Canadian Airgun Forum

I filled the air tube last night with 2000 lbs air pressure for a hunt the next morning, (approx 12 hours). When I got up the gauge showed a drop of approx 200-300 lbs of pressure. Has anyone else had this experience and how can I fix it?

its normal for PCPguns to leak if theyre not properly sealed. take everything that might leak totally apart, check every o-ring, and replace any that doesnt look good. de-burr everything that might cause damage to o-rings when you reassemble the gun. check the valve, and the valve-seal. lube everything with silicone-grease, as normal lubes might cause explosions when put under pressure.

should be okay if you manage to put it together without ruining the seals, and apply some silicone-grease to the seals.

If you pumped it from empty to 2000 psi without allowing it to cool every 500 psi or so you could simply have experienced a pressure loss from the temperature change when the air you heated up during pumping cooled.... especially if you pumped it quite vigourously.... or filled it from a tank.... I notice that even when just topping up from 1000 psi to 2000 if you leave it sit for an hour or so, it will lose about 100 psi from cooling.... but that's it.... My Disco might lose 100 psi over 2-4 weeks of storage once the temperature is stabilized....

If the gun continues to lose pressure after it has returned to ambient temperature, then you may need to strip it apart.... The most likely culprit is the O-rings on the outside of the valve or the rear one on the guage block as they are easily damaged when you slide them past the guage hole in the tube.... you MUST deburr this hole the first time you have the gun apart or it will shred O-rings very easily.... at least mine did.... Don't even THINK about trying to pull the valve out the back, you will destroy the O-rings on the many holes and slots.... it has to go out through the front.... MAKE SURE THE GUN IS COMPLETELY EMPTY OF AIR BEFORE DOING ANY DISASSEMBLY.... If you have a de-gassing tool, use that.... otherwise shoot it down to ZERO....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

Thanx a lot! That's the culprit. I've been watching the pressure now for eight hours since I refilled it and it hasn't moved off of the 2000 psi mark @ stable room temp. It was pretty chilly out this morning which would account for the pressure loss.

I'm waking up a sleeping thread... and this is my first post so I don't want to just ask and not share results. This thread Googled for .. well, the thread title so I find it appropriate.

My Discovery was stored for a bit (year+) and it may have been under a little pressure (not sure). When I charge it, it leaks majorly AT the bolt. It is actually blowing out the "L" slot for the bolt. I lubed the o-ring on the front of the bolt (would be the firing pin on a firearm) where it goes into the breech but this did not help.

I took the stock off and suspect that there is a valve under the pellet chamber that is leaking. ?? There are a zillion screws and fittings so I don't want to go too far without input.

Thanks in advance!

(The only language selection was "British English" so I hope that you can read this without "u's" in various places. )

The valve is leaking.... It probably has a bit of dirt under the valve head preventing it from sealing on the seat.... It's basically the last thing to remove after you disassemble the entire gun.... so if you're not handy, its a PITA job....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

Thanks Bob! So assuming I am handy (depends on the day WHEN I drop a screw and lose it), are you referring to the breech gasket under the barrel or the valve assembly in the muzzle? I have a parts diagram and it would look more like the former consider it would be the hardest to get to.

The parts diagram I have is: http://www.crosman.com/pdf/manuals/BP1K ... %20EVP.pdf

Best regards,

Brett

If you have a continuous leak it can only be the valve poppet (ie #18H).... If it only leaks when you fire it, then it is the breech seal (#24)...

Note that the valve (#18) is located directly under the breech seal (#24) which seals against the top of the valve.... On that diagram it just shows that it goes into the main tube FROM the muzzle end....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

sounds to me that the valve body oring is leaking.
if the valve stem is bad it will leak out the barrel

Walter....

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Walter

Oh joy! Ugh.. I'll post back when it works.

Thanks again and I will report on the results.

Best.

True, if the bolt is closed.... If it still leaks out around the bolt T-slot with the bolt closed then you are correct, Walter.... the O-rings that are supposed to seal the valve in the tube (# 18D) are not doing so.... The air is leaking past the outside of the valve and out through the cocking slot in the breech and tube....

Either way, you need to pull the valve.... which means pretty much taking the entire gun apart....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!