Air Venturi Will not hold pressure

The first thing is finding the leak. Don't use soapy water. It will rust your gun. I made that mistake with some of my pcp lol. Use some leak detector that doesn't cause rust. Spray where you think it can be leaking from until you find it. We can't help you by just asking where the leak is, cause we don't have your gun. It could be leaking from anywhere. Some place to look for, the gauge, transferport, barrel, reg. Fill port.

Balloon over fill port and barrel work well to test those areas.

Soapy water is fine, just tear down and dry everything out once you find the leak...rust won't occur in the short span of time this takes unless you leave it unattended afterwards...So don't use the soapy water unless you're fixing the leak then and there.

-Matt

Stubbers said:

Soapy water is fine, just tear down and dry everything out once you find the leak...rust won't occur in the short span of time this takes unless you leave it unattended afterwards...So don't use the soapy water unless you're fixing the leak then and there.

-Matt

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I second Matt's direction. I use a water based leak detector then dry the gun with compressed air.

Firewalker said:

I second Matt's direction. I use a water based leak detector then dry the gun with compressed air.

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I pop my pieces in the oven at 170F, get my gun baked, she likes it.

-Matt

I'm completely new to PCP and after a lot of research, felty comfortable that many folks were getting very tight groups out of the Avenge-X so I purchased an Avenge-X Classic (poly) stock in the 25 cal bottle version - The first few outings went fine - then it wouldn't hold air above about the regulator pressure. It had arrived with about 1700 PSI in it so it felt like I must have done something wrong.

I found that the fill fitting was about an 1/8 turn shy of tight -
The fitting between the fill and the bottle was slightly shy of tight
The Burst Disk fitting was slightly shy of tight
One of the two white o-rings on the bottle on the gun side was split about half way around - replaced and lubed with Silicone.

It still leaked intermittently - including dropping to zero overnight one night.

I don't have expertise in this mind you but I'm trying -

Then I realized that it leaks every time I leave the gun un-cocked for storage and it holds pressure when it is cocked - just my two bits but it seems to be working on my gun.

My working tune (from the web) has the hammer at "5 turns plus two bumps" and the regulator at 170 bar -

M Volle said:

Then I realized that it leaks every time I leave the gun un-cocked for storage and it holds pressure when it is cocked - just my two bits but it seems to be working on my gun.

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Too much pre-load from hammer spring on the valve stem. and an absence of Hammer free flight / gap.

Solutions:

1) Reduce HST (hammer preload)
2) Add .04"-.05" free flight / gap (requires knowledge)

-Matt

Have you checked the fill check valve to see if there is a slight leak?

I have checked the fill port with a balloon - it was a very slow leak that resolved with a touch of silicone on the o-rings in the fill fitting.

Matt - It would seem to impact my tuning to back off the spring every session but it also seems like leaving it cocked all the time is likely to cause drift in the tune as well -

How complicated is it to add a little space?
I understand the idea and think that sounds like the "correct" solution - hammer not on valve when at rest.

I'm fairly handy with mechanical things and machine tools - is it an adjustment or actually a modification/addition of a spacer or shim?

Thanks

Home Dopey and Lowes both sell the leak detector liquid. One bottle goes a long way if diluted a lot. I clean my muzzleloaders with water. HOT water. The heat drives off the last of the moisture. And hot cleans better too. Getting guns wet...not an issue. Leaving guns wet....ISSUE.

I don't know if your found your leak yet? But I've been finding a common leak that sounds like it's a valve leak but is in fact an external leak from the receiver block.

The pin is called an axle on the schematic drawing. If you remove this part from the airgun and it's easy to pull away, the orings are junk. They've been dry rotting. It's an easy fix but a frustrating one to find if you don't know about these orings.