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Tuning Slow air leak in FX Impact II

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Davee

Davee

Member
Jul 27, 2018
17
0
Washington
Before I send my gun to Utah I wanted to know any possible solution I can do myself. I would like to be more comfortable with hands on fixing my Impact.
When I got my Plenum upgrade I asked this to be checked and I was told they did.but only for a comparatively short time period.
After sitting with the Impact II decocked for a period of 2 weeks or more, the bottle and regulator gauges will fall to near “0”.

I have taken CRC spray and followed the suggestions in the FX Masterclass video as to possible sources of leaks with no success.

Does anyone have a suggestion? I reached out via PM to Ernest but have not heard back as yet.

Thank you for taking your time to read this.

Dave E
 
Sneaky slow leaks are the worst.

Did you already check for a leak at the regulator vent hole? Clear tape over the hole, see if it lifts.

What about a slow leak from the poppet? Balloon over the muzzle (actual muzzle, not the end of the shroud). Bolt closed to seal the other end.

Beyond that, it’s time to roll up your sleeves. For bottle guns, I like to start by removing the bottle and dunking the bonnet in a glass of water and look for bubbles. There are as many as 9 places a bottle can leak so many times that reveals the problem with a minimum of effort. Same concept applies to models that have a modular air tube & valve assembly (e.g. some Hatsan models like the AT44)

If not, then I take the rifle and off comes everything that’s either not pressurized or serving some safety function to retain the pressurized stuff. Into the bathtub it goes.

Would I like to avoid that? Absolutely. But the cumulative time and effort to avoid it is usually well in excess of just accepting the reality that the situation stinks and the best way is to face it head on. This way you can know in a matter of minutes what’s wrong. No guesswork, no uncertainty, no pointless O-ring replacement crusades, no futile PTFE tape replacement. Just a leak sheepishly raising its hand to say “here”. 
 
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# then I take the rifle and off comes everything that’s either not pressurized or serving some safety function to retain the pressurized stuff. Into the bathtub it goes.

That's what CHUCK did to my Impact on a super slow leak, I mean like a bar in a week. It took over a minute for the bubble to come to the surface. You should just do it and not go crazy looking for the leak.
 
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I was having a similar problem. Ended up leaking out the barrel. So I put the stock plenum back on and leak stopped. Upon inspection it appears that the valve seat is worn or not machined well. The stock plenum has a seat that presses into the housing. FX is sending me new parts but I may just leave the stock plenum installed. Don’t be afraid to tear apart as it is not that difficult. 

 
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A plenum upgrade can mean a new valve body is installed with your old worn valve pin. Even if the two parts are both new they may not seal perfectly at first. Put a balloon or seal a rubber glove over your barrel to check for leakage there. If you find a leak and you spend some time shooting it it may blow any debris out or form to the new valve pin to the valve body and stop the leak otherwise the pin seal is part # B27 or B28 depending on your caliber. Although you may want the whole assembly as locktight is applied to the parts and heat may be needed to get them apart.

The valve body, new ones have the valve seat machined into them, may not be machined just right as well so that would cause a leak there also.

https://fxairguns.com/wp-content/uploads/2020/07/Impact-MkII.pdf

Scroll down for parts and part #'s
 
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The bathtub technique may sound scary but it is the fastest, easiest way to find a slow leak If detect-a-leak doesn’t work. Slow leaks are the worst!!! If mine is 1-3bar a night, I don’t even worry about it. Anything more, two options...Change all the o-rings where it could leak or dunk it in the bathtub! I start with the o-rings which usually works and then go for the dunking.

Stoti
 
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