My tuned and modded QB79 gave up on me :(

[FRANK]

well my my QB79 quite on me the vavle will not let co2 go out.

I see the firering pin move and hit the vavle but nothing happends I did many test and it seems like its the vavle.

now I need to know how ezzy is it to fix. and I will need a seal kit to do this?

I will fix this QB79 since It was shooting quater size grooping at like 40 yards and I was still setting the scope,
this QB shoots at 766fps on co2 and the grouping was awsome.

I been having lots of trouble with this thing but I dont know why I love it.
probably because I love underdogs that come out winning. but it's losing now.

it's been un reliable. /SAD

[rsterne]

It may be that the filter and/or screen in the valve have disintegrated and plugged the valve.... It may be quite difficult to bleed down the pressure, but critical you do so before disassembly....

Before you take it apart, you will have to make sure it's not under pressure.... then remove the tank.... After you remove the tank block from the end of the tube, you will notice a large slot on the end of the valve.... loosen that one turn and then after removing the valve screws you can slide the valve out the front of the tube....

When you replace the valve, don't tighten the two halves fully, install it, and then tighten the front half to put pressure on the seal....

Bob

[FRANK]

took the tank off but I'm sure there is still co2 in it?
could my vavle be hydro locked? I just had this tuned/modded, and only shout about 300 pellets with it.

ok I will make sure there is no more presur and take the vavle out.

[rsterne]

If you removed the tank (and assuming you don't have a valve between it and the gun) there can't be any CO2 left in the tube, unless the hole in the tank block is plugged and I have no idea how that could happen.... I suppose if both ends of the valve were plugged there could still be CO2 in the valve, but again, very unlikely....

If you find it difficult to remove the screws holding the tank block to the tube then that could be an indication there is pressure trying to push on the tank block.... If they spin out easily, and once they are loose slightly you can move (wiggle) the tank block easily it should be safe to disassemble....

Bob

[AirGunEric]

Check that the adapter the tank attaches to still has the detent pin in place to allow the tank valve to open. If you had no Co2 pressure when disassembling- where did it go if you didn't shoot the pressure out?

[SeanMP]

Check that the adapter the tank attaches to still has the detent pin in place to allow the tank valve to open. If you had no Co2 pressure when disassembling- where did it go if you didn't shoot the pressure out?

I agree by the description the tank valve isn't opening.

[FRANK]

there was pressure, well co2 coming out every time I unscrew the tank.
I will need to take the vavle apart.

[FRANK]

well today I took it apart 2 more time and I will tell you this, the 9th time is the charm. I got it to work perfect.

I will be ordering a few oring kits, and a few goodies too.

Im a very happy guy today got my QB working but don't ask me what was wrong with it since I don't know.
all I know is the valve was not opening. and now it is.

[poil27]

prety weird , but glad it works now i'm verry happy for you !

[rsterne]

Just had a thought.... The steel block that mounts behind the valve.... can it be put in either way?.... and if you put it in backwards, does it prevent the hammer from striking the valve stem?.... It's been a while since I had a QB apart and I can't remember if that could happen.... If so, it could explain the problem (maybe).... Sean?.... Anyone?....

Bob