Gauntlet finally leaks air

[Dbez1]

After about one year and 6,000 jsb’s, it’s developed a slow leak. The simple solution is to send it back to Umerex and have them deal with it under warranty. Two problems with that is turnover time and 2) the darn thing shoots so well, I don’t want to take a chance they’d screw it up. Is anyone aware of a Hojimoto (or someone else) video on uTube dealing with o-ring replacement?  PA is now selling Gauntlet o-ring rebuild kits so there must be a demand. Is there a first place to look for the problem?  I’m not experienced at tinkering with PCP’s but do have a friend who’s a gunsmith and we’re not afraid to try with a little guidance. Thanks.

[Wayne52]

I don't have the Gauntlet but I've sealed up pcps and it's relatively easy IMO however I always have been mechanically inclined so I'm sure any knowledgeable gun smith should have no problem.  I don't know if there's a good exploded view of the Gauntlet but that would be a big plus for anyone working on one.  Along with Haj's instructional video's it shouldn't be a problem.

[Dbez1]

I found the following exploded view in one of Hajimoto’s videos. Not the best copy but better than nothing.  Many thanks to Haj!

[Tucobenedicto]

The problem is to determine where the leak is,bottle-regulator or rifle?
A first step can be to test the bottle and regulator out of the rifle with soapy water,on the fill nipple,gauge,regulator body.
If the bottle is ok inspect the rifle.

[Kerndtc]

It's rather simple.

Process of elimination first, degass the gun with included tool.

Remove the bottle and inspect the two orings that seal on the top of the threads on the regulator.

If those look good, then your leak is in the gun. If you are lucky it will be one of the 1/16CS 3/4" OD orings on the bottle block there it slips into the air tube.

There are only five orings and a poppet seal.

Two orings on the bottle adapter, two orings on the regulator, one O-ring on the valve body and the soft plastic poppet seal. 

How long does it take for it to leak out?

[nervoustrigger]

I like Cameron’s approach of start by isolating the bottle from the rifle.  On several occasions I’ve had a slow leak crop up on one of the tapered threads (e.g. gauge or Foster) or one of the burst disks.  Seldom anywhere else.  But just to put it into perspective, there are at least 9 places the bottle can potentially leak:
 
1.       Gauge threads
2.       Gauge itself
3.       Burst disk 1
4.       Burst disk 2
5.       Foster check valve
6.       Foster threads
7.       Regulator body (where it meets the bottle)
8.       Bottom end of regulator spool
9.       Top end of regulator spool
 
But don’t let that long list bog you down.  The point here is just that there is a lot of opportunity for a leak so that’s why checking the bottle makes a good first step.  Just remove the bottle and pressurize it to at least the regulator’s setpoint, fill a clear drinking glass with water, dunk the regulator in and watch for bubbles to form.  For a really slow leak,  it may take a few seconds for a small bubble to form.  This will find leaks that would otherwise be missed by spritzing soapy water and looking for bubbles.
 
When done, just shake it off and let it dry.  Maybe blow it off with compressed air if you have it.
 
The only leak you could see that may not be immediately obvious is if one of the O-rings on the regulator spool is leaking.  In that case you’d get bubbles forming at the seam at the bottom of the bonnet.  For what it’s worth, I’ve yet to experience a leak from there.

[Dbez1]

Thanks to all for taking the time to help me. I’ll get on it early next week.
PS  It takes 2-3 days to lose 1,000 psi. But it used to hold air forever.

[falvesjr]

Here's a PDF schematic for the Gauntlet...

[Dbez1]

Thanks Fernando.