Air bag problem 1981 MC9 with air beams.

[bottomacher]

My left side airbags won't inflate after being parked for several months. I hit the maintenance manual right away, but the print on my air system schematic is so tiny and blurred that I can't read it even with a magnifier. When I air up the bus with shop air, I can hear something that almost sounds like a small motor running in the area of the center of the bulkhead forward of the rear axle, but it doesn't sound like an air leak (to me).I have ramps and will get under to look, but recent knee surgery makes it very hard, and I'd like to try to figure out what's wrong so I don't have to make so many trips on the creeper. Is there an air relay valve that may be bad? Front and rear bags are down. It's a California bus, and there is no apparent rust problem with the air beams. Thanks in advance for your help.
Don

[bevans6]

The front air bags are interconnected, so if one side is up, both are probably OK.  All side to side levelling comes from the rear air bags, so if one side is down it will tip over to that side both front and rear.  The suspension is filled from the auxilary system, so if you are getting full air pressure I would look at the levelling valve first, see if it is getting air to it, see if air is being delivered to the air beam, see if the little lever is still connected to it's push-rod, all of that.  Once you get under there, it will probably be pretty obvious what's not working.

Brian

[fe2_o3]

Where you at? There might be some one close with better knees that could help locate the problem...Cable

[bottomacher]

Thanks to both of you for the reply. I'm about 35 miles SW of Atlanta, next door to Peachtree City. I have never found a bus mechanic around here, and this knee situation will get worse before it gets better. I can't get it up on the ramps until early next month. I was trying to buy the likely parts before I go under the bus so I could do it in one or two trips.
My first thought was the leveling valve, but I have never opened one up and didn't know how tempermental they are. That sound also threw me, but my hearing is about as good as my legs. I have three new valves around here somewhere, but I'm not sure if they are the same model as the MC9. I'll examine one to see if I can figure out what to look for. Thanks again.

[Frank @ TX]

Hi Bottomacher,
I have an MC9 also.
The tanks and plumbing between them make strange and different noises.
Most likely you just have a bad left rear leveling valve , once it's fixed all will be good.
Have a good time and get busin'.
Frank

[bevans6]

I have a real hard time getting the bus up  high enough to work under it.  Some probably think it's more work, but I just take the wheels off the side I need to work on.  It's the fastest and simplest for me.  I jack up the body, get it nice and high, get some blocking in there, then I jack up the axle, pop the wheels off and I can get right in there

Brian