The 1975 MCI 5B I bought is not getting air to the air pressure gauge, warning light, wipers, or door lock, but apparently everywhere else. Ive been trying to find a manual or an air system schematic, and will contact MCI about manuals if I cant locate any anywhere else, but thats not going to help me today.
Heres where im at. I put air into the accessory tank, the tank under the driver in the front left mechanical bay, and pressurised the system to approx 120 psi. The Bus aired up fully, the emergency brake valve released, the brakes apply and release, I have air to the various gizmos at the engine, belt tensioners and tensioner valves, etc., air at the ping tank schrader.
However, when I flip the master switch to on, along with the other idiot lights that come on I get the low pressure warning light, the air pressure gauge in the dash panel isnt moving, the door air locking lock lever does nothing, and neither do the wiper controls, no hissing air, nothing at all.
I found a MCI 9 manual online and looked at the air system schematic, but didnt see anything. I am wondering if there is some electric control valve that opens with the master switch on that allows air to reach the dash panel. Any ideas??
First, get the 3 manuals for the coach, Parts, Maintenance and Operators.
The air gauge is mechanical, so nothing fancy there.
Are you using the emergency fill or into the accessory tank directly? They are both under the driver.
All of the things you listed are fed from the aux tank, so I think you are connected to the other, so filling some of the brake system, the parking tank in particular.
If you want to fill the system in a more traditional manner, install fittings into the discharge muffler drain in the curb side engine access door, where it says "drain daily".
Did I mention get some manuals?
happy coaching!
buswarrior
Okay, I probably spoke too soon. Its looking like filling from the front aux tank im running into check valves upstream. Im going to leave the air alone and focus on getting the engine running, theres probably nothing wrong.
you need to do like BW said and fill from the rear access door at the discharge muffler. I believe by doing so the air will also go through the dryer (if you have one) so as not to introduce wet air to the system.
Quote from: thomasinnv on April 04, 2011, 09:39:38 AM
you need to do like BW said and fill from the rear access door at the discharge muffler.
That is more than likely the case. I just spoke to a guy at a Bus shop. While he didnt have a book in front of him, between picking his brain and my own, I believe there are check valves down stream and im filling it from the wrong end.
I've never tried filling my MC-5 from the front. But I fill it all the time from the back using shop air or on board air compressor. Works great. My 5A doesn't have a dryer, but i installed an air fitting on the ping tank ahead of the wet tank. The gauge comes up, all accessories work and the brakes can be made to release. Its just like running the engine.
Fred
I know the brakes and suspension work, which were the main things I wanted to know about the air system, and now that I know I was filling it at the wrong end, I can remedy that if need be. But its time to go try and get her going, and thats tomorrow. Im heading out after I have breakfast. Got the trees along the driveway cut back and graded the bottom a bit, got a Coach net policy I hope I wont need, got to put belts back on the alternator, fix a hose, prime the fuel, and then....
With some help from above I could be headed home Thursday or Friday. I really dont think I want to start out driving at night. Though im not sure why not if its running okay. Roads will be much quieter, cooler temps. We'll see.
Sounds like you were just filling the front half (commonly referred to as the accessory side)
Filling it from the rear will solve all that.
Good luck and have fun.
Just remember that sometimes things go bump in the middle of the night !
;D BK ;D
Don't go out at night unless ALL the lighting is working properly, or you are a BIG target for a pull over.
happy coaching!
buswarrior
Quote from: buswarrior on April 05, 2011, 07:59:25 PM
Don't go out at night unless ALL the lighting is working properly, or you are a BIG target for a pull over.
happy coaching!
buswarrior
BW we just ran the Vandy to Ft. Walton Beach run again this yr and all 3 coaches had all lights working when we left. But one had a taillight out, 1 had the top 3 center clearance lights out and one have the right rear clearance light out (we noticed all this while we loading!)
But one of the drivers said these kids have enough booze and "stuff to light" there shouldn't be any worries! LOL!
;D BK ;D
Quote from: Busted Knuckle on April 05, 2011, 07:57:03 PM
Good luck and have fun.
Just remember that sometimes things go bump in the middle of the night !
;D BK ;D
Fun? Thats the part im really looking forward to. The wife too. She is so tired of bouncing and yelling to be heard, the thought of something smoother and quieter has her excited to see it happen.
Bump in the night? Its got a hitch that looked beefy enough, so ill be dragin the Jeep behind for spare wheels. The traffic around Little Rock has not been fun the few times I been down there, missing all that wouldnt bother me at all.
Thanks again, BK, and everyone else, y'all been a lot of help.
Quote from: buswarrior on April 05, 2011, 07:59:25 PM
Don't go out at night unless ALL the lighting is working properly, or you are a BIG target for a pull over.
happy coaching!
buswarrior
Copy that. I know one in the back was out, ill make sure I have em all burnin.
And again, thanks a lot.
Just to follow up. I tried the schrader at the Ping tank, there is some blockage ill have to look at but it wouldnt take air. Just made a slow gurgling noise. I unhooked the drain line and screwed my air hose to that fitting, and that worked. This guys compressor is only building 90 PSI and I cant quite reach 90 on the guage, but low air warning light keeps flasing. Dash gauge works, wipers work, door lock is INOP. No major leaks, just a little hissing around the belt tension cylinders. All the lights work except one front inner clearance light, and the right side center roof clearance light. No emergency flashers, but turn signals work. Maybe just a flasher??
I have a sprayer pump, tomorrow ill rig it and figure out how to prime it.
There is a drain valve on the bottom of the ping tank, and the tank itself is just a hollow pipe. Take the drain valve off and scrape out the congealed muck. I replaced the schrader valve with a female quick-connect air fitting and a shut-off valve, and I connect it to my air hose with a male-male adaptor.
Brian
Thanks for the great idea Brian, I'll have to try that. I think I'll blow down the air a few times through the drains to see if any gook or water comes out.
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
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.
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...
Paul,
Do you think you will be bringing her home in the next few days?
Rick
Quote from: Rick59-4104 on April 07, 2011, 08:33:41 PM
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.
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.