PCP Air rifle leak diagnosis help please

tuck1

Well-Known Member
Morning folks

Im after some advice on behalf of a friend please. Due to family circumstances he is very financially constrained at the moment so the usual advice of "send it to a gunsmith " can't apply in this case unfortunately.

He has a Falcon Praire Lighthunter with a slow overnight air leak. It appeared to be coming from around the front end of the cylinder (charging port, pressure gauge) area, and he has renewed the gauge. No joy.

My question really is (I know nothing about PCP's) how do people go about diagnosing these leaks? Water bath? I've heard of balloons taped over muzzles and cylinders which he has done, but it's a slow leak and would that just indicate a leak somewhere inside which happens to be exiting at the muzzle/cylinder?

Are these things very complex or dangerous to work on? Aside from the pressure, could a chap with a decent tool set and time on his hands strip one down and have a poke around, or will it be full of highly sensitive valves and widgets which implode when touched by a human?

All advice gratefully received, as I have none to give him...

many thanks
 

ciscokid

Well-Known Member
First off if he does not feel confident working on air guns he should not, they are pressurised to 200 bar which is approx 3000 psi , very hazardous. However a simple test is to put a balloon over the cylinder end and then over the muzzle end. If the cylinder end inflates slowly overnight then it is probably the filling valve or o ring. If the muzzle inflates the balloon then its a leak around the firing pressure release mechanism. Either way take it to someone who knows what they are doing and tell them of the balloon test results , this will save them some time and him money. Remember Compressed air is dangerous!
 

Highlandsjohn

Well-Known Member
Morning folks

Im after some advice on behalf of a friend please. Due to family circumstances he is very financially constrained at the moment so the usual advice of "send it to a gunsmith " can't apply in this case unfortunately.

He has a Falcon Praire Lighthunter with a slow overnight air leak. It appeared to be coming from around the front end of the cylinder (charging port, pressure gauge) area, and he has renewed the gauge. No joy.

My question really is (I know nothing about PCP's) how do people go about diagnosing these leaks? Water bath? I've heard of balloons taped over muzzles and cylinders which he has done, but it's a slow leak and would that just indicate a leak somewhere inside which happens to be exiting at the muzzle/cylinder?

Are these things very complex or dangerous to work on? Aside from the pressure, could a chap with a decent tool set and time on his hands strip one down and have a poke around, or will it be full of highly sensitive valves and widgets which implode when touched by a human?

All advice gratefully received, as I have none to give him...

many thanks

If you discharge the pcp it will come apart in the reverse order it was assembled,If he has the skill.john[h=3]owners manual falcon prairie - Pyramyd Air[/h]
 

Edinburgh Rifles

Well-Known Member
the falcon is one of the easiest PCPs to strips

diagnosis is no different to an inner tube
soapy water from a spray gun save submersing

empty it completely by cocking and firing until it no longer emits air from the muzzle

be careful not to mark the brass fitting when unscrewing
PTFE tape is a simple fix to a gas leaking cylinder

while you are in there de-twang it with a 12 bore plastic was drilled through the middle (falcon detwanger - Google Search)
 

enfieldspares

Well-Known Member
ER! You've made my Sunday! I clicked on the link about de-twanger modifications just for interest (I've regulated Scorpion T-10 that was regulated by Ratworks but knowledge of other brand PCPs is always useful) and eventually came to this. From a "Sid" on Airguns BBS. I've cut an pasted it:

Couldn't Falcon solve this problem by not fitting the twanger in the first place ?
biggrin.png
biggrin.png
biggrin.png


On a more serious note, just what is this obsession with silencers ( which a de-twanger must come under the heading of ) on airguns ?

If you were having a meal in McDonalds and your mate suddenly fell backwards off his chair with his brains sprayed out all over the floor, kicked a few times and then lay still what would you do ?
Think " Well, there's something you don't see every day" and carry on munching your burger, totally unfazed because you didn't hear a bang or the famous Falcon twang ?

I know that rabbits aren't as bright as most of us ( I reckon they are brighter than about 75% of airgunners, which isn't saying a lot) , but they do tend to notice their nearest and dearest flipping into the air and landing belly fur up, devoid of life. Makes them nervous and prone to run away for some strange reason.
The noise of a pellet impacting the skull is very clearly audible on it's own, although I often wonder how many contributors to the BBS have actually heard this noise for themselves

Which leads me to question the value of sound moderators on airguns....as long as it's taking the very noticeable "crack" of a PCP away then I think that's enough myself. Twangs don't even enter into it.
Moderators on springers are a waste of effort IMO, due to their much softer muzzle report.

Maybe de-twanging gets you better HFT scores or something

I do know that if I was going to spend £15 on my Falcon then I would paint it NATO green to cover up all that horrible shiney blueing and wood and take the £12.50 change to the pub
 

Ranger22

Well-Known Member
On my T10 the fill port comes out very easily once the air is released. If the Falcon has a similar set up there will be two O rings needing replaced. I would guess there will be a guide on the tube on how to do it. I wouldn’t advise using tape to seal the leak.
 

Edinburgh Rifles

Well-Known Member
ER! You've made my Sunday! I clicked on the link about de-twanger modifications just for interest (I've regulated Scorpion T-10 that was regulated by Ratworks but knowledge of other brand PCPs is always useful) and eventually came to this. From a "Sid" on Airguns BBS. I've cut an pasted it:


Ah AirgunBBS...
Home of the introverted.....

I personally spent the princely sum of feck all detwanging my FN12
made a significant difference to the noise which I am confident does allow me two magpies in the hand as opposed to





On my T10 the fill port comes out very easily once the air is released. If the Falcon has a similar set up there will be two O rings needing replaced. I would guess there will be a guide on the tube on how to do it. I wouldn’t advise using tape to seal the leak.


much more likely to be leaking between the main tube and the end cap on the Falcon
 

tuck1

Well-Known Member
Thanks all. I'll point him towards this thread and we will have a look into it when time allows.
 

sauer

Well-Known Member
I de-twanged my Hassan at-10 with a small brush designed for scrubbing interior of bottles ... watched it on YouTube & works a treat

Completely different on firing no twang !


If paul
 

Cyres

Well-Known Member
In my case with a Daystate and a AA S200 just immerse end in water bath and soon locates leak. Odds on it will be an o ring which has gone. Easy to replace once air is released. Use high pressure vacuum grease on o ring when reassembling. In my case i had a tiny leak on the male quick fill probe, sometimes a tiny bit of dust will cause minute leak. If you tap it with an engineers hammer it will depress the ball bearing enough to expel a tiny amount of compressed air and often will reseat the bearing and leak seals. Also if you have Dowty washers then must be replaced. Wrekin pneumatics sell packs of 10 on line.

I expect there will be lots of vids on line of how to strip the weapon.

D
 

tuck1

Well-Known Member
Thanks again, some very informative stuff there.

Silly question time. My friend informs me that last time he dunked it, air was bubbling out from the fill gauge. This has subsequently been replaced. I take it no air should be able to exit the gauge? Would it be safest to submerge it without the gauge attached or would that defeat the object?
 

Cyres

Well-Known Member
Dont know but if its got a dowty washer and its not been replaced I bet that will be the issue.

D
 
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