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Topic: Air Brake Pressure Loss During Hi Boost On a Long Grade (Read 1461 times) previous topic - next topic

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #25 –
Quote from: zmpm01 –
Compressor discharge hose length should be 12 feet to cool the air going to the dryer to help it be efficient. I wanted to cut it down real bad. thought that was stupid why's the hose so dam long..

Another thing learned.  I was under the coach a week or so ago replacing my D2. I was looking at the line going from compressor to dryer and it went back and forth.  I had not put much thought into why, just noticed that it was way longer then needed.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #26 –
Quote from: turbojack –
Another thing learned.  I was under the coach a week or so ago replacing my D2. I was looking at the line going from compressor to dryer and it went back and forth.  I had not put much thought into why, just noticed that it was way longer then needed.
You can cut it down but the result will be that you will melt the inside of the air dryer.  I had to replace my hose and wondered why it was so long,  when I checked I was told it was that long to allow the air to cool Just enough to avoid the melt-down
Chris
1999 U 320 DGFE
Build Number 5523
Chris & Elka Lang
In the field, Lonoke AR

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #27 –
That makes sense. Maybe my old unit had issues.

I've had my dryer apart and can't think of anything that would melt inside. There are2 or 3  brass check  valves ,the cartridge chamber , blowoff valve .  The only plastic might be inside of the purge valve.
 My pressure line is not 12 ft. Maybe 6 as it is direct from compressor to dryer .

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #28 –
There is plastic in mine and it might be called the purge valve.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #29 –
Quote from: Protech Racing –
That makes sense. Maybe my old unit had issues.

I've had my dryer apart and can't think of anything that would melt inside.

Turbo saver valve has some parts attached that would be subject to heat stress.

The turbo protection valve, located at the dryer inlet, prevents turbo pressure loss when unloading.

I believe the turbo saver valve only gets activated over 20 PSI boost.
Doug W.
96 36' U270 CSGI #4946
04 Toyota Tacoma 4x4
PNW

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #30 –
Maybe this part is connected to the OP. Issue?

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #31 –
Thanks Doug that's the name of the valve I meant is plastic.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #32 –
That could be part of his issue at boost.

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #33 –
Update to the air pressure loss during hi boost, Thanks everyone for the suggestions as where to look and idea's. I pulled the air dryer out and Installed a rebuild kit, The turbo saver valve and pop off valve looked brand new. The discharge check valve was stuck open and full of crap.(Yes the other air tank check valves are holding)     
Also the foot-well cover air actuator and the air regulator where both leaking. (Thanks Craneman for that suggestion as a possible leak source) I also did a extreme leak check and brake system check. And performed the checks some have recommended.

I also had MOT perform a leak check just to put another set of eye's on it. They found 2 small leak's I missed. I also had a mechanic drive the coach he stated it's acting normal to him the way the air compressor loads and unloads and maintaining pressure on the grades...

It's hard to find a really long grade pull in East Texas It doesn't lose pressure now on the grades I can find, but it really doesn't gain pressure either.

One question I have do the coaches have active air ride? should the leveling valves be active or any part of the air ride system be bleeding air while driving down the road in travel mode? The reason I ask is when my coach is sitting parked with the engine running the air pressure is rock solid stable, but driving down the road I do lose pressure, I've always chocked it up to the air ride system being active??

I plan to leave out in a few days for Montana and the Pacific Northwest, I guess I'll get to check if things are back to normal or not, I feel I've done all I can do and now I just need to put it to the test... The worst I'll have to do is slow down and back off the throttle on the long steep grades.

Thanks for the help, ideas and phone calls. Mike






Mike & Donna Mariana + Angel & Rusty
2003 U295 3620
Build# 6118
2021 Jeep Wrangler 392

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #34 –
Quote from: zmpm01 –
One question I have do the coaches have active air ride? should the leveling valves be active or any part of the air ride system be bleeding air while driving down the road in travel mode?
I'm not sure what you mean by "active air ride".  If you mean do the individual air bags and/or shocks at each corner constantly make fine adjustments to the ride height or suspension response, then No they do not.

However, the three height control valves can be active - especially the two at the rear end - depending on the road conditions.  When you are on a curvy road with lots of small undulations (whoop-de-doos) the height control valves may be exhausting air at various times trying to maintain the proper suspension height front to rear and side to side.

You will also deplete the air system pressure more rapidly when driving in conditions that require frequent use of the air brakes.  If you use your retarder then this will be much less of a factor.

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #35 –
I'm with Chuck. You will use more air from your tanks when driving rough/ uneven roads verses smooth roads, therefore the constant need to fill the tanks back up.
Richard & Betty Bark & Keiko our Golden Doodle
2003 U320T 3820 PBDS
Build # 6215
MC # 16926
2016 Chevrolet Colorado 4X4 diesel

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #36 –
Thanks for the explanation.
Mike & Donna Mariana + Angel & Rusty
2003 U295 3620
Build# 6118
2021 Jeep Wrangler 392
 

Re: Air Brake Pressure Loss During Hi Boost On a Long Grade

Reply #37 –
Many of the Cummons engines have the variable turbo chargers. The later ones are pneumatically operated with the air supply coming from the rear brake-suspension supply. The Pneumatic actuator or controls for it could be failing. I would look there. Another symptom is delayed boost response or pressure.

Dennis
Bohemia NY
2008 Nimbus 342
Dennis Haynes
Bohemia NY
2008 Nimbus 342 SE Carlyle
Build #6475
Motorcade #19148