Daisy 747 Pesky Intermittent Leak

[Ronno6]

My first 747 reseal.
Not going as planned.....

There was an audible air leak heard from the breech when the gun was cocked and pimped.

First attempt, the exhaust valve seemed to me a touch loose in the valve body.
Could it be that simple?
Nope.....
First time....total silence........no leak.
Second try............leak.
So.........
I replaced the exhaust valve with a NEW one.
First cycle...........NO leak,
Ahhhhhhhhhh
Second cycle.........LEAK.
Grrrrrrrrrr

Tried another new valve, and the same old leak....

So, I replaced the O-ring valve body to pump tube.
NO LEAK !! Or, so it seemed.
Never heard a hiss......

But, I had not replaced the piston O-ring, and I wanted t be thorough.
Re-assembled, and..............LEAK !!!

What else is there to try???

[Ronno6]

The leak has to be getting past the exhaust valve poppet.

Would it help if I was to lap the valve stem to the valve seat by disassembling the valve and chucking the stem (thru the hex body but without the spring) shaft up in my Dremel... Then installing the assembly in the valve body and lapping using a polishing compound or toothpaste???
VERY GENTLE pressure to avoid too much heat...........

Hmmmmmmmmmmmmm

[Back_Roads]

 Worth a shot, make sure no burrs in that area that may chew up the poppet.

[Ronno6]

Worth a shot, make sure no burrs in that area that may chew up the poppet.

I gotta whole bag of poppets.......

[threesuns]

Ron, I had a 717 with a similar issue and lapped the valve. It didn’t hurt but did not completely fix either. I’d read NOT to store the 7x7’s under pressure but I did it anyways to help the new poppet conform to the seat and that is what worked for me.

[Ronno6]

I lapped the stem to the body ant is is repeatedly holding air!
Fingers crossed..........

[Duckfish]

http://www.pilkguns.com/tenp/spd747.htm

This might help.

Maybe not.

[eeler1]

I don't think the Daisy 7x7 series pistols were supposed to hold air indefinitely.  Single stroke target guns are really intended to pump and fire shortly thereafter.  If it still fires after an hour or so, consider it good.  Now, hearing air escape from the barrel while pumping, that's another thing.  I know this is an old thread, but that's my $0.02

[Methuselah]

https://anotherairgunblog.blogspot.com/2009/12/daisy-717-repair-part-3-final.html?m=1