IZH-46M Leak at Breach

[dsm90awd]

I've 6 months and maybe 1000 rounds thru my IZZY but have recently been experiencing intermittant velosity dropoffs due to a leak at the breach. With the breach open and the compression cylinder charged it holds air fine. Once I close and lock the breech, I hear a whisper comming from under the breach.

I've read the piston seals need lubrication and have been pretty methodical about it, using a light Lucas brand air-tool oil. Definitely has enough oil in it.

Any suggestions?

Thanks!

[Fred Mannis]

I've 6 months and maybe 1000 rounds thru my IZZY but have recently been experiencing intermittant velosity dropoffs due to a leak at the breach. With the breach open and the compression cylinder charged it holds air fine. Once I close and lock the breech, I hear a whisper comming from under the breach.

I've read the piston seals need lubrication and have been pretty methodical about it, using a light Lucas brand air-tool oil. Definitely has enough oil in it.

Any suggestions?

Thanks!

With only ~1000 rounds through the pistol, you should be ready for your first (perhaps second) lubrication of the piston seal. Don't know anything about Lucas oil. I have used Beeman Ultralube or Crossman PellGunOil to lube the seal

[dsm90awd]

With only ~1000 rounds through the pistol, you should be ready for your first (perhaps second) lubrication of the piston seal

Thanks for the reply. Would the piston seal's performance have relation to whether the breech was locked down or not? I ask as with the breech in the locked up position, it holds air, but a soon as I close it, is when it starts to leak.

[william]

This is a real puzzler since simply closing the breech should have absolutely no effect on anything. Is it possible that it leaks air slowly when the breech is open and that closing the breech makes it audible by forcing it through a smaller aperture?

Let me suggest you operate the main lever and wait awhile; then close the action, shoot it and see if it has lost significant pressure. My Izh held pressure for well over an hour; maybe 3-4 hours is a good test.

If you're inclined to lube the piston seal I suggest a very thin coat of high-vacuum silicone grease. It's totally nonreactive and stays where you put it. It's not a good metal to metal lubricant, so use it only on soft parts.

[dsm90awd]

I put a short video of what I'm talking about on YouTube (first time at this so isn't real nice).

http://www.youtube.com/watch?v=dY3NUvLPFWo

I did listen/feel on and around the breach, and was no air escaping. Can see from the vid that once the breech is closed, it's obviously leaking.

Regarding lubrication, I've just been adding a couple drops at the piston and working it in every 200 or so shots. I've not taken it apart at all.

[Fred Mannis]

I'm out of ideas. Suggest you talk to Buck Parson - the Pilkington gunsmith - and ask him. You may have to send it to a gunsmith for repair.

[dsm90awd]

I went ahead and disassembled the innards of the compression chamber and re-lubed with some synthetic grease. Was optimistic when my first 15rounds were at full pressure, then the now familiar leak resurected itself. Doing some research, the valve itself has been know to crud up easily, especially with the gunk grease the Russians use. Plan is to try to remove as much as I can manually, but wonder what can use to get the remainder out without harming any rubber seals. Would WD40 be to caustic?

[Fred Mannis]

Since you have the gun apart, why not just replace the seal? This will let you thoroughly clean out the old grease and clean the valve and start over with fresh seals. See http://www.pilkguns.com/tenp/izh46slideshow.exe for the procedure

[dsm90awd]

I think the problem was related to lubrication as I cleaned out all the oem goo in the back half and re-lubed with some synthetic (along with working some into the valve seat) and the leak is gone. Nice to see all the online diagrams/how-to's to disassemble, unfortunate that I needed them so soon.