What is an acceptable Air Leak-down on a PCP

[Back_Roads]

 If hand pumping and you decide the gun is too low to shoot without having to top it off when you want to go shoot.
Or the leak is causing other issues.
 A compressor owner can put it off till it does not hold air long enough to shoot a fills worth of pellets. If I notice 1000 psi or more loss in a week it gets new seals.

[Ribbonstone]

All PCP’s will eventually leak. Some can go years all buttoned up and not leaking, but sooner or later they will leak (I always think “yet” when folks say their PCP “has never leaked”). 

It’s like saying the tires on my care never wear out, the oil never needs changing, or the battery never fails to crank it...the o-rings in a PCP aren’t forever.  You can hear the “yet” in your head.

Certainly don’t expect any of those things to happen to a new car...and you’d be right to expect a new PCP to not leak.

Good idea would be to change ALL the seals at once...if one leaked, and they were all put in at the same time in production, would be better off with all new.

REALLY slow leaks, like the 100-200PSi over a week or two and can’t be blamed on temperature change, are the hardest to find/fix. 

Air gunsmith or DIY...would really need to keep gassed up for awhile to be sure you fixed it...and being lazy, I’d NOT put it all back together until I knew for sure.


New gun….ship it back and forth and hope it’s fixed...repeat as many times as it takes to end up fixed.

Old out of warranty rifle...ship it to someone who will fix it for a fee….repeat shipping as many times as needed to get it fixed.

DIY..which can be a learning eperience...but can void the warranty (if there is one).

[JimD]

I bought a good sized assortment of O rings because I am sure I will need to replace some.  But when I carefully tracked the leakage of my 25 caliber Avenger for about a week and found it was leaking 150-200 psi/day I called and got a return number and sent it in.  It didn't start doing this after holding air for awhile, it leaked slightly from day one.  Air Venturi has been very polite but my two requests for an update on the status did not get me any information.  But it's only been a couple weeks. 

I bought my Benjamins Marauder Pistol first and it does not leak at all.  I doubt it will always do that but I think it should at least as long as the warranty period.  I feel the Avenger should do the same.  Neither are expensive guns but they still should work as intended.  Or the manufacturer should fix them. 

After the warranty runs out, I accept that fixing them is on me and I will do it.  But I feel like it should at least start out working. 

[Nomadic Pirate]

Sorry for bringing this post up but I'm also looking for a final answer about it. As we know, nothing is totaly leak free. What in this case would be acceptable not justifying the tear down? I mean, 100 psi/week? month? year?

Well, that is not quite correct.

yes probably at some point all PCPs will develop leak but normally they should not leak at all,

I have 7-8 years old PCPs that never leaked yet,....one 6 years old one started leaking out the fill port last week so I changed the check valve and was back to no leak in 15 minutes total

[csitas]

I tend to agree with the Ribs here. Some times fixing just one thing ,---can open a new can of worms. Been there , done that , and over time have seen that.Age can be a factor.

[Firewalker]

I guess that as long as I can find it and fix it, I'm good with it.

I've repacked hydraulic cylinders on heavy equipment, repaired jets on a boat, I can pick a few o-rings....

[null]

All guns break. They are mechanical.

O-rings are considered wear items in my books...

[EricFR]

Sorry for bringing this post up but I'm also looking for a final answer about it. As we know, nothing is totaly leak free. What in this case would be acceptable not justifying the tear down? I mean, 100 psi/week? month? year?

Well, that is not quite correct.

yes probably at some point all PCPs will develop leak but normally they should not leak at all,

I have 7-8 years old PCPs that never leaked yet,....one 6 years old one started leaking out the fill port last week so I changed the check valve and was back to no leak in 15 minutes total

Maybe I should be clearer. When I say that nothing is totally leak free I mean that there are always losses, as little as they are (even not measurable), some molecules or so every seconds or minutes which in turn would turn out to be 10 psi after a month or even a year. You never can have the perfect sealing as there are ever some irregularities in surfaces (even when polished to mirror) and the rubber can also be a little porous. Nothing is perfect.

The question was about what was the tolerable amount of leak. 

Now I have some answers, it seems that up to 100 psi in a month is still OK.

[Nomadic Pirate]

Sorry for bringing this post up but I'm also looking for a final answer about it. As we know, nothing is totaly leak free. What in this case would be acceptable not justifying the tear down? I mean, 100 psi/week? month? year?

Well, that is not quite correct.

yes probably at some point all PCPs will develop leak but normally they should not leak at all,

I have 7-8 years old PCPs that never leaked yet,....one 6 years old one started leaking out the fill port last week so I changed the check valve and was back to no leak in 15 minutes total

Maybe I should be clearer. When I say that nothing is totally leak free I mean that there are always losses, as little as they are (even not measurable), some molecules or so every seconds or minutes which in turn would turn out to be 10 psi after a month or even a year. You never can have the perfect sealing as there are ever some irregularities in surfaces (even when polished to mirror) and the rubber can also be a little porous. Nothing is perfect.

The question was about what was the tolerable amount of leak. 

Now I have some answers, it seems that up to 100 psi in a month is still OK.

I would never be OK with 100 psi per months leak, I have multiple guns that have been sitting for several months and they are exactly at 100 BAR where I left them, .......I don't find any leak acceptable I'm afraid.