You are not logged in or registered. Please login or register to use the full functionality of this board...
Newell Gurus
Dash Air Gauges - Printable Version

+- Newell Gurus (https://newellgurus.com)
+-- Forum: Technical Discussions (https://newellgurus.com/forumdisplay.php?fid=3)
+--- Forum: Air Operated Systems and Leaks (https://newellgurus.com/forumdisplay.php?fid=33)
+--- Thread: Dash Air Gauges (/showthread.php?tid=6193)

Pages: 1 2 3


Dash Air Gauges - Tfrazier - 07-18-2021

Hey all, 
This may or may not be a big deal. Yesterday I went to take my coach out for its weekly drive. When I started her up, I notice that the break air gauge had a different reading than the supply air gauge. This has never happened. They always read the same and climb at the same rate after I start the engine. the break air gauge was showing about 80 psi the supply gauge was at 0.

I went out and walked around the coach. Everything looked normal and for being parked for a week, the body height was about where it always is after this amount of time. I took my tire covers off and went back inside. To my relief both gauges showed the same reading at 110 psi and everything was fine. Took it out for a 30 minute drive. Everything felt fine and drove/handled as expected.

Fast forward to today. Went back to coach to do a follow up on the gauges. Same thing. The break gauge was at 100, the supply gauge showed 0. Again, did my walk around and it was sitting up just fine. I started the coach. It took about 1 minute and the supply gauge caught up to the break gauge.

any ideas? Should I be concerned?

Thanks, Tony


RE: Dash Air Gauges - HoosierDaddy - 07-18-2021

You have a leak at the supply side .There is a check valve that doesn’t allow a leak in the supply side to pull air from the brake side. The compressor will fill both sides.


RE: Dash Air Gauges - Tfrazier - 07-19-2021

Thanks for the help. Will start the process of tracking for the leak(s), right after go back and review some of the videos from the forum on this subject.


RE: Dash Air Gauges - encantotom - 07-19-2021

what dean said is spot on. if both supply and brake go down the same time, then their is a leak and also a bad check valve between the two systems. that check valve is hard to get at on your so good thing it is operating correctly.

now you begin your air leak adventure. on yours, if the airbags are holding steady, then it is a search for the leak.

how fast does it leak down to zero? you should have a 120v air compressor up front somewhere. start using bubbles on the easiest to get at places. the compressor, any regulator/drain bowls, etc.

you have airhorns probably, air vacuum pump, air shifter for the tranny, air step cover perhaps, probably air slide for genny, etc.

just start looking

tom


RE: Dash Air Gauges - Tfrazier - 07-19-2021

Thanks for the advice Tom. I am going to start working on it this weekend but I will take a ride over tomorrow and let you know how fast it is leaking down to zero.
I've read most of the posts and watched the all the videos linked on the site but I'm still intimidated by this air system.


RE: Dash Air Gauges - encantotom - 07-19-2021

baby steps one thing at a time.

stop at a dollar store and get a quart bottle of kids bubbles and a spray bottle.

spray and watch for bubbles

do it in chunks

tom


RE: Dash Air Gauges - HoosierDaddy - 07-19-2021

I would suggest that anybody not familiar with air brake systems check with your local BMV for a CDL handbook that covers air brake systems. My local BMV provided one when I was preparing for the CDL test. Here is a basic excerpt from the BMV website.

"With the air pressure built up to governor cutoff (120 – 140 psi), shut off the engine leaving the key in the “on” or “battery charge” position, chock your wheels if necessary, release the parking brake (all vehicles), and the tractor protection valve (combination vehicle) and fully apply the foot brake. Hold the foot brake for one minute. Check the air gauge to see if the air pressure drops more than three pounds in one minute (single vehicle) or four pounds in one minute (combination vehicle).
Begin fanning off the air pressure by rapidly applying and releasing the foot brake. Low air warning devices (buzzer, light, flag) should activate before air pressure drops below 55 psi or level specified by the manufacturer."

Additionally you could take your coach to a truck shop that does DOT truck inspections. They should thoroughly check the brake system as part of that procedure. The shop I took my Newell to provided me with a checklist of their findings.


RE: Dash Air Gauges - encantotom - 07-19-2021

dean, his air brakes are not leaking. it is only the supply side.

tom


RE: Dash Air Gauges - update - still scratching my head - Tfrazier - 07-24-2021

I spent the day going through the coach looking for air leaks with no succes. 

A little background on my coach. It's a 1992, 38', no tag. Compared to most of the coaches discussed on the forum, my coach is pretty basic.

The only air operated items (besides brakes and suspension) are the generator slide, bay fridge/freezer and the step cover. Oh, and air horns (but they have not worked since I've owned it).  Tom mentioned air vacuum pump and air shifter for the tranny. Don't know about them. I don't have an air toilet, pocket doors, seat, entry door, etc, etc. I only have 3 air tanks (at least that I can find) and all of them are located under the coach. So finding a leak should be pretty straight forward, right? 

Not so fast, I have looked every where I can think to look using the bubbles and the ultra sonic,with no success. I'm sure I missed some, just don't know where. I checked all around the compressor in the front bay and all fittings in the generator bay. I checked both sides of the engine bay and all bays in between. I started under the coach at the front and worked my way to the rear. Along the way, I checked every fitting I could locate and I checked the air tanks, even the brake connections.

I also used the ultrasonic inside the coach. All cabinets, closets, overhead compartments and around the shifter and dash area on the driver 's side.

Where can I find the connection for the airhorns?
Any other ideas/questions from the group?I

Tony


RE: Dash Air Gauges - Tf175 - 07-24-2021

On our '86 the air horn plumbing including solenoid is in the overhead above steering wheel. I  have yet to leak proof the coach , but I was able to minimize the leaks somewhat .
As Richard instructed me , the first thing is to educate yourself on how the systems work . The suspension can be bewildering with all the valving , hoses snaking into unknown areas , etc . And two systems that are involved,  ride height and leveling when parked .
I used a cylinder leak down tester , the type used for diagnosing IC engines . Started at the line from the compressor and then broke it down into sections. 
I think the initial leak was around 25 % , pretty significant. Biggest leak was the Low Air switch on one of the tanks . Smaller leaks at compression fittings on hoses between valving were hard to find.  
I found another tank last year,  hiding above a tank near the propane tank . ( wish I had a pit ! ).
BTW , some frame cross members are in the mix as well , more fittings , drain cocks , etc .
Does one of your tanks have an automatic drain ?

On our '86 the air horn plumbing including solenoid is in the overhead above steering wheel. I  have yet to leak proof the coach , but I was able to minimize the leaks somewhat .
As Richard instructed me , the first thing is to educate yourself on how the systems work . The suspension can be bewildering with all the valving , hoses snaking into unknown areas , etc . And two systems that are involved,  ride height and leveling when parked .
I used a cylinder leak down tester , the type used for diagnosing IC engines . Started at the line from the compressor and then broke it down into sections. 
I think the initial leak was around 25 % , pretty significant. Biggest leak was the Low Air switch on one of the tanks . Smaller leaks at compression fittings on hoses between valving were hard to find.  
I found another tank last year,  hiding above a tank near the propane tank . ( wish I had a pit ! ).
BTW , some frame cross members are in the mix as well , more fittings , drain cocks , etc .
Does one of your tanks have an automatic drain ?