I have had a long standing problem of the front air bags deflating
soon after the bus is parked. The bags will not hold overnight and
sometimes that is all I need before leaving the next day. The jacks
work great but it is just one more thing to do. I have been all over
the bus. I have bubbled and sniffed (ultrasonic leak detector)every
air leak I could find, and I am talking a detail inspection. The two
dry tanks will hold air for 2 weeks but the wet bleeds off way to
soon.
Here is proof that even I get lucky sometimes. I have been working
on the genset quite a bit lately and I just hook up an air line from
the workshop to the schrader on the wet tank and keep it full to
operate the gen air ram. I was in a hurry today to go to lunch with
my wife and tried to whip the air hose of the shrader valve and
snapped it off the air tank fill. All the air in the wet tank
dumped rapidly as I left for lunch. When I got back the front of the
bus is still at ride height. The only thing that makes sense to me
is that I am some how getting pressure to the front dump valve when
there is available air pressure in the wet tank causing the front
bags to deflate.
Anyone got an idea?
Jim
83 FCRB
Yorba Linda, ca
On the 83 Fc35 I owned previously, I had the exact opposite problem.
The rear air bags lost pressure in a couple of hours. In my case, it
was the two rear air leveler valves. I bought new ones from BB,
problem solved.
I may be your single air leveler valve, right in the middle by the
front axle. Since it is under the coach, maybe you can't hear it,
and if your jacks are down, it changes the leveler valve height
setting.
Dan
NM 94 BB BMC 37'
--- In
WanderlodgeForum@yahoogroups.com, "bluebird3208"
wrote:
>
> I have had a long standing problem of the front air bags deflating
> soon after the bus is parked. The bags will not hold overnight and
> sometimes that is all I need before leaving the next day. The
jacks
> work great but it is just one more thing to do. I have been all
over
> the bus. I have bubbled and sniffed (ultrasonic leak detector)every
> air leak I could find, and I am talking a detail inspection. The
two
> dry tanks will hold air for 2 weeks but the wet bleeds off way to
> soon.
>
> Here is proof that even I get lucky sometimes. I have been working
> on the genset quite a bit lately and I just hook up an air line
from
> the workshop to the schrader on the wet tank and keep it full to
> operate the gen air ram. I was in a hurry today to go to lunch
with
> my wife and tried to whip the air hose of the shrader valve and
> snapped it off the air tank fill. All the air in the wet tank
> dumped rapidly as I left for lunch. When I got back the front of
the
> bus is still at ride height. The only thing that makes sense to me
> is that I am some how getting pressure to the front dump valve when
> there is available air pressure in the wet tank causing the front
> bags to deflate.
>
> Anyone got an idea?
>
> Jim
> 83 FCRB
> Yorba Linda, ca
>
Already changed out the leveler valve with a new one, it made no
difference.
--- In
WanderlodgeForum@yahoogroups.com, "ac7880"
wrote:
>
> On the 83 Fc35 I owned previously, I had the exact opposite
problem.
> The rear air bags lost pressure in a couple of hours. In my case,
it
> was the two rear air leveler valves. I bought new ones from BB,
> problem solved.
>
> I may be your single air leveler valve, right in the middle by the
> front axle. Since it is under the coach, maybe you can't hear it,
> and if your jacks are down, it changes the leveler valve height
> setting.
>
> Dan
> NM 94 BB BMC 37'
>
>
>
> --- In WanderlodgeForum@yahoogroups.com, "bluebird3208"
> wrote:
> >
> > I have had a long standing problem of the front air bags
deflating
> > soon after the bus is parked. The bags will not hold overnight
and
> > sometimes that is all I need before leaving the next day. The
> jacks
> > work great but it is just one more thing to do. I have been all
> over
> > the bus. I have bubbled and sniffed (ultrasonic leak detector)
every
> > air leak I could find, and I am talking a detail inspection. The
> two
> > dry tanks will hold air for 2 weeks but the wet bleeds off way to
> > soon.
> >
> > Here is proof that even I get lucky sometimes. I have been
working
> > on the genset quite a bit lately and I just hook up an air line
> from
> > the workshop to the schrader on the wet tank and keep it full to
> > operate the gen air ram. I was in a hurry today to go to lunch
> with
> > my wife and tried to whip the air hose of the shrader valve and
> > snapped it off the air tank fill. All the air in the wet tank
> > dumped rapidly as I left for lunch. When I got back the front of
> the
> > bus is still at ride height. The only thing that makes sense to
me
> > is that I am some how getting pressure to the front dump valve
when
> > there is available air pressure in the wet tank causing the front
> > bags to deflate.
> >
> > Anyone got an idea?
> >
> > Jim
> > 83 FCRB
> > Yorba Linda, ca
> >
>
Jim,
I don't have my schematic in front of me but I think your hunch is
correct.
It does require air to dump the bags. Meaning, the dump valve itself
operates on air pressure. Therefore, perhaps the valve is leaking
when there's air pressure on it.
Otherwise, you could have a small leak in an airbag that you have not
noticed...yet. An ultrasonic leak detector is the best way to
determine this.
Gary Miller
83 FC 33 - For Sale
Milwaukee area
--- In
WanderlodgeForum@yahoogroups.com, "bluebird3208"
wrote:
>
> I have had a long standing problem of the front air bags deflating
> soon after the bus is parked. The bags will not hold overnight and
> sometimes that is all I need before leaving the next day. The
jacks
> work great but it is just one more thing to do. I have been all
over
> the bus. I have bubbled and sniffed (ultrasonic leak detector)every
> air leak I could find, and I am talking a detail inspection. The
two
> dry tanks will hold air for 2 weeks but the wet bleeds off way to
> soon.
>
> Here is proof that even I get lucky sometimes. I have been working
> on the genset quite a bit lately and I just hook up an air line
from
> the workshop to the schrader on the wet tank and keep it full to
> operate the gen air ram. I was in a hurry today to go to lunch
with
> my wife and tried to whip the air hose of the shrader valve and
> snapped it off the air tank fill. All the air in the wet tank
> dumped rapidly as I left for lunch. When I got back the front of
the
> bus is still at ride height. The only thing that makes sense to me
> is that I am some how getting pressure to the front dump valve when
> there is available air pressure in the wet tank causing the front
> bags to deflate.
>
> Anyone got an idea?
>
> Jim
> 83 FCRB
> Yorba Linda, ca
>
Jim,
There might be Clippard air/12v valves in your bus. On the PT they are
used to control lots of air stuff including inflating/deflating the air
springs. They are located behind the drivers side front panel, are the
dia. of a nickel and about 2" tall, yellow head, wires and 1/16" air
lines to/from them. They are mounted in two manifolds. check this link
http://www.clippard.com/store/byo_electr...efault.asp the very top
valve.
Call me if you would like me to stop by 269-6197.
Curt Sprenger
1987 PT38 8V92 "MacAttack Racing"
Anaheim Hills, Calif.
bluebird3208 wrote:
> Already changed out the leveler valve with a new one, it made no
> difference.
>
> --- In
WanderlodgeForum@yahoogroups.com
>
, "ac7880"
> wrote:
> >
> > On the 83 Fc35 I owned previously, I had the exact opposite
> problem.
> > The rear air bags lost pressure in a couple of hours. In my case,
> it
> > was the two rear air leveler valves. I bought new ones from BB,
> > problem solved.
> >
> > I may be your single air leveler valve, right in the middle by the
> > front axle. Since it is under the coach, maybe you can't hear it,
> > and if your jacks are down, it changes the leveler valve height
> > setting.
> >
> > Dan
> > NM 94 BB BMC 37'
> >
> >
> >
> > --- In WanderlodgeForum@yahoogroups.com
> , "bluebird3208"
> > wrote:
> > >
> > > I have had a long standing problem of the front air bags
> deflating
> > > soon after the bus is parked. The bags will not hold overnight
> and
> > > sometimes that is all I need before leaving the next day. The
> > jacks
> > > work great but it is just one more thing to do. I have been all
> > over
> > > the bus. I have bubbled and sniffed (ultrasonic leak detector)
> every
> > > air leak I could find, and I am talking a detail inspection. The
> > two
> > > dry tanks will hold air for 2 weeks but the wet bleeds off way to
> > > soon.
> > >
> > > Here is proof that even I get lucky sometimes. I have been
> working
> > > on the genset quite a bit lately and I just hook up an air line
> > from
> > > the workshop to the schrader on the wet tank and keep it full to
> > > operate the gen air ram. I was in a hurry today to go to lunch
> > with
> > > my wife and tried to whip the air hose of the shrader valve and
> > > snapped it off the air tank fill. All the air in the wet tank
> > > dumped rapidly as I left for lunch. When I got back the front of
> > the
> > > bus is still at ride height. The only thing that makes sense to
> me
> > > is that I am some how getting pressure to the front dump valve
> when
> > > there is available air pressure in the wet tank causing the front
> > > bags to deflate.
> > >
> > > Anyone got an idea?
> > >
> > > Jim
> > > 83 FCRB
> > > Yorba Linda, ca
> > >
> >
>
>
I had a problem simular this. I had to replace the Bendix DC4
valve. This valve is located on the drivers side inside frame rail
just above the back-front air bag. It's inline with the air-
compressor, located before the first air tank. The exhaust runs
under the dc4 valve and over the front airbags.
I had a leak in the flex pipe that caused extreme heat into the area,
destroying the *O* ring in the DC-4 valve. (also destroyed an air-bag)
This is a b*t*h to get to.
With this valve malfuntioning, the front of the coach would'nt rise
to the occasion. However the brakes aired up as did the rear air-
bags.
Hope this is of some help.
Harold Prescott
'85 FC35
Norhtern California
--- In
WanderlodgeForum@yahoogroups.com, "bluebird3208"
wrote:
>
> I have had a long standing problem of the front air bags deflating
> soon after the bus is parked. The bags will not hold overnight and
> sometimes that is all I need before leaving the next day. The
jacks
> work great but it is just one more thing to do. I have been all
over
> the bus. I have bubbled and sniffed (ultrasonic leak detector)every
> air leak I could find, and I am talking a detail inspection. The
two
> dry tanks will hold air for 2 weeks but the wet bleeds off way to
> soon.
>
> Here is proof that even I get lucky sometimes. I have been working
> on the genset quite a bit lately and I just hook up an air line
from
> the workshop to the schrader on the wet tank and keep it full to
> operate the gen air ram. I was in a hurry today to go to lunch
with
> my wife and tried to whip the air hose of the shrader valve and
> snapped it off the air tank fill. All the air in the wet tank
> dumped rapidly as I left for lunch. When I got back the front of
the
> bus is still at ride height. The only thing that makes sense to me
> is that I am some how getting pressure to the front dump valve when
> there is available air pressure in the wet tank causing the front
> bags to deflate.
>
> Anyone got an idea?
>
> Jim
> 83 FCRB
> Yorba Linda, ca
>
A fine example of the need to wrap the exhaust with header tape in
that area or some other type of heat shielding. There are other
critical items in there also such as the shifter cable, and throttle
cable.
It sounds as if you're describing the forward spring brake valve (the
one directly operated by the parking brake button - psssst). Been
there done that. I think it's supposed to also do some type of
proportioning of the air in the event of catastrophic air failure to
prevent an immediate lockup of the brakes, instead allowing a gradual
application. Failure modes (various leaks/various systems) of the
complex valve assembly are probably numerous when damaged by the heat.
Not sure it has much to do with the air suspension system however.
Other than the brakes need air first, then the accessories.
I've heard of some folks moving that valve to behind the airbags out
of danger and easier to work on. Not sure what science was applied
though since moving air valves and lines can disrupt the timing of
things in the brakes ever so slightly. It was easier for me to just
use heat shielding and header tape after changing the valve out. New
front airbags too (4).
Gary Miller
83 FC 33 - For Sale
Milwaukee area
--- In
WanderlodgeForum@yahoogroups.com, "Harold Prescott"
wrote:
>
> I had a problem simular this. I had to replace the Bendix DC4
> valve. This valve is located on the drivers side inside frame rail
> just above the back-front air bag. It's inline with the air-
> compressor, located before the first air tank. The exhaust runs
> under the dc4 valve and over the front airbags.
> I had a leak in the flex pipe that caused extreme heat into the
area,
> destroying the *O* ring in the DC-4 valve. (also destroyed an air-
bag)
> This is a b*t*h to get to.
> With this valve malfuntioning, the front of the coach would'nt rise
> to the occasion. However the brakes aired up as did the rear air-
> bags.
>
> Hope this is of some help.
>
> Harold Prescott
> '85 FC35
> Norhtern California
>
> --- In WanderlodgeForum@yahoogroups.com, "bluebird3208"
> wrote:
> >
> > I have had a long standing problem of the front air bags
deflating
> > soon after the bus is parked. The bags will not hold overnight
and
> > sometimes that is all I need before leaving the next day. The
> jacks
> > work great but it is just one more thing to do. I have been all
> over
> > the bus. I have bubbled and sniffed (ultrasonic leak detector)
every
> > air leak I could find, and I am talking a detail inspection. The
> two
> > dry tanks will hold air for 2 weeks but the wet bleeds off way to
> > soon.
> >
> > Here is proof that even I get lucky sometimes. I have been
working
> > on the genset quite a bit lately and I just hook up an air line
> from
> > the workshop to the schrader on the wet tank and keep it full to
> > operate the gen air ram. I was in a hurry today to go to lunch
> with
> > my wife and tried to whip the air hose of the shrader valve and
> > snapped it off the air tank fill. All the air in the wet tank
> > dumped rapidly as I left for lunch. When I got back the front of
> the
> > bus is still at ride height. The only thing that makes sense to
me
> > is that I am some how getting pressure to the front dump valve
when
> > there is available air pressure in the wet tank causing the front
> > bags to deflate.
> >
> > Anyone got an idea?
> >
> > Jim
> > 83 FCRB
> > Yorba Linda, ca
> >
>
Wow,
I typed, bendix DC-4 valve , into google and found more Bendix
air system info. than anyone would ever care to know, Lots of bedtime
reading..zzzzzzzzzzzzzzzz This could create a Forum Air System
Expert.
http://www.mybendix.com/AirbrakeHandbook.jsp
Bill 88 FC Michigan
--- In
WanderlodgeForum@yahoogroups.com, "Harold Prescott"
wrote:
>
> I had a problem simular this. I had to replace the Bendix DC4
> valve. This valve is located on the drivers side inside frame rail
> just above the back-front air bag. It's inline with the air-
> compressor, located before the first air tank. The exhaust runs
> under the dc4 valve and over the front airbags.
> I had a leak in the flex pipe that caused extreme heat into the
area,
> destroying the *O* ring in the DC-4 valve. (also destroyed an air-
bag)
> This is a b*t*h to get to.
> With this valve malfuntioning, the front of the coach would'nt rise
> to the occasion. However the brakes aired up as did the rear air-
> bags.
>
> Hope this is of some help.
>
> Harold Prescott
> '85 FC35
> Norhtern California
>
> --- In WanderlodgeForum@yahoogroups.com, "bluebird3208"
> wrote:
> >
> > I have had a long standing problem of the front air bags
deflating
> > soon after the bus is parked. The bags will not hold overnight
and
> > sometimes that is all I need before leaving the next day. The
> jacks
> > work great but it is just one more thing to do. I have been all
> over
> > the bus. I have bubbled and sniffed (ultrasonic leak detector)
every
> > air leak I could find, and I am talking a detail inspection. The
> two
> > dry tanks will hold air for 2 weeks but the wet bleeds off way to
> > soon.
> >
> > Here is proof that even I get lucky sometimes. I have been
working
> > on the genset quite a bit lately and I just hook up an air line
> from
> > the workshop to the schrader on the wet tank and keep it full to
> > operate the gen air ram. I was in a hurry today to go to lunch
> with
> > my wife and tried to whip the air hose of the shrader valve and
> > snapped it off the air tank fill. All the air in the wet tank
> > dumped rapidly as I left for lunch. When I got back the front of
> the
> > bus is still at ride height. The only thing that makes sense to
me
> > is that I am some how getting pressure to the front dump valve
when
> > there is available air pressure in the wet tank causing the front
> > bags to deflate.
> >
> > Anyone got an idea?
> >
> > Jim
> > 83 FCRB
> > Yorba Linda, ca
> >
>
Smokin' Brakeshoes Bill, that's far more than an
EXPERT would know about air brake systems, saavy
that to qualify for a Doctorate In Sheesh!-Sheesh!
Great find, thanks.
Hint: One can save .pdf files,print then, or make
your own tech library. Click on the diskette at the
top left, then save where you like.
Bob Janes, Greenville, SC
--- In
WanderlodgeForum@yahoogroups.com, "pattypape"
wrote:
>
>
> Wow,
>
> I typed, bendix DC-4 valve , into google and found more
Bendix
> air system info. than anyone would ever care to know, Lots of
bedtime
> reading..zzzzzzzzzzzzzzzz This could create a Forum Air System
> Expert.
>
> http://www.mybendix.com/AirbrakeHandbook.jsp
>
> Bill 88 FC Michigan
>
>
>
>
>
> --- In WanderlodgeForum@yahoogroups.com, "Harold Prescott"
> wrote:
> >
> > I had a problem simular this. I had to replace the Bendix DC4
> > valve. This valve is located on the drivers side inside frame
rail
> > just above the back-front air bag. It's inline with the air-
> > compressor, located before the first air tank. The exhaust runs
> > under the dc4 valve and over the front airbags.
> > I had a leak in the flex pipe that caused extreme heat into the
> area,
> > destroying the *O* ring in the DC-4 valve. (also destroyed an air-
> bag)
> > This is a b*t*h to get to.
> > With this valve malfuntioning, the front of the coach would'nt
rise
> > to the occasion. However the brakes aired up as did the rear air-
> > bags.
> >
> > Hope this is of some help.
> >
> > Harold Prescott
> > '85 FC35
> > Norhtern California
> >
> > --- In WanderlodgeForum@yahoogroups.com, "bluebird3208"
> > wrote:
> > >
> > > I have had a long standing problem of the front air bags
> deflating
> > > soon after the bus is parked. The bags will not hold overnight
> and
> > > sometimes that is all I need before leaving the next day. The
> > jacks
> > > work great but it is just one more thing to do. I have been
all
> > over
> > > the bus. I have bubbled and sniffed (ultrasonic leak detector)
> every
> > > air leak I could find, and I am talking a detail inspection.
The
> > two
> > > dry tanks will hold air for 2 weeks but the wet bleeds off way
to
> > > soon.
> > >
> > > Here is proof that even I get lucky sometimes. I have been
> working
> > > on the genset quite a bit lately and I just hook up an air line
> > from
> > > the workshop to the schrader on the wet tank and keep it full
to
> > > operate the gen air ram. I was in a hurry today to go to lunch
> > with
> > > my wife and tried to whip the air hose of the shrader valve and
> > > snapped it off the air tank fill. All the air in the wet tank
> > > dumped rapidly as I left for lunch. When I got back the front
of
> > the
> > > bus is still at ride height. The only thing that makes sense
to
> me
> > > is that I am some how getting pressure to the front dump valve
> when
> > > there is available air pressure in the wet tank causing the
front
> > > bags to deflate.
> > >
> > > Anyone got an idea?
> > >
> > > Jim
> > > 83 FCRB
> > > Yorba Linda, ca
> > >
> >
>