Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
 
Old 10-26-2020, 01:32 PM   #1
Bus Nut
 
Join Date: May 2017
Location: Houston TX
Posts: 570
Year: 1998
Coachwork: Amtran
Chassis: International
Engine: dt466e
I think I have a air brake pressure leak

I went to start my bus today after months of it sitting and when I want to put my foot on the brake and release the brakes the brake pressure light came on and started buzzing. I figured I'd let it run for a bit to let the air pressure build back up but I found that it wasn't going up at all. After a while I went to take a look under the bus to see if I can spot anything obvious and I noticed a mild smell that I never smelled before. Also, I wasn't for certain but it sounded ike it was making a noise that wasn't there before too.

I climbed under to try to get as close to the sound as I can and I moved my hand around and found that there was some air shooting out from somewhere. It wasn't a big amount of air and I'm not sure if that's just something that's always been but I recorded video of where the air is coming from to see if anybody will be able to tell me if this is a air leak issue. Also, I took more video of the same area of something that looks like it was bubbling

Any help would be appreciated. I have to move my bus from where it's stored at before tomorrow or I get charged the monthly rate. Hopefully this is easy to fix on my own it's a 98 International 3800 dt466e Amtran

Here's a link to the video

https://streamable.com/fmvxux


Thanks

adic27 is offline   Reply With Quote
Old 10-26-2020, 05:04 PM   #2
Bus Geek
 
Join Date: May 2014
Location: West Ohio
Posts: 3,660
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
That's the air dryer. Where it's leaking at is the exhaust of the air dryer. If yours is leaking out of the exhaust all the time like that, you need to either rebuild or replace it the air dryer assembly.

That exhaust has a valve above it that is supposed to seal up and allow the compressor to push air through the desiccant(drying material) and into the wet tank. If that valve is broken or stuck open, it will continuously push air out of the dryer and never build pressure.

Take a picture of the whole dryer assembly and we'll see if we can figure out which dryer you have and what rebuild kit/reman'd assembly you need.
__________________
My build: The Silver Bullet https://www.skoolie.net/forums/f11/p...llet-9266.html
Booyah45828 is offline   Reply With Quote
Old 10-26-2020, 05:05 PM   #3
Bus Geek
 
Join Date: May 2014
Location: West Ohio
Posts: 3,660
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
It looks like an ad9 dryer, but I'd like to see a clear picture before I send you on a wild goose chase.
__________________
My build: The Silver Bullet https://www.skoolie.net/forums/f11/p...llet-9266.html
Booyah45828 is offline   Reply With Quote
Old 10-26-2020, 06:05 PM   #4
Bus Crazy
 
Join Date: May 2016
Location: Georgia
Posts: 2,264
Year: 2001
Coachwork: Blue Bird
Chassis: IH
Engine: T444E
Rated Cap: 14
Booyah's right. These are somewhat common failure items, usually when the "filter"/cartridge is never replaced. The cartridge should be replaced at least annually on a "daily driver".
Brad_SwiftFur is offline   Reply With Quote
Old 10-26-2020, 07:04 PM   #5
Bus Nut
 
Join Date: May 2017
Location: Houston TX
Posts: 570
Year: 1998
Coachwork: Amtran
Chassis: International
Engine: dt466e
Quote:
Originally Posted by Booyah45828 View Post
It looks like an ad9 dryer, but I'd like to see a clear picture before I send you on a wild goose chase.

Thanks for replying. Someone else also bet on it being an AD-9. I'll take pictures when the sun comes back up. He also said there's different configurations so you gotta be careful when determining the replacement
adic27 is offline   Reply With Quote
Old 10-26-2020, 08:10 PM   #6
Bus Nut
 
Join Date: May 2017
Location: Houston TX
Posts: 570
Year: 1998
Coachwork: Amtran
Chassis: International
Engine: dt466e
Either of you know what the bubbling is all about in the last part of the of the video?
adic27 is offline   Reply With Quote
Old 10-26-2020, 08:21 PM   #7
Bus Geek
 
Join Date: May 2014
Location: West Ohio
Posts: 3,660
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
The bubbling is air bypassing one of the o-rings on the purge valve assembly. pull it apart and see if you need an entire valve or just a rebuild kit. Unclip the heater connector on the bottom, and then remove the 3 bolts and the valve should pop out.

Here is a video that kind of shows it. It isn't mine, and there's minimal audio, but you can get a idea from it.

https://youtu.be/sBwKvY8e-Pg

I seen on amazon they had an ad9 purge valve maintenance kit and new cartridge bundle for 63 bucks. Definitely replace the cartridge because most skoolies neglect to do so.
__________________
My build: The Silver Bullet https://www.skoolie.net/forums/f11/p...llet-9266.html
Booyah45828 is offline   Reply With Quote
Old 10-27-2020, 01:28 PM   #8
Bus Nut
 
Join Date: May 2017
Location: Houston TX
Posts: 570
Year: 1998
Coachwork: Amtran
Chassis: International
Engine: dt466e
Thanks a lot!
adic27 is offline   Reply With Quote
Old 10-27-2020, 01:34 PM   #10
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 18,707
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
sure looks like a Bendix AD-9 or AD-4.. both were used on school busses.. and both pretty common.. judging from the outside of that one the dessicant cartridge hasnt been changed in a long time..



I would replace it with a reman unit..



since bendix recommends swapping any AD-4 for an AD-9 as a replacement, its a good bet to get an AD-9 reman unit..


yours is a Heated air dryer . . be sure to get a heated one as the replacement..
cadillackid is offline   Reply With Quote
Old 10-27-2020, 01:53 PM   #11
Bus Geek
 
Join Date: May 2014
Location: West Ohio
Posts: 3,660
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
It's an ad-9 based off the exhaust housing in the pictures. The ad9 has a 3 bolt whereas the ad4 has a 4 bolt.
__________________
My build: The Silver Bullet https://www.skoolie.net/forums/f11/p...llet-9266.html
Booyah45828 is offline   Reply With Quote
Old 10-27-2020, 07:55 PM   #12
Bus Nut
 
Join Date: May 2017
Location: Houston TX
Posts: 570
Year: 1998
Coachwork: Amtran
Chassis: International
Engine: dt466e
Good news!... I think..

After reading the replies here and another place I asked, something made me twist the bolt where I guess the "cartridge" is (?) And from what I can tell it seemed to have moved up slightly. I decided to start the engine and see if that helped and low and behold, the air pressure gauge started climbing! And quite quickly. At about 60 or 90 psi the light and buzzard went off.

Few questions: Should I twist it more until it stops? Is it supposed to be easy to turn? It wasn't loose loose but not tight as one would think. The bolt itself wasn't turning. Well it was but along with the white disc looking thing right above it.

I wanted to get some feedback at this point before I drove it to where I'm taking it, which is not that far at all.

Thanks for all of your help guys!
adic27 is offline   Reply With Quote
Old 10-27-2020, 08:13 PM   #13
Bus Nut
 
Join Date: May 2017
Location: Houston TX
Posts: 570
Year: 1998
Coachwork: Amtran
Chassis: International
Engine: dt466e
Here's an image to point out what I twisted clockwise

Also, typo in the pics text. *Bolt, not but.
Attached Thumbnails
IMG_20201027_201015.jpg  
adic27 is offline   Reply With Quote
Old 10-27-2020, 08:26 PM   #14
Bus Crazy
 
Join Date: May 2016
Location: Georgia
Posts: 2,264
Year: 2001
Coachwork: Blue Bird
Chassis: IH
Engine: T444E
Rated Cap: 14
In your case I'd feel OK moving it a short distance while the thing is building air pressure, but I'd plan on changing the air dryer before too much longer. Sounds like maybe you dislodged whatever was making it stick open and it's likely to do so again at some point in the not-so-distant future.
Brad_SwiftFur is offline   Reply With Quote
Old 10-27-2020, 11:53 PM   #15
Bus Nut
 
Join Date: May 2017
Location: Houston TX
Posts: 570
Year: 1998
Coachwork: Amtran
Chassis: International
Engine: dt466e
Quote:
Originally Posted by Brad_SwiftFur View Post
In your case I'd feel OK moving it a short distance while the thing is building air pressure, but I'd plan on changing the air dryer before too much longer. Sounds like maybe you dislodged whatever was making it stick open and it's likely to do so again at some point in the not-so-distant future.
Yea, I was anxious and just moved it. When I first tried to drive it it wouldn't move. Forward nor reverse. I tried a decent amount of times and then started researching what could be wrong. I found nothing so I tried again and noticed the bus moved forward "very" little and vice versa backwards but like it was chucked or had a really strong emergency brake applied. Kinda like it was stuck. I tried one more time in reverse and then drive and it kinda mad a tank sound and drove forward as usual. Sounded like it released itself from a chain or something. It wasn't attached to anything BTW. What do you suppose caused this? Hopye it's not a sign of transmission issues to come ��

Anyways, I took another look at the air dryer and it seems kind of wet. Either way, s you suggested, I will replace it since it seems like easy task and the part is cheap. What do you think that wetness indicates? Also, do you think twisting that nut some more will make it go away? Aside from one drop, there was no liquid leaking from it. Kinda like condensation. I took a pic.

Since I've had the bus, after shutting the engine off I've always heard like a long faint hiss. More audible when I stick my head under the bus. I figured it's just how the air brake system works but with this situation I found it's actually the air dryer (I think). Is that normal? It goes away after a short while.

Air pressure seem great BTW

Thanks again guys
Attached Thumbnails
IMG_20201027_234334.jpg  
adic27 is offline   Reply With Quote
Old 10-28-2020, 06:57 AM   #16
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 18,707
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
Quote:
Originally Posted by Booyah45828 View Post
It's an ad-9 based off the exhaust housing in the pictures. The ad9 has a 3 bolt whereas the ad4 has a 4 bolt.



ha! cool stuff I always went by heated or not but I learned that both can be heated.. now I know what to look for when determining AD-4 vs AD-9..
cadillackid is offline   Reply With Quote
Old 10-28-2020, 07:18 AM   #17
Bus Geek
 
Join Date: May 2014
Location: West Ohio
Posts: 3,660
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
If the bus has sat for a while, the shoes/rollers/s-cams might be frozen because of rust. That essentially means the brakes are still applied, so you're not going anywhere. To free them, you can push in the parking brake release, chock the wheels, and then whack the brake drums with a big hammer. You could also try and rock it back and forth like you did and that will sometimes free them too. Don't forget to chock the wheels, your life depends on it. That simple step should be done anytime your working under your bus.

As far as the faint hissing, that further points to the fact that you need to rebuild or replace your air drier. The condensation on the bottom shows that the air drier is working. Everytime the drier purges, or goes whoosh, it's blowing dry air past the wet desiccant purging the moisture out of the desiccant and out the exhaust into the environment.

This whole bus sounds like it needs gone through before you plan on driving it anywhere. Filters need changed, driers need fixed, and hit every grease zerk you can find with grease.
__________________
My build: The Silver Bullet https://www.skoolie.net/forums/f11/p...llet-9266.html
Booyah45828 is offline   Reply With Quote
Old 10-28-2020, 09:45 AM   #18
Skoolie
 
Phantom5824's Avatar
 
Join Date: May 2019
Location: Southern Maine
Posts: 122
Year: 1988
Coachwork: Gillig
Chassis: Phantom 40'
Engine: DDECII 6V92T Allison MT647
Rated Cap: 37,400 lbs of potential
Quote:
Originally Posted by Booyah45828 View Post
If the bus has sat for a while, the shoes/rollers/s-cams might be frozen because of rust. That essentially means the brakes are still applied, so you're not going anywhere. To free them, you can push in the parking brake release, chock the wheels, and then whack the brake drums with a big hammer. You could also try and rock it back and forth like you did and that will sometimes free them too. Don't forget to chock the wheels, your life depends on it. That simple step should be done anytime your working under your bus.

As far as the faint hissing, that further points to the fact that you need to rebuild or replace your air drier. The condensation on the bottom shows that the air drier is working. Everytime the drier purges, or goes whoosh, it's blowing dry air past the wet desiccant purging the moisture out of the desiccant and out the exhaust into the environment.

This whole bus sounds like it needs gone through before you plan on driving it anywhere. Filters need changed, driers need fixed, and hit every grease zerk you can find with grease.



+1 on everything that BooYah said,
and, get into the habit of regularly blowing the condensate out of your air tanks. Most important if your bus is in a freezing climate.
Best
Rich
Phantom5824 is offline   Reply With Quote
Old 10-28-2020, 09:28 PM   #19
Bus Nut
 
Join Date: May 2017
Location: Houston TX
Posts: 570
Year: 1998
Coachwork: Amtran
Chassis: International
Engine: dt466e
Quote:
Originally Posted by Booyah45828 View Post
If the bus has sat for a while, the shoes/rollers/s-cams might be frozen because of rust. That essentially means the brakes are still applied, so you're not going anywhere. To free them, you can push in the parking brake release, chock the wheels, and then whack the brake drums with a big hammer. You could also try and rock it back and forth like you did and that will sometimes free them too. Don't forget to chock the wheels, your life depends on it. That simple step should be done anytime your working under your bus.

As far as the faint hissing, that further points to the fact that you need to rebuild or replace your air drier. The condensation on the bottom shows that the air drier is working. Everytime the drier purges, or goes whoosh, it's blowing dry air past the wet desiccant purging the moisture out of the desiccant and out the exhaust into the environment.

This whole bus sounds like it needs gone through before you plan on driving it anywhere. Filters need changed, driers need fixed, and hit every grease zerk you can find with grease.
Really appreciate all the info and tips. I've been looking to change the oil and filter among other maintenance tasks. Definitely gonna replace the air dryer and keep an eye on it for now. I was thinking to spray, not only the current air dryer, but the whole underside with degreaser letting it sit and then blowing it with an 1 hp air compressor. Sound ok?

Thanks!
adic27 is offline   Reply With Quote
Old 10-28-2020, 09:40 PM   #20
Bus Crazy
 
Join Date: May 2016
Location: Georgia
Posts: 2,264
Year: 2001
Coachwork: Blue Bird
Chassis: IH
Engine: T444E
Rated Cap: 14
Quote:
Originally Posted by adic27 View Post
Yea, I was anxious and just moved it. When I first tried to drive it it wouldn't move. Forward nor reverse. I tried a decent amount of times and then started researching what could be wrong. I found nothing so I tried again and noticed the bus moved forward "very" little and vice versa backwards but like it was chucked or had a really strong emergency brake applied. Kinda like it was stuck. I tried one more time in reverse and then drive and it kinda mad a tank sound and drove forward as usual. Sounded like it released itself from a chain or something. It wasn't attached to anything BTW. What do you suppose caused this? Hopye it's not a sign of transmission issues to come ��

Anyways, I took another look at the air dryer and it seems kind of wet. Either way, s you suggested, I will replace it since it seems like easy task and the part is cheap. What do you think that wetness indicates? Also, do you think twisting that nut some more will make it go away? Aside from one drop, there was no liquid leaking from it. Kinda like condensation. I took a pic.

Since I've had the bus, after shutting the engine off I've always heard like a long faint hiss. More audible when I stick my head under the bus. I figured it's just how the air brake system works but with this situation I found it's actually the air dryer (I think). Is that normal? It goes away after a short while.

Air pressure seem great BTW

Thanks again guys

Yeah, as Booyah said, the brakes can stick after being parked for some time - or applied when the brakes were fairly hot. Sure, you could do as described and whack 'em with a hammer, or do what many drivers do and rock the vehicle forward/back until the brakes let go (my usual method if/when this happens).


The part is called an "Air Dryer" for a reason! It's supposed to take excess moisture out of the compressed air. Naturally there will be water in this part, which it's supposed to purge periodically with a nice reassuring "Pshhh!" (usually right as the air compressor cuts-out).


Quote:
Originally Posted by adic27 View Post
Really appreciate all the info and tips. I've been looking to change the oil and filter among other maintenance tasks. Definitely gonna replace the air dryer and keep an eye on it for now. I was thinking to spray, not only the current air dryer, but the whole underside with degreaser letting it sit and then blowing it with an 1 hp air compressor. Sound ok?

Thanks!

If you spray the underside with degreaser, why not go on and give the underside a nice bath while you're at it?
Brad_SwiftFur 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


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 03:09 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.