Why not

rgogan

New member
Sep 20, 2004
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After rebuilding my rotary height control valves this spring, I was initially disappointed that my air springs were still leaking down. When I pulled
the valves out of the dash and soap tested them, they had a slow leak around the newly installed housing seals.
I torqued down the Allen screws and was delighted to see an airtight result. I had not cranked on the Allen bolts too hard previously because they
seem somewhat delicate and the instructions warned about overtorqueing. The result was great!! The air springs have kept the coach up all summer.
First time in 30 yrs of coach ownership that this has happened.
However, today while driving, there was a loud pop that came from the passenger side rotary air valve and a loud whine of air leaking. I made it home
before the suspension flattened out completely.
At home, I discovered that the top piston had been blown out of the bore towards the plastic valve. I though this was no supposed to happen as it is
retained by the rubber O ring on the spring side of the piston. The piston that was displaced out of the bore was inspected under the microscope.
Both rubber O ring seals were in place and not damaged. The housing was inspected from outside and I could see no cracks. I thought I might have
overtorqued the Allen screws and cracked the housing. Will have to disassemble the housing and see if there are internal cracks.
My suspicion however is that the replacement O ring that goes on the spring side of the piston was undersized or not hard enough to prevent the air
pressure from blowing the piston, that it was supposed to retain, out the front of the housing. Has any one else encountered this problem and come up
with a solution?
Bob Gogan
 
The solution: Power Level II valves from JR Slaten. Not cheap, but a
permanent solution with vastly better quality internals.

http://www.appliedgmc.com/prod.itml/icOid/738

Rick "who did this years ago and never looked back" Denney

On Sun, Sep 17, 2017 at 8:12 PM, Robert J. Gogan
wrote:

> After rebuilding my rotary height control valves this spring, I was
> initially disappointed that my air springs were still leaking down. When I
> pulled
> the valves out of the dash and soap tested them, they had a slow leak
> around the newly installed housing seals.
> I torqued down the Allen screws and was delighted to see an airtight
> result. I had not cranked on the Allen bolts too hard previously because
> they
> seem somewhat delicate and the instructions warned about overtorqueing.
> The result was great!! The air springs have kept the coach up all summer.
> First time in 30 yrs of coach ownership that this has happened.
> However, today while driving, there was a loud pop that came from the
> passenger side rotary air valve and a loud whine of air leaking. I made it
> home
> before the suspension flattened out completely.
> At home, I discovered that the top piston had been blown out of the bore
> towards the plastic valve. I though this was no supposed to happen as it is
> retained by the rubber O ring on the spring side of the piston. The
> piston that was displaced out of the bore was inspected under the
> microscope.
> Both rubber O ring seals were in place and not damaged. The housing was
> inspected from outside and I could see no cracks. I thought I might have
> overtorqued the Allen screws and cracked the housing. Will have to
> disassemble the housing and see if there are internal cracks.
> My suspicion however is that the replacement O ring that goes on the
> spring side of the piston was undersized or not hard enough to prevent the
> air
> pressure from blowing the piston, that it was supposed to retain, out the
> front of the housing. Has any one else encountered this problem and come up
> with a solution?
> Bob Gogan
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com
 
The same thing happened to me several time. The first time I didn't have
the plastic dial on and that piston came shooting out at me. Took a while
to find it, it had hit a plastic bin on the couch and ended up inside the
bin.

Mine don't leak at the valves anymore, but the T junction behind the drive
side one. I did adjust the tank pressure in my holding tank, I know it was
over 120psi (didn't let it get over 120 to find what it was stopping at),
now it's at 110-115psi. But I don't trust it to drive with it on, I
manually adjust the bags to around 80-90psi and use the cutoff at the
bags. I've given up on the old dials, just saving up money to replace them
with the JR Slaten ones and the run new lines.

--
Ethan James
Roanoke, VA
76' Glenbrook

On Sun, Sep 17, 2017 at 8:13 PM Robert J. Gogan
wrote:

> After rebuilding my rotary height control valves this spring, I was
> initially disappointed that my air springs were still leaking down. When I
> pulled
> the valves out of the dash and soap tested them, they had a slow leak
> around the newly installed housing seals.
> I torqued down the Allen screws and was delighted to see an airtight
> result. I had not cranked on the Allen bolts too hard previously because
> they
> seem somewhat delicate and the instructions warned about overtorqueing.
> The result was great!! The air springs have kept the coach up all summer.
> First time in 30 yrs of coach ownership that this has happened.
> However, today while driving, there was a loud pop that came from the
> passenger side rotary air valve and a loud whine of air leaking. I made it
> home
> before the suspension flattened out completely.
> At home, I discovered that the top piston had been blown out of the bore
> towards the plastic valve. I though this was no supposed to happen as it is
> retained by the rubber O ring on the spring side of the piston. The
> piston that was displaced out of the bore was inspected under the
> microscope.
> Both rubber O ring seals were in place and not damaged. The housing was
> inspected from outside and I could see no cracks. I thought I might have
> overtorqued the Allen screws and cracked the housing. Will have to
> disassemble the housing and see if there are internal cracks.
> My suspicion however is that the replacement O ring that goes on the
> spring side of the piston was undersized or not hard enough to prevent the
> air
> pressure from blowing the piston, that it was supposed to retain, out the
> front of the housing. Has any one else encountered this problem and come up
> with a solution?
> Bob Gogan
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>