Schemp Hirth water ballast dump valves

The dump valve on my Nimbus 3 are leaking - one leaks about 10 litres
overnight, another 10 litres an minute, the others somewhere in between.
I'm looking for help on how to go about sealing them better.

I will get some new springs manufactured to push the valves closed but I
would appreciate help on how to renew / refurbish or repair the existing
seals themselves.

Tkx
Ian

You are using some sort of wax sealing agent at the
valve? I use Carmex, others use Chapstix...and I am
sure other products work well. Also you are pulling
the valve tight with the rigging tool? Only thing
else I can think of is to work the dump actuating lever
to free up the linkage.



At 06:48 01 September 2004, Tango4 wrote:
The dump valve on my Nimbus 3 are leaking - one leaks
about 10 litres
overnight, another 10 litres an minute, the others
somewhere in between.
I'm looking for help on how to go about sealing them
better.

I will get some new springs manufactured to push the
valves closed but I
would appreciate help on how to renew / refurbish or
repair the existing
seals themselves.

Tkx
Ian

Ian,
Your Nimbus 3 has internal springs that have long since
rusted off (part of the problem) and there is no practical
way to replace them because that involves opening up
the wing. I added stronger external springs that apply
more torque to the dump shaft (s) , one on the inboard
and another on the outboard, as I remember. Then I
would goop up the dump valves with chap-stick, insert
the 6mm tool and pull down with a half twist. That
seemed to do the trick. In real hot weather I would
use very heavy wax, the stuff that your toilet bowl
sits on.
JJ

Ian

Take a minute and determine how the valves are leaking. If the H2O is
dripping around the edge of the plug then this is completely normal
and can be fixed easily. Buy a tube of lip balm (Chapstick in USA)
open the valves and put a good coating around inside the wing on the
lip were the metal plug seats in the opening. Then close the valves
with a snap and your leak is no more. Do not use grease as it washes
away and is a mess. If they still drip a little use the red tail pin
removal tool to seat the plugs by screwing it into the bottom of the
plugs and pulling a bit to seat them. After a few treatments you will
be leakless all summer.

If the valves are leaking past the root wing rib into the cockpit area
then it may be a corrosion problem with the water ballast control rod
that drives the valves - and that is a bigger, more expensive problem.

John Seaborn
Ventus 2b
USA



"tango4" wrote in message ...
The dump valve on my Nimbus 3 are leaking - one leaks about 10 litres
overnight, another 10 litres an minute, the others somewhere in between.
I'm looking for help on how to go about sealing them better.

I will get some new springs manufactured to push the valves closed but I
would appreciate help on how to renew / refurbish or repair the existing
seals themselves.

Tkx
Ian

Ian:

Before filling mine I lock open the 4 dump valves and swab the inside of =
the valve orifice with a q-tip dipped in vasoline. Then close, pull with =
the tool & fill.

Observe for any drips. If you see any gently rub some vasoline into the =
rim of the valve (without pressing up too hard).

I've noticed that after I do this a few times - I can skip the first =
step for a few flights.

Roy B.

The toilet bowl wax idea JJ talks about works great -- but as he states you
have to use the tail rigging tool to pull the plugs down firmly into the seat
(sqeezing the excess wax out of the seat). With properly seated valves (see
below) this makes for zero leakage over the entire day.

I also have a nimbus 3t and had to repair/replace the INTERNAL parts on one of
my dump valves (broken/bent actuating bolt that was badly corroded). To do that
repair the external and internal spring need to be removed, parts replaced and
then the whole assembly rebuilt. Everyone said that rather large holes would
need to be cut into the wings to do this -- NOT TRUE. By removing the pushrod
seal/boot you can gain access to the internal spring & dump valve components
thru the wing root.

I decided to replace all of my internal springs at the time the repair was
being done to the one bad valve. An e-mail to Biggo @ Schempp-Hirth was the
solution to my problems. I ordered all the parts needed from him to replace
the internal /external springs and discussed the repair to be made. In
addition to sending me the ordered parts, he include photos of a nimbus 3 wing
opened up into halves and showing all the internal parts, how the went together
and how to specifically replace the internal springs. I could have kissed him
for those photos showing how to make the repair. He also very kindly sent me a
simple/crudley made tool used to remove / re-install the intenal springs at no
charge. I can't speak highly enough of Biggo @ Schempp-Hirth for how I have
been treated on numerous occasions. Because I was reparing the actual dump
valve mechanism I also needed a long handled open ended wrench (to reach inside
the wing to the parts). I had a local welder add an flat extension to a normal
open ended wrench.

If you need more access to the internals than that (you will not if only
replacing the interanal springs with the factory rigging tool) you can remove
the aluminum dumb valve plug itself by drilling 2 very small holes into the
aluminum plug -- then put safety wire thru those holes (for leverage) and
turned the plug off the bolt. Then you can access the entire mechanism thru 2
locations (wing root push-rod seal and open dump valve hole). After ALL your
repairs are made, use the safety wire to screw the alum plug back on (take the
time to space it at the right height for a good, flat seal --we "shimmed it"
using 2 nuts on the new stainless steel bolt above the plug) and seal the small
holes in the alum plug with silicon. Then use the tool to re-install the new
internal springs, reinstall the wing root boot/seal, reinstall the external
springs and test the system.

My suggestion is to order the parts you need from Biggo and specifically ask
for the zerox copies of those open wing photos. The repair is not hard to do
and can be done in part of a weekend day if you have a shop with saw horses
available. You have to be careful of the rubber boots/bellows on the wing root
seal becasue old ones can be a bit fragile -- but M & H Soaring stocks them if
you accidently rip one. If you need to borrow the special tool Biggo gave me, I
am willing to loan it out -- but you will have to promise to return it to me.

I hope this helps you and good luck.

Steve McLaughlin (PSU)

Ian,

I may not be offering any new information here, but let me suggest the
following. Clean the sealing surfaces, then close and very lightly
seat the valves with your bolt-knob. Before putting in any water, take
a chap stick and apply fenerously around the edges of the seal. While
the wings are filling, work any excess into leak points along the seam
gently with your fingers, being careful not to unseat the valve. I've
had success with this... much more so than applying chap stick,
vaseline, and other sealants to the surfaces before closing. After a
few such applications, you shouldn't need to seat valve, assuming
there is ample tension in the closing mechanism.

"tango4" wrote in message ...
The dump valve on my Nimbus 3 are leaking - one leaks about 10 litres
overnight, another 10 litres an minute, the others somewhere in between.
I'm looking for help on how to go about sealing them better.

I will get some new springs manufactured to push the valves closed but I
would appreciate help on how to renew / refurbish or repair the existing
seals themselves.

Tkx
Ian

For me it works excellent to just smear some vaseline between the seat
and the valve. After that I use the schemmp-hirth tailplane mounting
tool to firmly pull the valve against the seat (there is a 6mm
threaded hole in bottom of the valves which I believe is there exactly
for this reason).

Regards
/ Jan Larsson
Mini Nimbus C #121
Sweden

I hope I'll never need it but I'll keep a copy of this
posting.

Are there any ways of preventing corrosion in the internal
actuating components - other than keeping the tanks
dry as much as possible?

John Galloway


At 15:48 01 September 2004, Psusoar wrote:
The toilet bowl wax idea JJ talks about works great
-- but as he states you
have to use the tail rigging tool to pull the plugs
down firmly into the seat
(sqeezing the excess wax out of the seat). With properly
seated valves (see
below) this makes for zero leakage over the entire
day.

I also have a nimbus 3t and had to repair/replace the
INTERNAL parts on one of
my dump valves (broken/bent actuating bolt that was
badly corroded). To do that
repair the external and internal spring need to be
removed, parts replaced and
then the whole assembly rebuilt. Everyone said that
rather large holes would
need to be cut into the wings to do this -- NOT TRUE.
By removing the pushrod
seal/boot you can gain access to the internal spring
& dump valve components
thru the wing root.

I decided to replace all of my internal springs at
the time the repair was
being done to the one bad valve. An e-mail to Biggo
@ Schempp-Hirth was the
solution to my problems. I ordered all the parts needed
from him to replace
the internal /external springs and discussed the repair
to be made. In
addition to sending me the ordered parts, he include
photos of a nimbus 3 wing
opened up into halves and showing all the internal
parts, how the went together
and how to specifically replace the internal springs.
I could have kissed him
for those photos showing how to make the repair. He
also very kindly sent me a
simple/crudley made tool used to remove / re-install
the intenal springs at no
charge. I can't speak highly enough of Biggo @ Schempp-Hirth
for how I have
been treated on numerous occasions. Because I was
reparing the actual dump
valve mechanism I also needed a long handled open ended
wrench (to reach inside
the wing to the parts). I had a local welder add an
flat extension to a normal
open ended wrench.

If you need more access to the internals than that
(you will not if only
replacing the interanal springs with the factory rigging
tool) you can remove
the aluminum dumb valve plug itself by drilling 2 very
small holes into the
aluminum plug -- then put safety wire thru those holes
(for leverage) and
turned the plug off the bolt. Then you can access
the entire mechanism thru 2
locations (wing root push-rod seal and open dump valve
hole). After ALL your
repairs are made, use the safety wire to screw the
alum plug back on (take the
time to space it at the right height for a good, flat
seal --we 'shimmed it'
using 2 nuts on the new stainless steel bolt above
the plug) and seal the small
holes in the alum plug with silicon. Then use the
tool to re-install the new
internal springs, reinstall the wing root boot/seal,
reinstall the external
springs and test the system.

My suggestion is to order the parts you need from Biggo
and specifically ask
for the zerox copies of those open wing photos. The
repair is not hard to do
and can be done in part of a weekend day if you have
a shop with saw horses
available. You have to be careful of the rubber boots/bellows
on the wing root
seal becasue old ones can be a bit fragile -- but M
& H Soaring stocks them if
you accidently rip one. If you need to borrow the special
tool Biggo gave me, I
am willing to loan it out -- but you will have to promise
to return it to me.

I hope this helps you and good luck.

Steve McLaughlin (PSU)

The standard method to close the leaking seals is rubbing vasoline over the
valves into the leaking gap. In this way the vasoline works as an additional
sealing. Works great but must be repaeted about every time the tanks are
filled with water.

Karel, NL



"tango4" schreef in bericht
...
The dump valve on my Nimbus 3 are leaking - one leaks about 10 litres
overnight, another 10 litres an minute, the others somewhere in between.
I'm looking for help on how to go about sealing them better.

I will get some new springs manufactured to push the valves closed but I
would appreciate help on how to renew / refurbish or repair the existing
seals themselves.

Tkx
Ian