Tuning Fx impact M3 slow leak (fixed).

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Tyler907

Tyler907

Member
Feb 6, 2022
11
1
Alaska, United States
Hi everything,

just received my fx impact m3 .30 sniper and put air in it again last night as it shipped to Alaska with 50 bar in the air tank for the plane ride here. Filled to 250 bar with a brand new nomad 2. Woke up this morning and the gun is at 230 bar now. Have done this 2 days in a row has it’s dark by the time I get home from work. Been looking on here for a good place to start looking for a slow leak. Any info would be greatly appreciated. Hate to send the gun back as to Alaska shipping as been a pain lately with everything going on in the world. Don’t normally get very irritated with things like this but for the money just seems ridiculous. I bought the gun from ua who were awesome to deal with. Been out of the game since 2014 when I bought an fx royal 500 and never had 1 issue. What is the best way to look for the leak soapy water around screw girls and tank threads and such?
 
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So, did you wait for the tank to cool down first before you looked at the pressure gauge? You will loose 10 to 20bar after the tank cools from the fill. Most just fill it over a bit or wait till it cools down and top it off.

I have had a couple of leaks on my Impacts. Both have been at the gauges and only required me to snug them up a tiny amount to stop the leak. The other leak I had was from me damaging an o-ring when I had the gun apart for an upgrade.

Yes, soapy water or a leak detector product will werq a bit better but likely you see the leak either way.

Edit;

I used to use an eyedropper or syringe for the soapy water so it did not get where I didn't want it to be. I have since graduated to a store bought leak detector.
 
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If you just filled it. Expect it to go down a few bars when it cools down. Wait a day, see where its at. Then check again tomorrow and see if its still at the same spot or have it down. Thats how you know if its actually leaking. When my impact leaked, it was at the guages and reg. Tighten the guages and removed the reg, cleaned it and put it back in. Everything been good since.
 
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Experienced people say that soapy water will cause rusting issues, and recommend proper leak detection fluid that won't do that. I bought a bottle but haven't had to use it yet.

The easiest places to start checking are probably the atmosphere holes for the two regs, the grub screw plugging the supply hole for angled manometer bracket, and the foster fitting (check valve not working). Atmosphere hole on first reg is on the bottle adapter, and for the second reg, its the hole on right side of gun where the angled manometer bracket would go. Grub screw sealing angled manometer bracket supply hole is next to the atmosphere hole. I haven't done it, but you may be able to put some tape over those spots and see if it gets pushed off.

*Note about that grub screw sealing - Factory method I believe is to attempt seal without anything else and if that fails, put a small piece of cut oring in the bottom of the hole and reinstall the grub screw. On my M3 I had something crazy happen where the oring chunk got sucked into passageway downstream of second reg and cause slow plenum refresh.

I feel where you are at right now with not wanting to ship it, and also not wanting to be without it. If I was in your shoes, I'd pickup leak detection fluid and see if I could figure out where the leak is, then watch some videos on getting to that part of the gun. Most of the leak spots are pretty easy to get at and work on, even the regs. If the leak is in the valve/plenum area, that requires near complete disassembly of the gun. If your leak is in a spot you think you can handle, FX will send you the parts for free. They will also pay to have it shipped back if that is the route you want to take. They may even be OK with you trying and sending it to them in the event you do not succeed - just ask them first.
 
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E70DE3BC-DD7B-470C-9B4E-C4E4BD8C1BCA.1645422622.png

 
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Experienced people say that soapy water will cause rusting issues, and recommend proper leak detection fluid that won't do that. I bought a bottle but haven't had to use it yet.

The easiest places to start checking are probably the atmosphere holes for the two regs, the grub screw plugging the supply hole for angled manometer bracket, and the foster fitting (check valve not working). Atmosphere hole on first reg is on the bottle adapter, and for the second reg, its the hole on right side of gun where the angled manometer bracket would go. Grub screw sealing angled manometer bracket supply hole is next to the atmosphere hole. I haven't done it, but you may be able to put some tape over those spots and see if it gets pushed off.

*Note about that grub screw sealing - Factory method I believe is to attempt seal without anything else and if that fails, put a small piece of cut oring in the bottom of the hole and reinstall the grub screw. On my M3 I had something crazy happen where the oring chunk got sucked into passageway downstream of second reg and cause slow plenum refresh.

I feel where you are at right now with not wanting to ship it, and also not wanting to be without it. If I was in your shoes, I'd pickup leak detection fluid and see if I could figure out where the leak is, then watch some videos on getting to that part of the gun. Most of the leak spots are pretty easy to get at and work on, even the regs. If the leak is in the valve/plenum area, that requires near complete disassembly of the gun. If your leak is in a spot you think you can handle, FX will send you the parts for free. They will also pay to have it shipped back if that is the route you want to take. They may even be OK with you trying and sending it to them in the event you do not succeed - just ask them first.
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TDK thanks for the input. Checked it this morning was down 40 bar from fill after cooling off and setting for 24 hours. So filled it up and wanted to shoot while I had a day off. Got her tuned in with 80 shoots averaging 886 fps with a ES of 16, with 1 low of 877fps assuming it was due to the tank and reg 1 matching at 150 bar, if removing that 877 shot the ES would have been 11 so happy with that and a STD Dev of 2.2. At 50 yards from the garage with about 5 feet of snow she is shooting hole in hole so happy with that. 
TDK I checked everything you mentioned so decided to check again looking for the leak. I used dawn and water before hate doing that so picked up some leak detector. Went over every place with no luck. After shooting topped of the gun then realized I didn’t recheck the foster fitting. And that is where the leak is. It’s small but there. Pulled the foster fitting out and was a little gummy where the check valve sets. Cleaned it up and tried it again and still leaking. I did put some silicone grease very little where the believe it is derlin seals inside the foster fitting so may remove it again, wipe of all grease and try it again. 
Thank you TDK so frustrating looking for a small leak that I over looked the foster fitting. 
 
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The o-rings sealing fill probes and foster fitting areas get "burned" or "burnished" from the rushing high pressure air and become glazed and brittle. Also, the metal valve assembly holding the o-ring may also have seated itself crooked at one time and slightly scratched the sealing surface as well. To fix either condition, disassemble and polish the metal parts and install a new o-ring. Remove all the sharp edges of the o-ring grooves with fine wet-dry sandpaper so it does not cut the o-ring either.
 
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Thank you TDK so frustrating looking for a small leak that I over looked the foster fitting.
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I don't know what it is, but there is a tendency to focus on the most complicated and unlikely areas when troubleshooting, and I think it gets worse the more technical you are. I do it all the time....blow right past the simple/easy explanations and go right to the weird/rare stuff.

You should email [email protected] with a copy of your receipt and tell them you've got a foster fitting check valve leak you can't stop and that you are requesting new parts. They'll send them for free.

Polishing to stop leaks is the real deal. Worked like a charm on my reg using the 3M polishing cloth Earnest uses. I'd still start with the new parts, though, as its an easier fix for you and this doesn't seem like a part that typically needs a polishing to perform as intended.
 
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Thank you TDK so frustrating looking for a small leak that I over looked the foster fitting.
Click to expand...



I don't know what it is, but there is a tendency to focus on the most complicated and unlikely areas when troubleshooting, and I think it gets worse the more technical you are. I do it all the time....blow right past the simple/easy explanations and go right to the weird/rare stuff.

You should email [email protected] with a copy of your receipt and tell them you've got a foster fitting check valve leak you can't stop and that you are requesting new parts. They'll send them for free.

Polishing to stop leaks is the real deal. Worked like a charm on my reg using the 3M polishing cloth Earnest uses. I'd still start with the new parts, though, as its an easier fix for you and this doesn't seem like a part that typically needs a polishing to perform as intended.
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TDK

Yeah never even thought of looking at the fill port. I did email them on Monday haven’t heard nothing back will have to call tomorrow just to get the ball rolling. I removed the male fitting and cleaned it up. Didn’t see any obvious nicks or anything so put it back together and still leaks. Can still shoot just will lose air over time. Don’t want to mess with it anymore until I get an o-ring kit as the port o-ring is pretty rough looking so at least can shoot until FX sends a new port or my o-ring kit gets here. 
 
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Here are a few places where you may find a leak on your Impact. O-rings are the Achilles Heel of all pcp airguns - so my advise is for you to go the the parts drawing for your rifle - (https://fxairguns.com/wp-content/uploads/2021/04/F10370-Impact-M3-1.pdf) and make a list of all o-ring sizes and order some of each from Oringsandmore. You can call FXUSA and ask them to email you a complete list of the o-ring sizes for your rifle, and if you like you can also purchase an o-ring kit from them with all the sizes for your rifle. This way whenever an o-ring does fail you can fix it yourself. Don't know how to take your rifle apart and put it back together? These videos from Airbuks will teach you how to do that. Good luck finding your leak...

All the best, Chuck

https://www.youtube.com/watch?v=rxBexX6sjuQ&t=1s / https://www.youtube.com/watch?v=EoEDWxy0zAE&t=1s

https://www.oringsandmore.com/metric-70-orings

https://www.youtube.com/watch?v=HK8S8dAAKrI

https://www.youtube.com/watch?v=XnZtNYUbiDo

https://www.youtube.com/watch?v=-HmVepkBuNo

https://www.youtube.com/watch?v=-SXSflA30k4

https://www.youtube.com/watch?v=MKQyoYg8-JY

https://www.youtube.com/watch?v=FshNkfwBmxc
 
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No there is nothing under that screw...there is no place for an o-ring like there is under an air gauge. So if you have an air leak from there you just need to de-gas your gun, coat the threads of that little screw with a generous amount of Blue Medium Strength Loctite, then screw it all the way in until its tight and let it sit over night without any air in the rifle to push out the Loctite, then air up your rifle the next day and check to make sure you cured the leak by applying a drop of soapy water on it...if there are no bubbles you are good to go...if there are bubbles repeat the above steps.
Best regards, Chuck
 
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srkhan, I'm guessing you completely overlooked the text above the video links?
"...there is nothing under that screw...there is no place for an o-ring like there is under an air gauge. So if you have an air leak from there you just need to de-gas your gun, coat the threads of that little screw with a generous amount of Blue Medium Strength Loctite, then screw it all the way in until its tight and let it sit over night without any air in the rifle to push out the Loctite, then air up your rifle the next day and check to make sure you cured the leak by applying a drop of soapy water on it...if there are no bubbles you are good to go...if there are bubbles repeat the above steps."
Best regards, Chuck
 
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