TargetTalk

My Wife and I both have a LP 400 Carbon, which we both love, however we are now having problems when trying to fill the cylinder. It appears the o' ring on the inlet of the cylinder has worn and leaks when filling off the dive tank. I contacted Frontier Arms in Aus , who didn't offer any assistance or suggestion or offer of Warranty replacement as one of the cylinder is dated 07/14. Pretty poor service from a long time Walther Distributor.
Does anyone know if or how to replace that O'ring?.

The old O-ring can be removed with a dental/O-ring pick, that's the easy part. You need to either find an OEM replacement, or a suitable seal of the same size. McMaster-Carr has a really good selection.

http://www.mcmaster.com/#o-rings/=wub3vf

Walther does not list any tank parts or seals at all, only complete tanks.
Also try emailing Walther for the seal sizes.
Remove the old seal to match it,for an Australian source try CBC bearings.
http://www.conbear.com/files/content.ph ... gs&lang=en

Are you in Australia ??, if yes then try Potter firearms.
When you say your cylinder leaks when filling off the dive tank , does it leak once filled and on the pistol , if not, then it is not your cylinder that is leaking, but the o,ring on your fill adapter attached to your dive tank .
Do you have a regulator/bleed valve attachment on your tank or are you just filling off the adapter attached to the dive tank.
If you are not bleeding the cylinder before you remove from the tank ,then it the pressure when you unscrew your cylinder that is blowing your seal.
post a picture of your tank set up,
Cheers, S

Edit above :
just had a look at Walther site and it doesn't list any O-rings for your cylinder , but it must have one internal , I would be chasing up the dealer where you bought it , especially if it was from Frontier Arms in Australia ,they are the distributors .
There will be several shooters on this forum that will shoot the lp400 , you may just have to wait a few days

I too have had the same problem on some but not all cylinders, or valves.

I believe that the adaptor cant screw into the threads of far enough on some DIN style K valves and therefore the o ring on the rear of the adaptor wont seal against the rear face of the K valve and the air leaks past the threads. My Steyr adaptor does not have this problem.

To fix this I made another washer/spacer with a wad punch from about some 3mm thick rubber and drilled a new hole in the centre. This I place inside the K valve of the dive tank and then thread in the adaptor. Not sure why this only happens on some valves. However my fix has worked. Simples.

Jeremy K wrote:Not sure why this only happens on some valves.

The normal reason would be that you have a 232bar adaptor and a 300bar valve.

The threads on 300bar are longer as a safety measure to prevent someone connecting a lower pressure item (like most airgun cylinders) to a higher pressure supply.

The washer will not correct from a 232 DIN to a 300 DIN there is 10mm difference in length.
The 232 bar DIN connections have 5 threads (25mm long) and 300 bar DIN connections have 7 threads (35mm long) [5/8” 14TPI BSP].
I found this problem of the adaptor leaking only on some 232 DIN fittings but not others and it was not the overall length.
It was the reduced end of the Walther fill adaptor was oversize to the recess seat of the DIN valve, by turning about .015" off the overall diameter
from the adaptor (spigot end with O ring) it allowed the adaptor to fully seat into all the DIN fittings.

I stand corrected.

Got me a little confused here David M.

I have 232 bar K Valve. The only way I can use the Walther adapter is with the washer in place. I have not tried it on a 300 bar yet that I know of.

Are you saying you removed some thickness off the end of the adaptor after the threads? Therefore making the wall thickness that keeps the o ring in place thinner?

Would you have any pictures of where you removed material from?

Cheers J.

yes, I reduced the diameter by .015", it still leaves enough
for the O ring and the adaptor now seats better.
After screwing your adaptor into the DIN valve, gently load
it with a spanner and see if it has any further movement.
Then remove it and have a real good look at the corner
edge of the adaptor for any marks or damage.
I found my adaptor had marks from interference.

Thanks to all of you for your helpful hints on fixing this problem.
I need to commend Ulrich from Walther DE who replied with an offer of new seals within a couple of hours, now that is good service. I got a black washer similar in size to a tap washer from JK and that did work, although it's a solution that we should have to resort to. It does indicate the problem is the cylinder O'ring not sealing on the adapter.
I measured the diam at the unthreaded section of the adapter which was 6.68mm, the same section on the pistol where the cylinder screws onto measured 6.64, a difference of 0.06mm.
If the O'ring was on the adapter instead of inside the cylinder inlet, it would be a much easier fix as is found on the Steyr filling adapter.