Air Bags - MCI-DL3-45 Chapter 3. The lean.

[plyonsMC9]

So the saga continues.  All the airbags have been replaced.  All leaks fixed except minor one from the front LH, the sleeve heading to the airbag.  That leak will be fixed tomorrow a.m.  All leveling valves, including check valves, replaced.  The original_heavy_ lean to the LH side however, remains an issue. 

Side note, the heavy 2x12 ramps we built are a huge help!

We have air pressure to both sets of valves (LH & RH Rear), BUT the airbags on the LH side are not gaining any significant air pressure.  I'm bamboozled.  Interior guagues show 120 lbs.  RH side air bags have plenty of pressure. 

This bus does have a manual air leveling system I'm guessing added by Vantare, back when it was converted originally.  But it's when the bus cuts over to the over-the-road setting that the lean shows up. 

Any suggestions of what to look for?  Learning a heck of a lot in this 'adventure'. 

Thank you and kind regards, Phil

[lovetofix]

First thing I would do is put it in over the road mode with the bus aired up. Then disconnect the LH leveling valve control arm from the axle linkage. Pushing up on the control arm should inflate the bags on that side. If they do not inflate remove the line going from the leveling valve to the air bags where it enters the airbag. Make sure it is supplying air at full pressure when you push the control arm up.

For manual leveling to work, you need a shutoff valve between the leveling valve and air bags to prevent the leveling valve from exhausting the air you are manually adding when raising  that corner of the coach. I suspect this valve has failed in the manual position or lost its control wiring. This will not allow any air to reach the airbags from the over the road leveling valve but leaves the manual system functioning as it should.
It is safest to do this all after removing the LH set of drive tires.

[plyonsMC9]

Thanks very much 'lovetofix'  !

Have gotten a lot of experience now in taking off those tires.  Great suggestion, I will continue to update the thread after checking this out.

With best regards, Phil

[richard5933]

A few years ago I had my GM 4108 at Luke's shop. It was up over the pit for some routine maintenance, and I asked Bill to tweak the ride height adjustment. Quite easy to do when the bus is over a pit like that, as it could be dropped all the way down to the bumpers with little risk to us.

When I take it in for service in Wisconsin, the shop uses wheel lifts on all four corners to accomplish basically the same thing.

Any way you can simulate a setup like that while you work on the bus? Any truck stops near you with a pit that you can rent for a while?

[buswarrior]

I'd be looking for the manual control system not properly switching to auto ride height.

Somewhere, something is putting air, or not putting air, where it is supposed to go.

How many people have been touching this bus's underpanties, since it worked correctly, and have messed something up?

It will be a lovely thing to have it working correctly.

Happy coaching!
Buswarrior

[RichardEntrekin]

Read the first three pages of https://www.hwhcorp.com/ml20635.pdf to supplement what Fixit explained to you on how the systems typically work. Yours may NOt be exactly like this but it will likely be something similar.

The KEY to understanding a system like this is that the air from the leveling valve goes through a electrically operated valve BEFORE it reaches the airbag. Many assume just the opposite which wreaks havoc on the troubleshooting when having the wrong model in your head.

[plyonsMC9]

[quote author=richard5933 link=topic=35521.msg409986#msg409986 date=1623107254
When I take it in for service in Wisconsin, the shop uses wheel lifts on all four corners to accomplish basically the same thing.

Any way you can simulate a setup like that while you work on the bus? Any truck stops near you with a pit that you can rent for a while?
[/quote]

Thanks Richard!!  I do appreciate the safety notes (Job #1) and we are working on that now.  I thought I was set to go when the ramps were in place.  Now with wheel removal - not so much.  Did get a couple of 22 ton jack stands - good price @ Home Depot.  And more wheel chocks.  Still a work in progress though.. 

Kind Regards, Phil

[plyonsMC9]

I'd be looking for the manual control system not properly switching to auto ride height.
<snip>
It will be a lovely thing to have it working correctly.

Happy coaching!
Buswarrior

Yes, it would! 

And - just received a status change yesterday.  I called the guys at C&J Bus Repair (new BCM Advertiser!) and after a couple of minutes on the phone w/ the shop foreman, he sez to me, "wait - you have the MCI RV Air Leveling system - a factory option".  What?  A couple months ago I had called MCI & they didn't want to touch it because it was some after-market "thing".  When I call MCI back and use those exact same words to describe it, the tech sez "Sure, I have those docs for you".   Which goes to show, wording is really important.  And I'm still learning.  Unfortunately, later working w/ another tech who actually worked on that system, I heard that what I have was only one of about 6 that were ever produced.  He also said something about a "mess" that I couldn't quite make out.   

But now, we have at least some of the docs, and they are quite helpful.

More to follow, thanks all!,
Phil

[ktmossman]

I was going to ask about that...  I wasn't sure if something existed that early, but I know that by 2006, MCI had a valve mechanism that specifically controlled left/right leveling.  My MCI guy recommended regular use of the air system because, if that valve gets stuck, it's apparently fairly pricey.  I wonder if yours is an early version of it.