Free 7 Day Trial RV GPS App RV Trip Planner Campground Reviews RV Maintenance Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > THE CHASSIS CLUB FORUMS > Freightliner Motorhome Chassis Forum
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 07-17-2021, 11:38 PM   #1
Senior Member
 
Conchasjim's Avatar
 
Join Date: Jun 2012
Location: Albuquerque
Posts: 134
Send a message via AIM to Conchasjim Send a message via Yahoo to Conchasjim
Help needed with air brake issue

I have a 2003 Fleetwood Revolution. I'm having a problem with the air brakes. Whenever I have the brake pedal pressed my air pressures gradually drop. I usually notice while trying to park or maneuver slowly. Or while stopped at a traffic light. It's gone so low as to set off the alarm. I've had my mechanic underneath the rig while the brakes are engaged to listen for any leaks at the cylinders and hears nothing. He wants to start by replacing the governor. Which he says signals the system to pump air. We replaced the main filter with no change. Has anyone experienced this problem? What would you suspect would be the cause?
Conchasjim is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 07-18-2021, 02:11 AM   #2
Senior Member
 
Join Date: Jul 2016
Posts: 900
You have an air leak
__________________
2016 Newmar BSS 3306
Massparanoia is offline   Reply With Quote
Old 07-18-2021, 03:49 AM   #3
Senior Member
 
Freightliner Owners Club
Holiday Rambler Owners Club
Join Date: Jun 2021
Posts: 268
Faulty foot valve or governor would be on my suspect list. The lines to and from the governor should be checked for leaks also. There’s a good troubleshooting checklist here: http://www.suspensionspecialists.com...Trbl_Chart.pdf
__________________
2021 Holiday Rambler Armada 44LE
2021 Jeep Wrangler High Altitude toad w/Ready Brute Elite II
dizcom is offline   Reply With Quote
Old 07-18-2021, 04:06 AM   #4
Senior Member
 
Join Date: Jul 2014
Posts: 27,955
Governors don't cause your problem, changing that won't fix it.

If your air holds while parked ( engine running ) , chock the wheels and push in the parking brake and see if it holds. Do not step on the brake yet !
The pressure should drop some and then hold steady. If not, bad rear brake chamber or park brake lines/control.

If that tests OK, Next, still parking brake off, step on brake pedal and hold. Pressure should drop some, ( or pump back up by now ) and hold .
If it contionues to drop, its got a leak somewhere. Find a new mechanic.
twinboat is online now   Reply With Quote
Old 07-18-2021, 08:34 AM   #5
Senior Member
 
Conchasjim's Avatar
 
Join Date: Jun 2012
Location: Albuquerque
Posts: 134
Send a message via AIM to Conchasjim Send a message via Yahoo to Conchasjim
Air brake problem

Yes, it's obvious there is a leak when the brakes are pressed.
Conflicting responses on the governor could be the cause. Yes / no?
The system does hold pressures with parking brake on. But, isn't that a spring brake system?
Being that both tanks will empty when the brakes are applied, it has to be something common to both, correct?
The foot brake valve sounds like a probable cause. Where is that located? If it's under the dash by the brake pedal, wouldn't I be hearing an air leak?
Thanks for all your responses!
Conchasjim is offline   Reply With Quote
Old 07-18-2021, 08:40 AM   #6
Senior Member
 
Join Date: Oct 2014
Posts: 2,917
Governor is on the SUPPLY side. It can not be the cause of rapid pressure loss only when the brakes are applied.


Since this pressure loss only occurs with service brake application, the issue has to be in either the brake treadle, lines to the brake cans or a leak in a brake can.



Also, not an issue with parking brake part of the system, as it is spring applied, air released. Said another way, the parking brake "release" can is always supplied with air any time the parking brake is off.



Run engine until cut-out pressure is reached. Turn off engine. Press brakes while someone listens for a leak. As twinboat said, once the initial pressure drop, pressure with brake applied should hold steady or go down at most very slowly.
__________________
Brett Wolfe
Ex: 2003 Alpine 38FDDS. Ex: 1997 Safari Sahara. Ex: 1993 Foretravel U240
wolfe10 is online now   Reply With Quote
Old 07-18-2021, 10:06 AM   #7
Senior Member
 
Join Date: Jul 2014
Posts: 27,955
Quote:
Originally Posted by Conchasjim View Post
Yes, it's obvious there is a leak when the brakes are pressed.

Conflicting responses on the governor could be the cause. Yes / no?

The system does hold pressures with parking brake on. But, isn't that a spring brake system?

Being that both tanks will empty when the brakes are applied, it has to be something common to both, correct?

The foot brake valve sounds like a probable cause. Where is that located? If it's under the dash by the brake pedal, wouldn't I be hearing an air leak?

Thanks for all your responses!
I asked if it the air held air with the parking brake OFF. Button in, air holding springs back.

Governor is not involved with brake application.
twinboat is online now   Reply With Quote
Old 07-18-2021, 11:51 PM   #8
Senior Member
 
Conchasjim's Avatar
 
Join Date: Jun 2012
Location: Albuquerque
Posts: 134
Send a message via AIM to Conchasjim Send a message via Yahoo to Conchasjim
Brakes

Ok, pressure holds with parking brake on. We then let the air build until cutoff. Turned engine off and applied service brakes. Pressure drops fairly quickly on both gauges. Mechanic was underneath at each wheel and couldn't hear any leaks. My reasoning says, it has to be something common to both front and rear systems.
Conchasjim is offline   Reply With Quote
Old 07-19-2021, 01:02 AM   #9
Senior Member
 
Join Date: Jun 2016
Posts: 238
you have a pancake leaking on service side will need to have a shop replace it, rubber only is cheap but complete canister is more expensive, might be an air line also on the brake service side, will need to have someone under when brakes are applied. be sure to chock first
__________________
Bill And Jeanne Anglin, Wasilla, Alaska.
1999 Dutch Star 3884, Freightliner, Cat 300, Jeep Liberty Toad.
nutcker is offline   Reply With Quote
Old 07-19-2021, 06:27 AM   #10
Senior Member
 
Fiesta48's Avatar
 
Fleetwood Owners Club
Freightliner Owners Club
Join Date: Nov 2010
Location: Texas
Posts: 3,556
Call Freightliner shops ask for a air brake certified mechanic. This is nothing a common mechanic should be messing with. This is potentially dangerous.
__________________
Full Timers.
2015 Fleetwood Discovery 40E on a Freightliner XCS chassis with a Cummins ISL9 pulling 1 and/or 2 motorcycles, '07 Honda Accord OR a 17' Runabout Boat.
Fiesta48 is offline   Reply With Quote
Old 07-19-2021, 09:35 AM   #11
Senior Member
 
Conchasjim's Avatar
 
Join Date: Jun 2012
Location: Albuquerque
Posts: 134
Send a message via AIM to Conchasjim Send a message via Yahoo to Conchasjim
Nutcracker, What do you mean by "pancake"?
Conchasjim is offline   Reply With Quote
Old 07-21-2021, 01:14 AM   #12
Senior Member
 
Join Date: Jun 2016
Posts: 238
Quote:
Originally Posted by Conchasjim View Post
Nutcracker, What do you mean by "pancake"?
I grew up calling them pancakes, the correct name is air brake chamber, they come in different sizes and a double version for the rear parking brake. I would only replace or work on one of these if you are experienced . They can be very dangerous or fatal if you make a mistake. This link will show what they look like. The Pancake is actually the rubber part inside the canister as the 2nd link shows.

https://www.anythingtruck.com/catego...-chambers.html

https://www.traction.com/en/p/air-br...truck-anldp24l
__________________
Bill And Jeanne Anglin, Wasilla, Alaska.
1999 Dutch Star 3884, Freightliner, Cat 300, Jeep Liberty Toad.
nutcker is offline   Reply With Quote
Old 07-21-2021, 02:39 AM   #13
Junior Member
 
Join Date: Jul 2021
Posts: 5
There is a possibility I have not seen discussed and is starting to really make sense to me. If no air leaks can be heard and air pressure drops rapidly in operation as described the brakes could be way out of adjustment. The OP is describing a loss of pressure during slow maneuvering of the coach, and at stoplights. All of these conditions are low engine speed operation, meaning that air replenishment is at it's minimum. Also common to all of the conditions is a large amount of on-off input to the brake system. I know, wait a minute at a stop light the brakes are just on. This is true, but you are at an idle, and unless you are someone who drives air brakes a lot you will yo-yo the pedal because of the difference in pedal feel from a hydraulic system. On top of this there is creeping- the little start stop as cars move forward closing the gaps.



When the brakes are grossly out of adjustment each application consumes the limited amount of air a lot faster because the brake rod has to travel a lot further to apply the brakes to the drum/rotor.



On a coach the age of the OP's the probability the self adjusters in the brake ratchets have failed is very high, allowing the brakes to become grossly out of adjustment.
RealNiceTent is offline   Reply With Quote
Old 07-21-2021, 06:05 AM   #14
Senior Member
 
Join Date: Jul 2014
Posts: 27,955
Quote:
Originally Posted by Conchasjim View Post
Nutcracker, What do you mean by "pancake"?
The name pancake comes from the rubber diaphragm, or diaphragms, that are inside the brake chamber.
While both, on the dual chamber, were serviceable back in the day, now only the service diaphragm is. To many lost teeth servicing the spring chamber.

If your service brake diaphragm is leaking it can be replaced.
twinboat is online now   Reply With Quote
Reply

Tags
air, brake



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Issue with Brake Pedal return to position and Park Brake issue 8SEC6SPD Workhorse and Chevrolet Chassis Motorhome Forum 4 04-17-2018 03:35 AM
Fuzion 310 Electrical issue. HELP NEEDED PLEASE pilot227 5th Wheel Discussion 9 08-01-2016 08:47 AM
Help Needed Please - National RV water manifold needed or need to rebuild/redesign rmill27 MH-General Discussions & Problems 8 07-23-2015 05:27 AM
Power Gear brand slide out issue, help needed tacking RV Systems & Appliances 13 06-24-2015 11:44 AM
2001 Class C - Engine Issue Help Needed bulldogs101 Class C Motorhome Discussions 8 03-12-2015 11:03 AM


All times are GMT -6. The time now is 03:05 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.