What is an acceptable Air Leak-down on a PCP

[Pellet]

My new XF Bobcat very slowly leaks down its air pressure - by about 100 psi in 2 or 3 days. Is this normal - would you think it's acceptable?  I've never had a PCP air gun with a gauge before and perhaps they all do this but I never had the means to see it happen and question it.

[Nomadic Pirate]

An accetable leak ?.......is NO leak

[pyroboy33]

Absolutely not, none of my PCP's from the $200 Discovery to the $1000 S510 have ever leaked one bit. For a $2000 gun that is unacceptable, I would highly recommend you send it back for repair. This is like the 4th or 5th post about a leaking bobcat I have read this month not to mention off center gauges, leaking regs, and ill fitting stocks.....FX needs to step up their game really quick if they want to continue to compete for a spot in the Bullpup marketplace  .   

[wwonka]

None of my PCPs leak, at all. And I keep 3/4 of them charged for months on end sometimes.

[Mod90]

It's not supposed to do that Pellet. My advice is send it back & let them either fix or replace the defective unit asap.
You've spent a lot of money for a top of the line gun, you shouldn't have to deal with bottom of the barrel problems so soon after acquisition.

[Nomadic Pirate]

It's not supposed to do that Pellet. My advice is send it back & let them either fix or replace the defective unit asap.
You've spent a lot of money for a top of the line gun, you shouldn't have to deal with bottom of the barrel problems so soon after acquisition.

x 2

[Bullfrog]

Absolutely what others have said. It shouldn't leak at all ever.

[Norm_m]

X2 to that

[bthrel]

I've got 2 PCP;s, zero leakage … I'd insist it gets repaired as well

[starlingassassin]

if its only 100psi i would have to ask if its being stored in a cooler place than where you last looked at the gauge.


as the pressure will drop in cooler temps and rise in warmer temps.



just a thought.

[Ribbonstone]

Yes, PCPs are not suppose to leak at all.  However, anyone who hasn't had one ever leak should add the word "yet" as ALL OF THEM will sooner or later leak.  Just not in the cards for o-rings to last forever and ever PCP ever made will sooner or later leak. The goal is to make them leak free, but somethings you have to delay the goal.

Kind of up to you how much you can stand.  It's hard to trace down a really slow leak (if it leaks from 3K to 0 in 4 months, thats something like 1 psi per hour).

Will try for leakless.  But if I have one that barely leaks (like the above example), will live with it until the leak gets large enough to identify the two major leak soursed (valve stem vs tube o-rings).

[grobe1458]

the only acceptable leak (if you want to call it that) is when you pull the trigger.
over time they will, even some new ones will such as my bsa but once i tore it down and cleaned it, it's about as air tight as a ducks behind.

[Ribbonstone]

So far.

Don't expect it to last forever, 'cause it won't.  That's why the seals are replaceable in the first place.

Have had PCP's hold air for 10 years, but know that 10 years of living in a high presssure/high oxygen enviroment is going to kill the o-rings eventually.  All i'll usually do it wait until the leak is detectable between the two major sources (valve stem and tube o-rings).  If it's the valve stem, will end up replacing the valve stem AND all the tube's o-rings (figuring they're all the same age and all suspect). If it proves to be an o-ring in the tube, will still replace all of the tube's o-rings, but won't replace the valve stem.

[Pellet]

Thanks to all, I'll recharge it one more time to get an accurate rate of leakage so I can describe it more objectively then try to return it under warranty.

[Ribbonstone]

Point I was trying to make (and not doing a good job of) was this:

They are not suppose to leak.

They all sooner or later will leak.

When they do, identify what’s leaking and fix it.

For your 100psi, that could be a temperature change.  All PCP's warm up from air compression when they are filled (the faster you fill, the warmer they get).  Warm air will read higher pressure than cold.  Common to fill at gun to 3000 and come back 1/2 hour later to see 2900 on the gauge (or even 2800).

Exernal temp will alos drop air pressure. Filled at 75F then stored where it's 62F, you might see 100psi drop.

[jeff76]

if it dropped 100psi and that's all, it could simply be a temp change thing.  if it drops 100 and then another hundred and then another its definitely leaking

[Pellet]

Thanks everyone for your insights.  I'll charge it again to take more accurate readings of the pressure drop over time, then call the dealer with specifics and hope for a warranty repair.

[Pellet]

I contacted AoA and they immediately issued a return label and authorization, no hassle.  They found the leak, fixed it, pressurized it and watched it over a 6 day period to be sure they fixed the only leak.  I have that puppy back in my hands now and it's still holding the pressure they filled it to.  So, I'm a happy camper.  Ideally it would have never leaked but AoA stood by their product and made it right under the warranty, that's all one can ask.

Thanks everyone for encouraging me to contact the seller.  I'm very please with the seller's response.

[Mod90]

Glad to hear the issue was resolved with minimal hassle. Now go enjoy shootin' that thing. And don't forget, pics are always welcome.

[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?