Hi all
Headed east on I70 dropping down out of the Eisenhower tunnel I look down and my air pressure says 30lbs and dropping. found a wide spot quick and thank heavens for spring brakes. I took a walk around the bus and can't hear any air leaks and no bad sounds from the air compressor. I replaced the governor on the compressor about a 1.5 years ago and has been working fine.
Ideas???
Sitting on I-70
--Mike
1st step is find out if the compressor is turning you can tell that by listening to the intake be it a filter or hose,no intake no compressed air for sure
Quote from: FolkBus on September 17, 2015, 11:07:51 AM
Hi all
Headed east on I70 dropping down out of the Eisenhower tunnel I look down and my air pressure says 30lbs and dropping. found a wide spot quick and thank heavens for spring brakes. I took a walk around the bus and can't hear any air leaks and no bad sounds from the air compressor. I replaced the governor on the compressor about a 1.5 years ago and has been working fine.
Ideas???
Sitting on I-70
--Mike
Hi Mike, I'm about 45 minutes away. What can I do to help ? I have tools, not a lot of knowlege but have been around. Give me a call anyway. 303-513-nine042
Hi all
Here is an update. I seem to have a leak near one of the valves (or is a valve) at the rear axle (MC5A). I went and picked up a small compressor so I could put air on the system (teach me to leave the small one at home) I can hear air leaking but can't find the source. If I try to listen for it with the motor running to much noise, so I'm still not completely sure about the compressor, although right now I'm not thinking it is the problem.
The air ride is staying up so I don't think it is leveling valves.
More ideas???
Thanks
--Mike
Another question...could the inversion valve develop a leak? Enough of one as to not let the system air up? I tried to pressurize the system from both front and rear external ports and I just get the same leak noise from the same place. I have a 3 gal. tank on my small compressor and it will empty in less then a minute.
--Mike
Mike,
Here's my guess, because this happened to us. Short story - check the unloaders on top of your air compressor.
If you cannot hear an air leak, and you don't have air, that tells me your compressor isn't running. If it is, you should hear air leaking. That being said, I wouldn't waste time with your little compressor trying to find/fix a leak. I would investigate your compressor.
I had to take the top cover off of our compressor, and manually work the unloaders. Basically, they were stuck in the "unloaded" position. After I manually worked them, they were stuck in the "loaded" position, and the air dryer would purge every minute or so. Didn't hurt anything, and we had air.
Make sense?
Best of luck!
John
Mike, are you saying that your portable compressor is not able to charge the complete bus air system and all of it's tanks. ? I would certainly do that and check for leaks
or are you saying that the engine compressor is not able to charge the bus air system.?
Both
Quote from: FolkBus on September 18, 2015, 05:37:38 AM
Both
THEN IT WOULD SEEM TO ME THAT THERE IS A MASSIVE LEAK SOMEWHERE ???
AND NO i am not shouting, i am to lazy to retype this... ;D
You may have cracked a brake hose.
BTW, since when do MC5s have spring brakes? Did you replace the DD3s?
A little more research and yes I do have DD3s. Yes I do have a massive leak and I do believe it is a split/cracked line. I had to work in Denver today. Thank heavens I got way off the highway and the CSP is ok with me being here while I finish my work in town (today and tomorrow) then repairs begin.
Thanks to all for the help so far
--Mike
The air bags and air beam are in the way for normal spring brakes on a MCI 5 but if you can find a set of the Maxi spring brakes they will fit that is what I installed on my 5, back then they were easy to find at Mack Truck or the outfit in Texas that manufactured the Maxi's.
I didn't think he had springs but you never know
Mike I still think it is a diaphragm in one of the rear wheels is blown. Just saying.
Hi Dave,
Posted an answer to some of your posts on the other board. Question if I have a blown diaphragm would that keep the system from airing up even a little?? Because however I try to get any pressure in the system I can't even get the gauge to twitch.
--Mike
It's been awhile since I worked on my DD3s, but if I'm not mistaken (and someone will correct me if I am), the parking brake requires pressure on the lock port
to keep the rollers from contacting the shaft while in normal operation. There's a line from the inversion valve to the lock port on the chamber. I'm not sure what
the pressure is on this line, but probably 85 or above. It's possible if this line were cracked, it might be enough to keep a tired compressor from airing up the coach.
Quote from: FolkBus on September 18, 2015, 07:02:15 PM
Hi Dave,
Posted an answer to some of your posts on the other board. Question if I have a blown diaphragm would that keep the system from airing up even a little?? Because however I try to get any pressure in the system I can't even get the gauge to twitch.
--Mike
No. The diaphragms are only under pressure when you apply the brakes. When you release the brakes, the spring on the shaft pulls the shaft back into the chamber.
FolkBus , one thing might make troubleshooting difficult is the way different systems are interconnected. For example, in our 4106, the gauge will only register pressure that is in the auxiliary side of the system, and a big enough leak in the brake side of the system will prevent anything from showing on the gauge.
One way you can isolate the systems is step on the treadle hard while there is nothing showing on the gauge, then release the treadle. If you can hear the air release from the brakes when you do this, there is pressure in the brake system. If you can't hear the air release, then there is no pressure on the brake side.
If you study your manual's air system, you should be able to understand what I am getting at.
Good luck running down your problem.
Tom Caffrey
On another board he said there was air leaking out the R-8 valve in the back. His bags are up still which should be on his accessory tank so there should be air in it and the check valve is working on that system. Tells me its in the brake system or e brake system/ parking system, No? Scratching head also.
Hi all,
Found my issue and have a temp fix that is getting me home. I again want to thank everyone on all three of the boards that consoled, educated offered help and lectured me on my follies. The information has been great and has given me a much better idea on the workings and interactions of the MCI air system(s). I am studying the manual for more education.
So as to not keep everyone in to much suspense it was a "massive" leak from a valve just off of the wet tank that feeds the rear leveling valves. The compressor and associated parts are working fine. As was mentioned in my lecture from Brian the air system of a 5 is a case of multiple personalities. Much more education in my future. In the mean time today was beautiful as I cleared 3 11,000ft+ passes with no problem. With a non turbo 8v71 there was lots of time to enjoy the view both going up and downhill. Misters are a wonderful thing.
Again
Thanks to all
--Mike
Quote from: FolkBus on September 20, 2015, 06:54:48 PM
Hi all,
Found my issue and have a temp fix that is getting me home. ...
Great news!! And, for what it's worth, I went to a Bendix Brake School near my bus storage. I learned *a lot* and it gave me info that allowed me to follow the brake system principles on my bus. It was well worth the $300 and the week of classes.
Quote from: Oonrahnjay on September 21, 2015, 06:39:46 AM
Great news!! And, for what it's worth, I went to a Bendix Brake School near my bus storage. I learned *a lot* and it gave me info that allowed me to follow the brake system principles on my bus. It was well worth the $300 and the week of classes.
Lunches are not that great though ;D and they don't cover the DD-3 in great detail they don't even like to talk about 1