|
05-11-2021, 08:23 AM
|
#1
|
Bus Nut
Join Date: Jul 2019
Location: Freedom Field, New Mexico
Posts: 459
Year: 1998
Coachwork: International
Chassis: Amtrans
Engine: 444E
Rated Cap: 84 pas
|
Occasional slow air buildup.
This usually happens when it is below freezing, but has happened when it is much warmer. Occasionally, not often, it will take a long long time for air pressure to build up on my 98 international with the t444e. It will build up to 60 or 70psi and then just stall there. Once it does build up it is no problem and may not happen for weeks. This is a daily driver. Any guidance will be appreciated.
|
|
|
05-11-2021, 11:47 AM
|
#2
|
Bus Nut
Join Date: Aug 2019
Location: Auburn, WA
Posts: 785
Year: 2000
Coachwork: IC / Amtran
Chassis: 3000 / 33' Flat Nose
Engine: IC T444E / Allison MT643
Rated Cap: 72 Kids / 48 Adults
|
I hate intermittent issues. Frustrating.
I don't have any real answer, but here's what my understanding is of how the system works.
IF you have three tanks, Primary (back wheels), Secondary (front) and Auxiliary (accessories and emergency), in general, the auxiliary will not fill up until the primary and secondary have reached whatever the pressure amount is for your buses sensor. I believe this is usually 60lbs.
If for some reason the sensor or fixture that keeps the auxiliary from filling until the other tanks reach 60lbs, maybe that's when it takes longer?
Have you done the soapy water spray test on your air lines and connections?
Just a thought. Hope you resolve it soon.
__________________
Steve
|
|
|
05-11-2021, 07:35 PM
|
#3
|
Bus Nut
Join Date: Jul 2019
Location: Freedom Field, New Mexico
Posts: 459
Year: 1998
Coachwork: International
Chassis: Amtrans
Engine: 444E
Rated Cap: 84 pas
|
Quote:
Originally Posted by Simplicity
I hate intermittent issues. Frustrating.
I don't have any real answer, but here's what my understanding is of how the system works.
IF you have three tanks, Primary (back wheels), Secondary (front) and Auxiliary (accessories and emergency), in general, the auxiliary will not fill up until the primary and secondary have reached whatever the pressure amount is for your buses sensor. I believe this is usually 60lbs.
If for some reason the sensor or fixture that keeps the auxiliary from filling until the other tanks reach 60lbs, maybe that's when it takes longer?
Have you done the soapy water spray test on your air lines and connections?
Just a thought. Hope you resolve it soon.
|
Thanks for the input. Yup a few times when it didn't want to build up even at 1000 rpm, I crawled under with the spray bottle. No bingo.
One thing to note: when it is slow both pressure gauges will just get between 20 and 60 then sit.
|
|
|
05-12-2021, 11:25 AM
|
#4
|
Bus Nut
Join Date: Aug 2019
Location: Auburn, WA
Posts: 785
Year: 2000
Coachwork: IC / Amtran
Chassis: 3000 / 33' Flat Nose
Engine: IC T444E / Allison MT643
Rated Cap: 72 Kids / 48 Adults
|
Maybe you can find something in here?
Advanced Troubleshooting Guide for Air Brake Compressors*
https://www.bendix.com/media/documen...otingguide.pdf
__________________
Steve
|
|
|
05-12-2021, 11:50 AM
|
#5
|
Bus Crazy
Join Date: Oct 2017
Posts: 1,222
Year: 1999
Coachwork: BlueBird
Chassis: TC1000 HandyBus
Engine: 5.9L 24V-L6 Cummins ISB
Rated Cap: 26 foot
|
I'm just learning about air brake systems, so take my comments as just that......
I was waiting to see if anyone else would chime in with more experience, but since not......
I'm guessing the governor needs rebuilding.
I would remove the tube coming off the compressor, and check for oil there. If there is a lot of oil, I'd replace the compressor also. Mine came with the kit to rebuild the governor.
My rebuilt compressor also said to check the said tube for oil that has converted to carbon, which could block the tube and lead to lower pressure or long pressure-build-up times.
If you could, then with the tube still disconnected at the compressor, try to add in a pressure gauge (temporarily) to see if the compressor is actually producing enough pressure. If it is, then it is not the governor. However, it may actually be cheaper and easier to just rebuild the governor than to get the supplies and install them for the temporary gauge.
Dont forget to replace the desiccant filter also.
__________________
Look at the Sky; look at the River. Isn't it Good?
|
|
|
05-15-2021, 11:15 PM
|
#6
|
Bus Nut
Join Date: Jul 2019
Location: Freedom Field, New Mexico
Posts: 459
Year: 1998
Coachwork: International
Chassis: Amtrans
Engine: 444E
Rated Cap: 84 pas
|
Quote:
Originally Posted by Mountain Gnome
I'm just learning about air brake systems, so take my comments as just that......
I was waiting to see if anyone else would chime in with more experience, but since not......
I'm guessing the governor needs rebuilding.
I would remove the tube coming off the compressor, and check for oil there. If there is a lot of oil, I'd replace the compressor also. Mine came with the kit to rebuild the governor.
My rebuilt compressor also said to check the said tube for oil that has converted to carbon, which could block the tube and lead to lower pressure or long pressure-build-up times.
If you could, then with the tube still disconnected at the compressor, try to add in a pressure gauge (temporarily) to see if the compressor is actually producing enough pressure. If it is, then it is not the governor. However, it may actually be cheaper and easier to just rebuild the governor than to get the supplies and install them for the temporary gauge.
Dont forget to replace the desiccant filter also.
|
Sounds like you are learning the good stuff right quick. Thanks for the "comments" I think I will find them useful.
|
|
|
05-15-2021, 11:17 PM
|
#7
|
Bus Nut
Join Date: Jul 2019
Location: Freedom Field, New Mexico
Posts: 459
Year: 1998
Coachwork: International
Chassis: Amtrans
Engine: 444E
Rated Cap: 84 pas
|
Quote:
Originally Posted by Simplicity
|
Thank you Steve. This looks like a great resource. I am going to print it out and put it in a binder.
|
|
|
05-15-2021, 11:57 PM
|
#8
|
Bus Crazy
Join Date: Oct 2017
Posts: 1,222
Year: 1999
Coachwork: BlueBird
Chassis: TC1000 HandyBus
Engine: 5.9L 24V-L6 Cummins ISB
Rated Cap: 26 foot
|
After my last post, I was thinking more about the "freezing" part of your description.
My system bleeds down to empty overnight in freezing weather, but not when warm. Metal and seals that shrink when they get cold. Could you have a seriously profound version of that happening? That could affect the seal in the governor. When you checked for leaks, was it freezing at the moment? Hard to do with a spray-bottle of soapy water!
The other thing I'm thinking, is that you may have water in your system. It may be freezing and expanding and then holding a valve open? Or maybe water got into the governor. Again, freezing, and expanding, .....
Have you replaced the desiccant filter?
__________________
Look at the Sky; look at the River. Isn't it Good?
|
|
|
05-16-2021, 12:16 AM
|
#9
|
Bus Nut
Join Date: Jul 2019
Location: Freedom Field, New Mexico
Posts: 459
Year: 1998
Coachwork: International
Chassis: Amtrans
Engine: 444E
Rated Cap: 84 pas
|
Quote:
Originally Posted by Mountain Gnome
After my last post, I was thinking more about the "freezing" part of your description.
My system bleeds down to empty overnight in freezing weather, but not when warm. Metal and seals that shrink when they get cold. Could you have a seriously profound version of that happening? That could affect the seal in the governor. When you checked for leaks, was it freezing at the moment? Hard to do with a spray-bottle of soapy water!
The other thing I'm thinking, is that you may have water in your system. It may be freezing and expanding and then holding a valve open? Or maybe water got into the governor. Again, freezing, and expanding, .....
Have you replaced the desiccant filter?
|
I doubt if it is water in the system. It does have a drier that blows of often and we drain the tanks often as well with very little evidence of condensation.
Doesn't have to be freezing cold for this to happen. Below 40 will sometimes mean a long wait for the air to build up.
Where do I find the desiccant filter?
I am thinking the governor may be the culprit, because the last time it happened I went out and tapped on it and the air started building up.
|
|
|
05-16-2021, 10:37 AM
|
#10
|
Bus Crazy
Join Date: Oct 2017
Posts: 1,222
Year: 1999
Coachwork: BlueBird
Chassis: TC1000 HandyBus
Engine: 5.9L 24V-L6 Cummins ISB
Rated Cap: 26 foot
|
The filter is in the "wet" tank. Follow the output line from the compressor, and it first goes to the wet tank.
Tapping on the governor....sounds to me like the problem. Unless there is something else in the system that I don't know about.
__________________
Look at the Sky; look at the River. Isn't it Good?
|
|
|
05-17-2021, 07:01 PM
|
#11
|
Bus Nut
Join Date: Aug 2019
Location: Auburn, WA
Posts: 785
Year: 2000
Coachwork: IC / Amtran
Chassis: 3000 / 33' Flat Nose
Engine: IC T444E / Allison MT643
Rated Cap: 72 Kids / 48 Adults
|
Quote:
Originally Posted by Rock-N-Ruth
I am thinking the governor may be the culprit, because the last time it happened I went out and tapped on it and the air started building up.
|
I love that "tapping" on something mechanical still resolves issues, at least temporarily.
If it is the governor, when you go out to fix it, make sure you address it properly in your best cockney accent "Good morn'n Guvner!"
__________________
Steve
|
|
|
05-17-2021, 08:46 PM
|
#12
|
Bus Geek
Join Date: May 2014
Location: West Ohio
Posts: 3,708
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
|
Governors are cheap. If whacking on yours gets it to function, replace it. They can get gummy from time to time, especially if they're low in the system.
We don't seem to have much trouble with them when they're mounted on the compressor, but the ones that are mounted low near the tanks seem to have issues with trapping moisture, even with a drier in the system.
|
|
|
05-18-2021, 10:42 AM
|
#13
|
Skoolie
Join Date: Oct 2018
Location: Georgia
Posts: 169
Year: 2002
Coachwork: Bluebird
Chassis: Tc2000
Engine: 5.9 24v
Rated Cap: 27
|
Do you have air bag suspension? My bus will air up real quick if the bags didn't deflate, but "stall" just like you described at 60-90 PSI if the bags deflated from being parked non level or for a long time.
|
|
|
06-08-2021, 01:11 PM
|
#14
|
Bus Nut
Join Date: Jul 2019
Location: Freedom Field, New Mexico
Posts: 459
Year: 1998
Coachwork: International
Chassis: Amtrans
Engine: 444E
Rated Cap: 84 pas
|
Quote:
Originally Posted by Simplicity
|
Very helpful. Thank you. A minor adjustment of the air governor did the trick. I also dumped the air tanks, somthing I should have been doing g on a scheduled basis. Got a little oil but less than a teaspoon. Not bad considering I never did it before,(laziness is not my friend.) I've had the bus going on 2 years and 15k miles.
Again thank you for the very helpful troubleshooting guide.
|
|
|
06-08-2021, 01:15 PM
|
#15
|
Bus Nut
Join Date: Jul 2019
Location: Freedom Field, New Mexico
Posts: 459
Year: 1998
Coachwork: International
Chassis: Amtrans
Engine: 444E
Rated Cap: 84 pas
|
Quote:
Originally Posted by Jsneeb
Do you have air bag suspension? My bus will air up real quick if the bags didn't deflate, but "stall" just like you described at 60-90 PSI if the bags deflated from being parked non level or for a long time.
|
This is also the case with my rig. An adjustment to the governor bumped my static pressure up to 130psi. Now the bags dont leak down flat. They hold 40 to 60 psi for days. The system recovers fast at 550 rpm to about 100 psi. If I bump the rpm to 1000 it will build to 130 psi quickly.
|
|
|
|
Thread Tools |
|
Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
» Recent Threads |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|