Problem with benjamin 392

[Tradarcher]

I have a 392 that is only about 2 months old and it is not dumping all the air.  It will continue to build pressure when I pump but will only let out some air. It just started doing this any ideas on a fix?

[BenjiHunter]

Has it been lubed?
All three pivot points every 50 shots works for me.

[GumpIsrael]

How many pumps before it stops dumping all the air? I had this problem and it turned out to be a faulty exhaust valve. Ordered rebuild kit from pyramydair.Com and got it taken care of. Also a good time to do some mods while the valve is out. That being said I would only disassemble the gun if it shoots like a laser, because those are getting harder and harder to find. However if the gun doesn't shoot very straight, I would say send it back to crosman.

[Tradarcher]

Well it's not consistent some shots will dump all the air others will not.

[GumpIsrael]

It's more than likely that the exhaust valve is bad. However my thoughts also lean towards the spring behind the hammer as being weak. Either way it's pretty easy to disassemble the gun and change everything out. There is a good video by a guy on youtube called Notsodumb, I think this is the url: 

[Old Corps]

Thanks for that link!

Ed

[redlined_b16a]

As asked before
How many pumps  does it completely dump?
If you are dumping atleast 7-8 pumps the g7n is probly shooting withing factory specs.
If its dumping less than that Od say you have a weak hammer spring.

A very easy fix is installing a few small washers behind the spring to make it tighter.If you put to many spacers the bolt wont be able to cock the gun.

Another solution is go to a hardeare store and buy a larger diameter spring.I use a .043 wire (may be too strong for a stock valve)and I compressed the old spring and measured it.
Compressed the new spring and cut it about 1/8" longer.

Install and if bolt wont cock it trim a 16th at a time until it fits.
You may need a .035 spring though.My gun has alotof valve and linkage work and will dump 14 manly pumps.

I find that 10 pumps is about the useable max pumps the factory linkage can handle,plus its a big power upgrade.

[Tradarcher]

Yea it only dumps about 5 pumps completely.  I'm under warranty so I'm sending it back.

[GumpIsrael]

I second redline's idea about it, and if your still under warranty  sending it back is a good way to fix the problem! 

[Rivers3Plinker]

I keep debating getting one of these things and working it over like my other pumpers but so many issues reported by so many members with them. I just don't know. I was also considering getting one straight from Tim at MAC1 with his roid magic done to it first.

[anuthabubba]

I was also considering getting one straight from Tim at MAC1 with his roid magic done to it first.

Don't think he sells them that way anymore. Suggests you buy one, shoot it some to confirm its accuracy/function, then send it in for the Steroid treatment.

[GumpIsrael]

Steve, I agree with yrok. I went through 3 or for to get the one I have now. It shOT like a laser until a fall mess up the rear sights. Just find one that shoots straight and gets good groups and send it to tim.

[Rivers3Plinker]

Steve, I agree with yrok. I went through 3 or for to get the one I have now. It shOT like a laser until a fall mess up the rear sights. Just find one that shoots straight and gets good groups and send it to tim.

Thanks I get it now. Makes sense that Tim has better things to do than order, test, return, test, return, test, return, and finally get a good one. I was under the impression he was correcting whatever was wrong with them if any problems before juicing them but sounds like that's not feasible.

[n4spd]

My first 392 bought this year started to retain air after 1-2 months.  Initially it dumped all 8 pumps but then only dumped 6 pumps.
The wood stock was also poorly made so I sent it back rather than tweaking it.

Got another one, the wood stock was better and it dumps 8 pumps.  1-2 months later, it only dumps 7 pumps.  I'm just thinking the hammer spring is weak or gets weak.  I just dry fire it after each shot (in order to get consistent fps for each shot).

The quality control on the newer 392 is just poor.  Buy it from Amazon because they have a great return policy.