MCI air system

[bevans6]

Basically the ping tank is there to catch the crap that  comes out of the compressor first, and it has a sign on it "drain daily".  If you open it when there is pressure (if you turned the bus off while the compressor was on a fill cycle) it sprays oily water in your face, so be careful...

Once you get pressured up, drain the tanks in this order.  it's OK but not optimal to get water and a little oily junk out of the wet tank if it hasn't been drained in a long time.  That's it's only real function - to condense water out of the hot air from the compressor that the air dryer didn't catch.  it's quite bad to get a lot of water out of the other tanks, but weather conditions can sometimes get some small condensate in them. 

Wet tank - drivers side of the pair of tanks on the rear wall of the front axle bay.  all the other tanks should hold pressure.
Accessory tank - under the driver's seat.  All the other tanks should hold pressure, but the dry/service tank should go down to around 60 psi if the pressure protection valve is working.
Dry tank - behind the driver's side wall of the rear luggage bay, there is a little door near the floor on the rear wall, open the door, little twist valve.  It should have held some pressure when you drained the accessory tank.
finally, drain the parking/emergency tank.  it should have full pressure at this point.  It is protected by check valves from all the other tanks.  It is the passenger side tank on the rear wall of the front axle bay.

It's possible to put cable operated drain valves on the two tanks in the front axle bay and run the cables into the fuel filler area.

There is a air dryer located on the front wall of the front axle bay, most probably.

The simplified flow is compressor to ping tank to air dryer (with a line back to the air governor to tell the air dryer when to purge) to wet tank through a check valve, to dry tank through a check valve.  the dry tank, also known as the service tank, feeds the brakes.  From the dry tank air flows throught the PPV, a filter, and splits into two directions.  It flows into the parking emergency tank via a check valve.  This tank serves the parking brake and emergency functions of the DD3 rear brakes.  The air also goes off to the accessory tank, not through a check valve.  The accessory tank services everything other than brakes on the bus that uses air - all the air cylinders at the engine, the door, the wipers, the suspension, etc.

so there are a number of check valves.  By draining the tanks in the correct order, you can check the operation of the check valves and the pressure protection valve.

Brian

[thomasinnv]

for the door airlock to work, the master switch on the dash needs to be on, the over-ride switch needs to be off (little lever under the dash right side of the steering column with red knob on the end...pull it toward you) and shut the door. when you shut the door give the door handle a little push toward the window and it should "click".  then if all is well, the airlock should engage, but all those steps have to be done for it to work.

[artvonne]

  The rod to the door is gone, the handle has light spring pressure holding it in the closed position, but it does not go any farther. I also dont hear any air when I move the lever with the red handle, im thinking its been bypassed. I levered the latch over with a screw driver, seems like there is a slight spring inside, but no air. I'll mess with it after I get home. Unless...is there a switch on the door itself that I havnt seen? 

  Im just north of the Little Rock AFB. A real treat watching C-130s coming in all day, many in steep banks cranking in to line up with the runway. Even saw a C5A today. Man thats a BIG bird...

 

[Rick59-4104]

 Paul,
Do you think you will be bringing her home in the next few days?

Rick

[artvonne]

Paul,
Do you think you will be bringing her home in the next few days?

Rick

   Hey Rick~

   I'm hoping to head out Friday/today. I want to swap a couple tires around and play with the Genny, after that I want to point it for home. Say a prayer I make it up my driveway. The Lord knows ive said enough of my own and done the math, now I gotta have Faith. But a few more prayers cant hurt.

   Anyway, if running them hard makes them run good, it should be running pretty good by the time I have to test it. All those short grades along I540 should give it quite a little workout.

[artvonne]

  Well, Da Bus is sitting 50 miles from home with a blown tire. I didnt like the looks of the fronts, so before I drove out of North Little Rock I swapped them for with the outside rear duals. Boy did that kick my butt changing 4 wheels. I told my wife that if I did that once every day I would really be in shape.

  Anyway, I was stopping at rest areas and feeling them, whacking them etc., they were staying cool and hard. But I hadnt stopped in about 50 or 60 miles when the tire blew. I walked back and found it hanging loose on the rim, confirming it was actually a tire that blew and not something important. It was a pretty spectacular explosion. But it was getting dark, and without the alternator I figured that was far enough. I limped into a Truck Stop and parked it and noticed the lights were getting dim, good time for a flat. I was going to get it home today, but its 87 degrees and im tired. It can sit til tomorrow. And honestly, I didnt realise how dog tired I was until I stopped. Driving home in the Jeep I was actually glad that tire blew.

  But man, she ran really great. I had to get used to the steering, and wisely chose to take the frontage road out of the place rather than jump right onto the freeway. Nothing like a bad two lane black top road to teach you how a drive a Bus. I drove down about 8 miles getting the feel of it, watching the exhaust, looking for trouble, and then stopped to give it a quick walkaround before hitting the freeway. Shifting was much easier than I envisioned, and except for a few screw ups I did okay. My biggest problem is not waiting long enough between third and fourth, I would get a grind from being to early. I would liken the feel of it to a Mercedes diesel. The engines back there, and you can feel it and hear it, its got mechanical feel that goes through the Bus. Once I stopped chasing the steering and just flowed with it, it steered just fine, even with the strong crosswinds she just tracked straight and true.

  There was a blue tinge to the exhaust, you could see a faint haze behind for about the first 30 miles which got fainter and fainter and then she burned clear. The power got stronger as I went, about 50 miles out I was pulling out of a Truck Stop, she really wanted to go. And its probably got the highway gears. I didnt check with the GPS, but the speedo kept going past 70 and id have to back it down. It took grades far better than the Bounder, few pulled me down below 65, and it wasnt til I was almost to the tunnel I hit a long grade that forced me down into third. The Compressor picked up too. By the time I was around Little Rock I would see the air slowly bleed down to just over 100 psi, then quickly climb just past 120.

  So thats what I did yesterday. The hardest part was pulling out of that lot onto the road. Up until then I kept wondering how stupid I was for buying it, etc., etc.. This probably sounds funny, but I felt like a kid driving my first new car. Laying awake for nights unable to sleep, working out all the things that could go wrong, now multiplied a million times with the complexity of a Bus ive never seen move, and 50 years of experience in things going wrong. Boy how it all evaporated as the miles unrolled beneath the windshield. Now I have to start a list of things to check, fix and/or rebuild. First one is some decent tires and some aluminum rims. And a wash, polish and engine clean. And change oil and filters and run the rack and paint and clean and paint and clean and..... I'm gonna be buzy a while.

  I want to thank everyone here, I dont think I would ever have done this if I hadnt found this Forum, probably would have just sat on the fence. The advice and guidance, as well as the discouragement with poor choices, were all appreciated.