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PostPosted: Wed Mar 08, 2006 8:46 am 
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Joined: Sat Mar 04, 2006 2:43 am
Posts: 2879
Location: Pickering, Ont.
I've seen them mentioned in a few old posts.

I seem to have a major seal failure in my Mark I. Haven't used it for years, and vaguely recall that was why after testing yesterday. But now I can get the info to fix it I hope. I will try to figure out which "end" is the major leak point, but I think a complete re-seal makes sense even if I can pinpoint the prob.

I will try to do it myself, but if I can't maybe I'll ship a bag of parts to somebody and have them do it... I think I have enough airguns that I should probably learn to do a few things myself. I have owned Crosman airguns for more than 35 years (still have 'em) and have NEVER taken one apart even a tiny bit. This is weird, as I'm into electronics and take EVERYTHING I buy apart, just with mech things I'm worried about little parts springing out...


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PostPosted: Wed Mar 08, 2006 8:50 am 
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Joined: Thu Sep 01, 2005 11:41 am
Posts: 6063
The gunis easy to take apart...about 25 parts or so. Be sure to locate the schematic and service manuals for it here on the CAF.

I, too, would like to buy a seal kit. I stripped one down last night to fix a leak and investigate a lack of power.


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PostPosted: Wed Mar 08, 2006 10:37 am 
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Joined: Sat Mar 04, 2006 2:43 am
Posts: 2879
Location: Pickering, Ont.
Yup, I have all the manuals.

Further "analysis": I put 1972 vintage Pellgunoil (not red, used to get some oil in the box when you bought Crosmans up until the 90's)) in the Mark I, much more than usual but not a whole lot, and positioned the gun upside down and let the oil flow inwards overnight. Today I filled the kitchen sink with water (bubble test) and put in a new CO2 cart. Pierced it, no gas escaping from the barrel or the part where you load the cart (only dipped them slightly in water). But, when I flip the piercing lever, that's when the gas escapes, only when the lever is not in the normal position. Otherwise, no leaks visible. I did a foolish thing: pointed the gun at the sink full of water (but not in it) and fired. Water all over the place, we can call that Craig's power test...


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PostPosted: Wed Mar 08, 2006 11:18 pm 
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Joined: Sat Sep 03, 2005 9:25 am
Posts: 3587
Location: Ontario, Canada
Roger at AirgunsCanada often has Mark1 parts in stock. At one time he was selling package deals with a valve+stem+and all seals. Maybe give him a phone call 1-780-554-4867 (evenings). Roger lives in Alberta and does the shop at home, in the evenings. Leave a message if he doesn't answer, or try another time.

Many Mark1 seals can be bought at local stores. They are all standard sizes, not metric. Nitrile works but you could upgrade to a better material if desired. Hydraulic shops often have o-ring seals. Look in your yellow pages for seal and gasket dealers or hydrualic shops. A typical nitrile o-ring is about 50 cents each.

The Mark 1 bolt seal can be replaced with a nitrile oring because it doesn't take extended pressure. I have used the common 1/4"ODx1/8"IDx1/16"thick oring.

The valve body can use a common 5/8"x1/2"x1/16" oring. It's a trapped seal and has nowhere to expand. Many seal&gasket dealers will have harder material than nitrile but the softer nitrile will work in a fix... until better seals can be found. I have used nitrile with good results.

The small seal inside the piercer cap is the same size as the bolt seal and it should be harder than nitrile but I have used nitrile without problems. This is a trapped seal and has nowhere to expand if it gets bloated. The nitrile seal worked for me for a long while and cost was 25 cents.

The outer seal on the peircer cap should be hard material like urethane. A soft nitrile seal will bloat and tear.

Todd


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 Post subject: Crosman seal kits
PostPosted: Thu Mar 09, 2006 9:56 am 
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Joined: Fri Dec 09, 2005 5:21 pm
Posts: 71
Location: Sidney, Nebraska, US
Bryan and Associates sells seal kits for Crosman guns at reasonable prices. I deal with him often. He is in Anderson, S.Carolina. email him at (bryanandac@aol.com) or phone at 864-261-6810.
I have a Crosman MK II with custom 14 inch Walther barrel which is one of my favorite pistols

Tell him the Nebraska Airgun Addict sent you.
Doug Law
dlaw1940@yahoo.com


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 Post subject:
PostPosted: Thu Mar 09, 2006 3:24 pm 
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Joined: Sat Mar 04, 2006 2:43 am
Posts: 2879
Location: Pickering, Ont.
Thanks guys.

It appears to be the small inside piercer seal. I happen to have a whole bunch of those small nitrile ones that I use for another hobby. All I gotta do is figure how to get it out...

I will mention that the CT 's around here have many sizes of nitrile O-rings in the area where they keep by-the-piece small hardware, where I usually get mine. The 1/4" ones mentioned are the smallest size they carry, $0.20

Anyway, I left the gun with the CO2 cart in overnight, then took it to the 10m range position in my basement. Hit the bullseye and the rebound hit me in the nuts. Too bad I only had eye protection on. At 10m on lowest power. I guess it's holding gas well enough... Not bad for original 1972 seals. And the sights held since I haven't used this gun since '91 when I got the 1322. By the rebound on low power you can see why I changed to a pump for indoors.


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 Post subject:
PostPosted: Sun Mar 12, 2006 2:43 pm 
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Joined: Sat Mar 04, 2006 2:43 am
Posts: 2879
Location: Pickering, Ont.
FWIW, after a bit of use that seal in the piercer seemed to heal itself, doesn't leak at all now even though I tried to make it...that Pellgunoil is kinda magic. Holds gas better now than it did last I used it, remember I used to get pissed off because gas would leak out in a couple days, pretty much had to use a cart all at once. Guess I didn't oil much when I was a kid, probably why I have so much vintage oil left...

I made a new trap using junk I found in my basement, inspiration from the trap threads...no rebounds now, plus the lead is collected too (I also melt it down for reuse).


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