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)