4104 Air Bag Leak

[gus]

I just replaced my RR airbags and leveling valve plus added air chamber blocking plates.

The bags leak down after 6-9 hrs.

I've gone over them two times with soapy water and tightened all the bag hold down nut two times, each time took some small tightening, but not much. No change?

It is no easy feat to even see all the circumference of the bags so it is possible I may have missed some small sections. I used tons of soapy water and a strong light.

The frustrating part is that the old bags did the same thing but in less time. I found that the old valve leaked a very small amount so was convinced that was the main problem. I'm no better off after all those $$ and tons of hard work.

There is obviously a small leak between the new leveling valve and the bags since there is a check valve in the LV. I've checked the LV discharge port for leaks and found none. I've checked all the air supply connections from the valve to the bags.

The left side still has the original setup with air chambers and it stays up for three or four days!! Frustrating!

I'm about out of ideas!! All are welcome.

[artvonne]

  Not that I know a darn thing (okay maybe a lil), but wouldnt an air chamber on one side, and not on the other, make it ride funny?? Soft on one side, hard on the other?? Is your intention to block of the other side as well??

  As to the leak, can you block the airline going into the air bags themselves? See if it holds, then work your way upstream?

[fe2_o3]

     Does the rest of the coach air fall off at the same rate, or is it still aired up? Is it trying to level it self and running out of air? Is the check valve leaking? Is it on a level surface? Does the leveling valve need adjusting? Line fittings all tight? New lines leaking? Sorry no answers. Only questions.
   Played this game with mine a few years ago. Frustrating...Cable

[Kevin]

Heya Gus,

No answers for you, sorry. I also have an '04. Mine too leaks down on the passenger side, but front. Takes a bit longer than yours, usually a matter of a few days. If we are camping in 'er and consequently bouncing in and out of the coach fairly often, she'll settle down dang near overnight.

My solution (after spending considerable time below with a soapy water bottle, to no avail) is to use (and don't anyone dare ridicule me!!!) an old scissor jack from a... well, a... shoot, ...a, um... ahem.... okay, damnit, a 1980 Datsun 210 wagon that me dear ol' mum bought brand new (sniff) for a stand under the passenger side right strut rod pivot. This is placed after manually leveling the bus on blocks, and obviously prior to all the air dribbling out. 

It works great. I fire up the beast when it's time to leave a week later or so, let the air pressure build to 120 psi and crank the puny little buggar down. The leveling valves take over and it only takes minimal effort for the first couple "unwindings" of the jack crank 'til we're free and ready to roll. Well, now you know. Hey, one stinkin' ancient bus thang at a time, folks!!! Right?! 


Cheers!

[Rick59-4104]

 Gus,
You may have done this but can you see the backside of the airbags with a flashlight and a mirror? Mine had a leak on the front right rear airbag and the bus would settle on the right side(front and rear).

I had the back 4 bags replaced at a shop in Branson, the next morning 2 of the bags were leaking where the rubber meets the plate on the top of the bags., took the bus back to the shop, they licked the calf again...now over a few days they leak down a few inches but not all the way down on both sides front and rear of the bus (a little more on the curb side). The shop is saying I may need the block off plates, I need to find time to  pull on some blocks and crawl under with a squirt bottle. The first leak I had required a mirror and light to see as it was where you could not see that part of the airbag. It sounds like this is a common problem.
I know what you mean about the time and money and frustration when they still leak.

Rick

[Len Silva]

When I had my 4104 and chasing down air bag leaks, I pulled the tubing to each air beam and replaced it with a schrader valve.  I inflated each to about 60 psi and left them alone.  In my case, they all stayed up indefinitely leading to bad leveling valves as the problem.  There was no apparent leakage at the vales, but I guess they let air back into the system.

I was fortunate to have a pit to work in.

[robertglines1]

observation..you are dealing with 2 different volumes of air available to air bags  on side the air bag is the total volume of the air bag the other has storage volume(air beams) with several times the capacity of the other..so if they leaked equal amounts the one with the larger volume has much more available to leak out..one with less volume would be calling for air sooner(from the leveling valve) so ...

[robertglines1]

possible solution to volume difference..put a small tank between the level valve and bags on side with block off plate..like the portable air tanks..Bob

[gus]

Thanks for all the responses;

Art,

There is absolutely no difference in ride in the bus with one side blocked?? This is against all logic but a bunch of nuts posted this fact long before I installed mine and they are correct, I can't tell any difference at all except that it airs up in 1/4 the time! As two of you have suggested, I will disconnect the line to the bags and air it up there. I didn't consider this because the leveling valve is new but it may be leaking.

Cable,

No. Yes. Don't know. Yes. don't know. Yes. No.

Kevin,

There is no passenger side in front, both front sides are hooked together and can't leak one at a time. If one side is down it is the rear leaking. The rear valves determine bus leveling side to side. By placing a jack on the right front you are twisting the body. On my 4104 this causes the front door alignment to change. Any block should be on the rear at the rubber bumper but that is he** to get to and dangerous.

If you mean you jack at the rod attaching base that should be ok. However, I wouldn't have the guts to jack at the front radius rod end because it is designed for horizontal force, not vertical. The rear is even worse because it is so heavy. This also has to put a tremendous strain on the rubber bushing. 

Len,

I'm going to do that even though my valve is new. John vickers said that sometimes a flake of rust or dirt will jam the check valve open and let air out. That is probably the reason the supply and bag lines are supposed to have filters!! Mine had one but now has none.

A pit is nice, I need to remove both rear wheels to really see what I'm doing and haven't done that yet.

Robert,

I thought about this for a while and I'm sure you're correct about the time difference, but I don't think it would be as much as 9 hrs vs three days,  Pressure holds up the bus, not volume.  When bags and a beam are down you are just left with more air at the same too low pressure. In any case, neither system is supposed to leak down for at least a week, and mine did so when I first got it.

Thanks also to John Vickers who called yesterday with some good ideas.

It is very interesting that the leak now is almost the exact same as it was before the new bags and new valve??

Please keep the ideas coming.

[Kevin]

Hi Gus,

I'm pretty ignorant as to how the leveling system works. If I'd have know what you know, I wouldn't have wasted all that time under the passenger side front with a squirt bottle! It's no wonder I didn't find any air leaks...

Been placing the jack (more just a support really, because I don't actually lift with it) under the end of the radius rod, sure enough. Never really considered that it could ever do it any harm... bloody thing is monstrous, but I suppose you're right. As the air gradually leaks out, all the weight on that corner of the coach would be resting on the rubber bushing. Hmmm, just walked out and peeked under her skirt. In future, I can certainly relocate it a few inches forward onto the bracket instead, as you mentioned.

I had become somewhat frustrated with my efforts in trying to find the leak (in fact, I haven't even bothered looking for the past few years) only now, dangerously armed with this new knowledge, I believe I'll have a look at her rear end.

Thanks for the information, and best of luck pinpointing your problem. This board and you folks are great!

[gus]

Kevin,

You really don't want to block the front at all because leaking rear air bags on one rear side  will make the body twist, it needs to be blocked at the rear but that is a whole new problem.

I didn't know this stuff before I got my 4104 and read the manual either, welcome to the club of learners!!

The best rear block is between the suspension parts where the air bags are located. It is not good to block the body because it might be weak from corrosion and there is a lot of weight back there. So,  the problem is getting under the bus to insert the blocks, a real pain and kind of dangerous. It would be nice to be able to block it by reaching over the duals but I haven't figured out how to do that yet, my arms are about a foot too short!! I can reach the front, but not the back.

Since we're leaving tomorrow on a 1300 mi trip my solution until I find my leak will be to park on an incline. When it leaks down the bus is level. I did this in my son's driveway in WA and it worked fine!!

[Rick59-4104]

Gus,
Good luck on your trip and thanks for the information and help on my 4104. I have a hard copy of the maint. manual for the coach on the way, I am looking forward to reading it.

Rick

[fe2_o3]

  Where are you headed? 1300 mi. is a fair trip. Maybe the bags will settle...Cable

[Kevin]

Hi Gus,

Any further developments in locating your air leak? Just curious. Also, I've taken heed of your advice regarding blocking rear as opposed to front. I see what you mean about difficult access. I will eventually get to looking at the rear valves and hopefully find my problem.

Never had any noticeable body twist with mine, but I also (didn't mention it previously) blocked the rear in the same manner... under the radius rod. Again, never gave a second thought to bushing damage, but I'm sure it wasn't helping things any!

I, too, have parked the coach on an incline anticipating the right side settling down. Usually (in my case) because I was too tired or lazy to block 'er up on the stands. Mine settles down a bit slower than yours, it seems, so we'd tolerate leaning to port for a day or two - and then gradually settle down more-or-less level.

Well, let us know if you've had any luck with yours. Like the burgundy paint scheme by the way. Looks nice! Ours is blue.

Cheers!
Kev

[gus]

Kevin,

I haven't done any work on the bags because my sudden huge engine front main seal is causing me to lose so much oil I have to stop that first.

We went to northern IL on our trip and parked the bus on an incline. Weird thing is that the right side never went down to level the bus, after two days both went down at the same time?? At WalMart parking lots the right went down in just a few hours? When I got home and parked it level the right went down overnight? This thing is weird.

The trim is red, it is very close to the original Trailways color which makes me happy. The only thing I don't like is the wide dark gray stripe at the windows, that should be bright Al like the rest. The side that looks burgundy is in the shade, note the front looks almost bright red.