Monday, December 21, 2009

Daisy 717 Repair Part 2

Before I get too far ahead, I installed the new foam wiper seal and the o-ring piston seal. Got 'em from Daisy a few weeks ago for a dollar.

One whole dollar nets you two o-rings and a foam ring of the correct size. I bought 3 kits just for the novelty of having spares.

Screwed the piston head back onto the body and reinstalled it into the compression tube.

Coated all the mating surfaces with moly...

and bolted it back together.

Back to the valve. Popped off the snap ring

The exploded valve. Original seals are on top. Replacements scavenged from various o-ring kits are below. The o-ring on the left for the body of the valve is a #012 And the small stem seal is a #005.

Reassembled.

Put it all back together and it still leaked. Super. Just for kicks, I then installed the new style valve. As I expected, it leaked.

The pump assembly does not need to be disassembled to get the valve out of the 7XX guns. Just the three phillips head screws on the left side of the shroud need to be removed. Pull the grip frame off and it all comes apart. I can get the valve out now in under 60 seconds--blindfolded. Then I took the valve apart. Again.

Sure, no problem I'll just clean up the valve stem seal on the lathe.

Matched the angle and literally just dusted the surface with the cut.

Reassembled. With teflon tape this time, too--just for good measure. Yep. Leaked. Not to be outdone, I'll just add an o-ring to seal the valve...

Cut the stem seal down to fit a R-01 o-ring.

And gorilla glued it in place.

Like so. Reinstalled--Reassembled--Leaked. It slowly occurred to me that it maybe wasn't leaking from the valve after all. I held the barrel assembly in the compression tube with a tight fitting drift and cocked the gun. It held. Moved the drift slightly and it leaked. The o-ring on the face of the valve is allowing blow-by.

Removed the ring. Looks fine--actually it is fine. It's brand new from the one buck Daisy seal kit. Then I saw the problem.

If you look carefully at the round hole in the casting you'll notice that it's not actually round. It's oval shaped and allows the valve to sit too far back in the compression tube. Only talking about a couple hundredths here, but it's enough to allow air to leak past the o-ring very slowly. Sounds like it's coming out through the transfer port. But, no, it's leaking from just in front of the transfer port. Thought about shimming it, then just called it quits and called Daisy customer service. A new barrel/valve body assembly cost $17 bucks. Sold! Good news is that the new body will work correctly with the extra valve I have. And, yes, I ordered another check valve as a spare. Will it work? What else could go wrong? This is why I don't work on airguns for a living... Well, it's one reason....

Initially, I thought the gun had somehow been over-pressurized--maybe someone attempted multiple pump strokes to get more power. But Nick hit it on the head. A previous owner over-adjusted the piston stroke and it levered the valve backwards on the closing stroke. Yeah, I need a new part.

Note to 7XX owners: The lever should close with just a bit of resistance. The parts are soft. Be careful.

5 comments:

Bobby Nations said...

Derrick,

Good catch! I am going through the same back and forth with a 30 year old Daisy 880. It has the exact same valve, and I'm seeing the exact same results. A very slow leak. I'll take another look and see if anything is out of round. Back in my younger days, I absolutely, positively overpumped this gun, so stretched pin holes are a definite possibility.

derrick38 said...

Bobby,

I cut some thin sheet metal strips, curved them to fit and put them in the forward half of the locating holes. They effectively fill the ovalized portion of the hole. The gun still leaks down--albeit much more slowly. I want a more permanent fix for this one--hence the new barrel/valve

Claudio said...

Thank you! I am going through the same thing. I am going to take it appart for the first time and check. My Gun is a Daisy 747, and am assuming its the same. How do I order parts to canada from daisy?

Email me if you can Zore @ Shaw.ca

cheers

Claude

Claudio said...

Thanks for the info on this, I am going through the same thing ( slow leak sounds like its coming from the transfer port).

I am going to take it appart for the first time I am assuming the 747 is the same internaly.

I have been beating my head against the wall on this one.

How do i get parts in Canada from daisy ?

Cheers,

Claudio

Felice Luftschein said...

Claudio,
Not sure, best thing is to call Daisy and ask them how to order parts, they have pretty good email support.

The 717 and the 747 are pretty much the same but I think the 747 has a slightly different trigger mechanism.