Reply
 
Thread Tools Display Modes
 
Old 05-27-2011, 08:20 AM   #1
Bus Nut
 
bapos's Avatar
 
Join Date: Apr 2011
Location: Cleburne TX
Posts: 606
Air pressure tank leak down

This is my first experience with air breaks so just want to make sure its common amoung other buses? I have a 1983 GMC 336 Ward. I dont expect it to stay pressurized with the amount of years on it. I know lines age.... orings get brittle and seep but is it common to have zero air pressure after a day or so sitting?


When I start it up and let it idle it comes up to pressure and operates properly and continues when it runs. It also maintains pressure for a reasonable time when shut off.

Its not a huge issue I am just curious what are the typical culprits when it comes to these kinds of leaks?


Thanks

Bapos
__________________
Here is my school bus conversion thread http://www.skoolie.net/forum/viewtopic.php?f=9&t=10282

Pics of my conversion @ photobucket http://s18.photobucket.com/albums/b1.../School%20Bus/
bapos is offline   Reply With Quote
Old 05-27-2011, 12:48 PM   #2
Bus Crazy
 
opus's Avatar
 
Join Date: May 2010
Location: Montana
Posts: 1,615
Year: 1995
Coachwork: Blue Bird
Chassis: All-American R/E
Engine: 8.3 Cummins
Rated Cap: 72
Re: Air pressure tank leak down

Yeah, no biggie there. Dont worry about it unless you are bored and want to find the leak.
opus is offline   Reply With Quote
Old 05-27-2011, 04:14 PM   #3
Bus Nut
 
frank-id's Avatar
 
Join Date: Nov 2003
Location: Twin Falls, Idaho
Posts: 808
tank leak down Find the leak

Opus, my fellow bus guy, I very much disagree with your statement about the seriousness of any air leak.... There could be some liability in your advise.
Before a large air leak there is a small leak. A fitting or airline could be beginning a failure. Recently, I drove a bus for a test ride with a bad exhaust. The bus had not been moved for a short time. After a 15 mile test ride, all brakes were lost as the exhaust melted the nylon brake line. This is difficult where there is lots of traffic...... Frank
frank-id is offline   Reply With Quote
Old 05-27-2011, 04:27 PM   #4
Bus Crazy
 
opus's Avatar
 
Join Date: May 2010
Location: Montana
Posts: 1,615
Year: 1995
Coachwork: Blue Bird
Chassis: All-American R/E
Engine: 8.3 Cummins
Rated Cap: 72
Re: Air pressure tank leak down

Liability....dont think so. I challenge you to hop in 100 air brake vehicles currently inspected and in service today. Tell me how many of them have air after 3 days....or even 1 day.

I would assume he would investigate to find the leak and repair it, thats just common sense.
opus is offline   Reply With Quote
Old 05-27-2011, 11:37 PM   #5
Bus Crazy
 
Join Date: Jan 2008
Location: Upstate NY (Mohawk Valley)
Posts: 1,096
Re: Air pressure tank leak down

X2 - What she said.

I was once doing the whole CDL brake check routine on a brand-new Freightliner, while being ribbed by my partner who was also a volunteer fireman. He was kidding me that if I did all the checks like that on a pumper, it would never get off the floor to a fire. I told him if I were a firefighter, I would do it for the weekly truck check, not an alarm.

When I got to the part about building up pressure and then shutting down with my foot on the treadle and listening for leaks, sure enough there was a slight hiss up front. The master valve got replaced by Freightliner under warranty, and I never got kidded again.

EDIT: There are a whole lot of perfectly usable vehicles with air brakes that do not keep up pressure when parked long-term. But I would want to know WHERE it was losing air, if only for my piece of mind. I also would want to do the refill time test to know that the compressor could fill the tanks faster than they leaked.
__________________
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.
Redbear is offline   Reply With Quote
Old 05-28-2011, 02:42 AM   #6
Site Team
 
freakn's Avatar
 
Join Date: Dec 2010
Location: Southeast British Columbia
Posts: 106
Year: 2003
Coachwork: Bluebird
Chassis: International
Engine: DT466E
Rated Cap: 72
Re: Air pressure tank leak down

Air systems should hold for 3-4 days. At our firehall, our 1998 IH engine will hold 100 psi for over 3 weeks. Our 2 month old Freightliner will go to 0 psi in 36 hours. Go figure, my bus now will drop down to 60 psi after 2 days. Any air leak should be checked out. Small leaks turn big, fast.
__________________
Living the dream in the Kootenays
freakn is offline   Reply With Quote
Old 05-28-2011, 04:03 PM   #7
Bus Nut
 
bapos's Avatar
 
Join Date: Apr 2011
Location: Cleburne TX
Posts: 606
Re: Air pressure tank leak down

I appreciate the input but I havent heard much on usual suspects of this? I plan on chasing lines with soap and water to see where some leaks may be coming from. I know this bus holds air for a day with no issues so Im not overtly worried about it but as noted.... small leaks turn in to big ones.

I am use to dealing with leaky vaccuum lines as I have a 1968 Caddy that has vaccuum door locks so I will buff off the rust of that witch hunt and and find leaks....

I think its a reasonable subject that people probably dont think about.

Again thanks for the input.
__________________
Here is my school bus conversion thread http://www.skoolie.net/forum/viewtopic.php?f=9&t=10282

Pics of my conversion @ photobucket http://s18.photobucket.com/albums/b1.../School%20Bus/
bapos is offline   Reply With Quote
Old 05-28-2011, 06:22 PM   #8
Bus Geek
 
lapeer20m's Avatar
 
Join Date: Nov 2003
Location: near flint michigan
Posts: 2,653
Re: Air pressure tank leak down

in michigan, it is acceptable to loose 3 psi in 5 minutes when engine is off and parking brake is set.

http://www.michigan.gov/documents/bu...on_81255_7.pdf
__________________
Quis custodiet ipsos custodes (who will watch the watchmen?)
lapeer20m is offline   Reply With Quote
Old 05-30-2011, 04:46 AM   #9
Mini-Skoolie
 
Jive Turkey's Avatar
 
Join Date: Jun 2009
Location: Alberta
Posts: 47
Re: Air pressure tank leak down

Air Brake system testing.
Attached Images
File Type: jpg air brake 001.jpg (245.2 KB, 482 views)
File Type: jpg air brake 1 001crop.jpg (371.1 KB, 482 views)
File Type: jpg air brake 2 001 crop.jpg (106.0 KB, 482 views)
Jive Turkey is offline   Reply With Quote
Old 05-30-2011, 05:26 AM   #10
Mini-Skoolie
 
Jive Turkey's Avatar
 
Join Date: Jun 2009
Location: Alberta
Posts: 47
Re: Air pressure tank leak down

The amount of air leakage while the vehicle is parked while not running isn't of any real concern. The things you need to be concerned with are the time build up of air pressure, governor cut in and cut out pressures, supply circuit leakage and delivery circuit leakage. I used to drive trucks back in the early to mid nineties and some of them would dump all their air in just a couple of hours (2-3) and the air brake system worked just fine even in heavy use. If you really want to be a stickler you can go round with soapy water and spray everything down until you find leaks but it isn't necessary.
Jive Turkey is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tire Pressure? TygerCub Conversion General Discussions 20 07-19-2012 08:11 PM
pressure tank cheezypsnookle Conversion General Discussions 6 04-17-2010 10:52 PM
Air pressure to the gas pedal WHISPERS Conversion General Discussions 7 11-12-2008 10:52 PM
Correct Oil Pressure cooter Everything Else | General Skoolie Discussions 6 01-09-2007 02:10 PM
Tire Pressure gealto Everything Else | General Skoolie Discussions 4 09-12-2004 05:42 PM

» Virginia Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 01:12 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.