DIY fix: Leaking fill valves

[jordan7831]

Hello everyone,

TL;DR version in post 2.

Have you ever had mags that dont leak but spew out propane everywhere when you fill them? Many mags from companies like KJW, WE ect have ridiculously small o rings on the fill valves that help prevent gas from leaking when they are filled. These are known as silent fill valve o rings.

However, these O rings often dry up, fall out, or just get worn down after being filled multiple times. Some mags don't even have silent fill valve O rings. For instance, many TM mags I have lack this small O ring. As a result, filling them becomes a pain and wastes gas.

I've recently decided to make a shift to a pistol only platform, and had a score of TM MEU mags. However, much to my dismay they all had the same problem. The mags would spew gas when filling. They did not leak at all, but only held enough gas for about 15 shots. This falls far short of the 25 BB capacity of these mags (yes I know they hold more but I load up to 25 in mine).

So I began searching and searching for O rings. In my research I found several options.

1. Buy from Mcmastercar - Unfortunately they decided not to ship to individuals in Canada and only deal with businesses. They do however carry correct sized O rings and cost about $3 for a pack of 100. Very cheap if you can score some.

2. Scourer every hardware store I can find - No one sells o rings this small. I didn’t try any hydraulic supply stores but that is an option too.

3. Buy some expensive O rings from airsoft stores or ebay - at $8 for 15 O rings this is a rip off but viable if you need them, and known to work.

4. Break open every lighter you can for the small o rings inside - This does work, and is easy if you know lots of smokers. I was able to salvage about 2 o rings from every lighter I found. But is wasteful and a pain if you have lots of mags to service.

So here were the options I tried. Salvaging lighter parts proved the most successful so far. A few lighters I found had small rubber tubes which could be cut and used to service several mags. I managed to fix 6 mags with one lighter.

But then I had a thought. As I was thinking to myself "where have I found small o rings before?" Then I got a reminder about a dental appointment and it hit me. The small elastics that are used for braces are super small and might be just what I need.

So fast forward a week and I finally found a solution to my leaky mags.

These are the elastics from the dentist. They are made by 3M.


Here is an o ring salvaged from a lighter. Notice how small it is. They only measure 2.87mm in diameter. These o rings are known to work perfectly with my TM mags.


Here is the elastic from my dentist. The diameter is 2.81. Very close to the same size.


A couple pictures next to a ruler. Metric and imperial for those who use the old school system. O rings are mainly measured using the imperial system so this helps I guess.



Installation is super easy. Simply place the o ring on the fill valve. Leave those stupid pens and toothpicks alone. They are not needed. Ive seen several tutorials on how to install these and I don’t know why everyone feels the need to struggle with toothpicks trying to push the o ring on.


To install, ensure the o ring is centered on the fill valve. Take your propane adapter and simply push the o ring down with the adapter. The adapter ensures the o ring goes on evenly. It's best to empty your mags of any gas before doing so. But if you are lazy, simply place your finger firmly on the hole in the adapter to prevent gas from escaping. Push down, look to make sure the o ring is seated, and push several more times to get it to the bottom. Not necessary, but ensures a solid fit.


Now test to ensure the mag no longer leaks when being filled, and fully load up a mag with BBs to verify you can get a whole mag.

The gas efficiency for my TM mags went from 15 rapid shots to being able to empty a full mag. I re-gas after every mag so I'm not concerned about how many shots per mag I can get. As long as I can empty my mag I am happy.


Addendum:
Lets say what ever o rings you get doesn't work and prevents the propane adapter from fully depressing the fill valve. This could be caused by having an o ring that is too thick, necessitating the removal of the o ring.

In my trial and error I have found a very simple way to remove the fill valve o rings. Rather than prying it out with a toothpick or small screw driver and damaging the fill valve. Your propane adapter can easily remove it. The saying "I brought you into this world and I can take you out" comes to mind.

So to remove an o ring simply gas the mag up slightly. Now remove the propane adapter and press down on the fill valve with it. The trick is to misalign the adapter causing gas to rush out of the fill valve. The gas pressure will force the o ring off the valve allowing for easy removal.

Alternatively, you can also use a cue tip broken in half. The soft cardboard will not damage the valve.


Here is a video about silent fill valve o rings. He also sells them on his ebay page.
How to install Silent Fill o-ring in hi-capa - YouTube

If you can buy from McMastercar here is the link and size to order:
i will gladly give money to the first ATOTer who can tell me where to find o-rings... - AnandTech Forums

http://www.c3airsoft.com/showthread....ill-25481.html


Size: AS568A - 002

Fractional:
Width 3/64
ID 3/64
OD 9/64

Actual inch size:
ID .042"
OD .142"

Redwolf article:
http://www.redwolfairsoft.com/redwol...il?bulletID=50

Thanks for reading.

[jordan7831]

TL; DR Version.

Fix your fill valves. Go to the dentist and mooch some of the small elastics they use for braces. Stick them in using propane adapter. Mags leak no more when filled.

Or buy some cheap lighters, you should get 2 o rings from each lighter.

[coach]

Meh, a little gas spraying out when I fill my TM mags isn't such a terrible thing.

[ccyg8774]

Got a O-ring kit for $1.00 from dollar store, not sure if these small ones are right sized though.

I got the kit mostly for the larger ones anyway.

[Styrak]

There's a reason why TM mags are not silent fill. There is a two way valve that prevents overfilling.

[jordan7831]

Good point Stryak. But some mags I have were so bad that I could only get less than 10 shots. Some hicapa ones were like that until I fixed them.

Ill have to hit up a dollar store next ccyg8774. Thanks for the suggestion!

[Sequential]

Originally Posted by ccyg8774

Got a O-ring kit for $1.00 from dollar store, not sure if these small ones are right sized though.

I got the kit mostly for the larger ones anyway.

Dollarstore has this kit, for $1.

I've been using them for the fill valves for awhile now. So far so good !

[jordan7831]

Any dollar store in particular?

[ccyg8774]

Originally Posted by jordan7831

Any dollar store in particular?

I got mine from the "Great Canadian Dollar Store". Other silimar stores like A Buck or Two or Dollarama may also have it.

[Sequential]

Originally Posted by jordan7831

Any dollar store in particular?

Dollarama doesn't have them, you need to go to those buck or two in bridlewood mall or something.

[jordan7831]

Dammit, there are ONLY dollaramas around me!

[Stealth]

Alright I found them on McMaster, now which one am I supposed to get?
Viton?
Silicone
Buna-N?
Neoprene?

[Azathoth]

@Stealth

Viton or Buna-Nitrile


What is the Part number at Mcmaster-Carr? I need some PTW O rings and i'll piggy back some of these on my order.

[lurkingknight]

http://www.efunda.com/designstandard...one&SC=Propane

according to that, either silicone, neoprene or buna N

[jordan7831]

Originally Posted by Stealth

Alright I found them on McMaster, now which one am I supposed to get?
Viton?
Silicone
Buna-N?
Neoprene?

Buna are the ones that were recommended in this thread.

http://www.c3airsoft.com/showthread....ill-25481.html

The part number is AS568A - 002

If you order some, Id like to piggy back too if thats alright. I wouldnt mind 100 spares.