it matters. Does that behavior indicate anything to you of what went on?

Mike Rodgers, when we were on the trip, told me that you can have internal solenoid leaks. Most are external and result in lowering but he has a few times seen internal which allow the air pressure to go to a bag and raise. I hope I referenced him correctly, my fault and not his if I got this wrong.

I really want to better understand this. Wish we had a class somewhere. Beyond that though, after MOT cleaned and changed out the check valves, the coach sat level for about five days before I took it home, where it is now and parked in Travel mode

Thanks again for your efforts, Mike

Re: Leaning Coach, Air Check Valves

Reply #13 – October 01, 2012, 12:38:08 pm

Michael,
I thought you had a problem with the coach going up.
All my reference was to that.
For air to get out of an air bag (other than plumbing leaks) it has to go out through a dump solenoid ( the middle ones) or again through a travel solenoid.
If you didn't find bubbles at the air lines from the travel solenoids as previously discussed then check for bubbles at the down solenoid vent on the manifold.
You may have more than one problem and that can make trouble shooting difficult.
Start checking for plumbing leaks then check the solenoid valves for leaks.
Fix one problem at a time until you get through it.
I found four problems when I went through the front system.
I don't think you want to be in travel mode when parked.
Remember when in the travel mode the travel solenoids are powered open and the ride height control valve controls to ride height not to level.

Re: Leaning Coach, Air Check Valves

Reply #14 – October 01, 2012, 06:27:00 pm

With the air gauges on the dash reading 132 psi, over time they decreased to 70 - 75 psi at which point I cranked to fill the tanks and avoid the auxilliary compressor having to fill to the 132 mark.

The coach would raise, seemingly on its own, for it would get out of level with the raising. The pump was disconnected. The coach would raise about an inch on driver side more than on the passenger side and create a lean. If you turn the key on the HWH would show that it was level when clearly it was not.

If you dumped the air, three wheel wells rested on the tires. Put into level mode. In 30 minutes it would auto level and do a good job. But then over the next 48 hours it would return to the unlevel situation

mike

Re: Leaning Coach, Air Check Valves

Reply #15 – October 01, 2012, 07:34:44 pm

When you turn the key on does it go into travel mode?
If it does you will loose all you level effort.
If after you level you leave it in the level mode will it keep it level for say 48 hrs?
Or after it levels turn the level system off (bottom left switch ?) then turn it on (press level switch once) every hour until you see an out of level indication.
That my help you narrow it down to what is the problem.
For air to go in or out of a bag it has to go through one of the solenoid valves.

Re: Leaning Coach, Air Check Valves

Reply #16 – October 01, 2012, 07:52:40 pm

Michael,
I should add that you can loose air due to the "O" rings under the solenoid valves.
One other long shot, when they make the manifold they drill a passage down through the top of the manifold. They plug that hole with a set screw.
On mine I had to loosen the two mounting bolts on the top to lower the manifold away from the frame mounting point so I could leak check that screw.
That's a last resort looking for a leak.

Re: Leaning Coach, Air Check Valves

Reply #17 – October 01, 2012, 08:04:20 pm

1. It does not go into travel mode IF I had left it in Level mode. It simply lights up the level mode status, usually four red lights unless I have not leveled it (i.e. usually when I turned it on the first time, one or two yellow lights were on, which it then corrected to get level). Remember - it would after leveling and becoming unlevel continue to show on the HWH level when it clearly was not level.

2. When I was having the problem, it would not stay level even though left in the Level mode. It would raise one or two corners, lower passenger front if it was not on the tire. It did not have the aux pump available (it disconnected). When it lowered the passenger front to the tire, you could often hear an exhausting of air.

3. I did turn the system off as you suggest and the problem continued as described.

4. Yes, it seems logical to me that solenoids are not only for raising.

5. I think it is solved. MOT found three defective check valves. That is what I was trying to communicate in this. IF someone has a problem similar to this, they may want to think in terms of the check valves, not only solenoids. I have heard now of two people saying they would try this next, it seemed our symptoms matched up. I had one expert tell me that there was not a check valve, then another told me to have line 57 checked (there was one there) and Michelle and Steve mentioned this too. Then I wanted to raise the possibility of an internal solenoid leak, that would lead to raising (versus a leak to the outside that would result in lowering).

I very much appreciate your trying to help. I hope it is fixed and I need do nothing more. I hope this helps someone understand the locations and roles of the check valves. Note that this is NOT the configuration in all coaches. There was an improvement, I am told, in later years.

If I am lacking in explaining what happened, how it behaved, how/why the check valves are to behave, and so forth, then let me know. Maybe a personal message or email if this thread is getting too long.

Cheers and thanks to all, Mike

Re: Leaning Coach, Air Check Valves

Reply #18 – October 02, 2012, 10:29:09 am

I realize that I overlooked responding to one comment, maybe not park in Travel mode.

I misspoke I imagine. I should have said that I store (not park) it in Travel mode. This is why....and I surely welcome alternative views......

I was told that when on a fairly level surface, when stored (not using it), travel mode is safer. If I left it in Level mode and an air leak developed, it would likely burn out the aux compressor as we would not be there to detect that and turn it off.

Re: Leaning Coach, Air Check Valves

Reply #19 – October 02, 2012, 05:55:06 pm

I agree with Mike. Once I have my coach in a level status, I turn the level system off. It stays that way for weeks and weeks.

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