Newby, really uneducated.

[Rayj1954]

My wife and I have a gospel ministry, one of our friends was unbelievably kind and made us a deal we couldn't refuse. So now we have a 84 MCI MC9, when we picked it up I could hear air leaks in the dash and when you shutdown the engine it leaked down super fast. It came home just fine, the compressor over came the leaks held 120 lbs. Then I read on utube airing up the system with an oil less compressor.  Hooked in in the passenger side door where the tag axle valves are.  Compressor was not strong enough to overcome the leaks.  So I started the engine to close the door and quit for the day. Now the onboard compressor will not air up at all.  Please someone give me pointers. No manual came with it and the pictures I can find online are so degraded I read the words, and the diagrams about the same.  Hopefully I have not destroyed the onboard compressor.   The education begins.  Thanks in advance.

[Busn-Gramps]

Hi Ray, did you close the valve where you hooked up the portable compressor ? just a thought.

[Rayj1954]

Yep that valve I did.  Going to try a larger compressor this week end.  Got to move the Whale before bad weather hits here.  Thanks.

[Geoff]

It sounds like the unloader is stuck open in the bus compressor. 

[Ed Hackenbruch]

Check the line going to your air gauge. I could hear and feel air leaking under my dash but couldn't tell what exactly was leaking until i took the dash out. It will probably be that or the air wipers if you have them....can't think of any other air lines under the dash.

[Branderson]

Check the line going to your air gauge. I could hear and feel air leaking under my dash but couldn't tell what exactly was leaking until i took the dash out. It will probably be that or the air wipers if you have them....can't think of any other air lines under the dash.

Yea that sounds like it must be one of those two if you can hear it under the dash.  If there is a leak in the wiper line, would it really cause it to drop air that fast? 

[neoneddy]

First, welcome!  Second I was in your shoes last spring, everything worried me, still does, but I've learned what more what is normal.

More seasoned bus nuts please correct me if I'm out of line here.

My bus takes a good 4-6 minutes to air up from 2-3+ days shut down,   I can dramatically reduce that time by hooking up my home compressor through the port you're taking about.

I only have a 6gal pancake compressor, if I let it work on it WITHOUT the engine on it will build pressure up to about 60 PSI, then it's slow going after that and I don't want to burn out the motor on the compressor.  It's just not made for 100% duty cycle.

If you can track down all the leaks it will work,  eventually, but it can be like chasing your tail.   The compressors on the bus are pretty beefy and can easily keep up with the leaks you have.   When I bought my bus there was a 1/4 hole in a copper line in the tunnel, it still aired up eventually, it's a beast.

https://www.youtube.com/watch?v=wOKKGaRRp_w    Here is one of my first videos,   In the middle someplace I  was  noticing all the air leaks and messing with them.  Next few videos I was doing similar things.

So long as you're tanks are building pressure, cycling normally (going from 120 to 90 to 120 to 90....), draining (water)  them regularly, just roll with it.   Put away money for new air bags , engine work, etc.     I have a neighbor who drives buses for the City , he said they all leak.

[eagle19952]

if the air dryer is frozen or clogged up...the unloader will think the system is at pressure. And go into bypass ie: stuck open, which open is what it does when the governor tells it to..

[lvmci]

Hi, is the dial for the wipers all the way on or off, clockwise or counter clockwise? Otherwise air might escape in the park or middle position, lvmci...

[chessie4905]

Go to a Napa, Auto Zone, Pep Boys, Advance Auto, etc. Pick up a mechanics stethoscope. Remove the metal probe so you just have the tube end. Use it under dash to trace the location of leak/s. Take your time to locate exact spot. Verify with soapy water sprayed or sponged to suspected small leaks. This item is indespenciple in future for finding or locating noises or leaks. Not that expensive. Cheaper would be a 2 foot piece of 3/8 th hose, but not as sensitive.

[robertglines1]

if you have air in system. Forget aux compressor.  Bleed it down to 0  by pumping brakes engine off. then start engine and see if the engine air compressor will build up.. Don't depend on aux compressor for driving.  Air leaks on air wiper are common play with wiper control it may stop.. lmci sounds like he has hands on with problem.. research air brake test. use ears and soapy water  1/4 cup dawn   mixed with water in spray bottle .look back in few minutes and you might see bubbles that did not appear at first shot.

[Rayj1954]

Thank all of you.  I have a at least a weeks work chasing the pointers.  Oh btw don't want to use the aux to drive. Just have the system loaded when I start engine.

[Geoff]

Your first post said your "onboard" air compressor quit working.  What happened to that major problem?

Did you mean the engine driven air compressor? 

[Rayj1954]

Still trying to find that.  It got quite cold here and I am in recovery from spine surgery so things quickly got really slow.......  I haven’t gotten to go on the hunt yet and my stepson is certainly not as interested in finding the problem as I am.........     and yes the engine driven compressor.  This coach has folding doors that are air operated and I wanted to be able to air up the system so the doors would open.   It all worked just fine until I tried the external compressor.

[John316]

Ray,

Welcome aboard. Sounds like you have your work cut out for you. Good times ahead. What is the name of your group? And where are you located?

Do you know any background on the bus? Did another group use it, etc?

Blessings,

John