That's a beauty!Good job on the reseal.
Yes, that is the cap that I was talking about. Here is where I got my O-ring info: I had to pry out the old seal (not really an O-ring with a small screwdriver. Then I greased up the 4mm x 2mm O-ring and kinda twisted it into place. I was pretty amazed when it fixed my leak!
Check out this link: http://anotherairgunblog.blogspot.com/search/label/crosman%20140 The one I had in my previous reply had a period at the end which didn't work. I got the O-rings mentioned in the above link at my local true-value hardware store. They were either 69 or 79 cents apiece. You can also buy "kits" on ebay that have all 4 o-rings for about $10.00 I think.You have a Crosman 99? So do I. It's probably my favorite vintage Crosman airgun.
Hey sandpiper,I have taken my 99 apart, but not the valve. Can you tell if part -53 is screwed into the valve body? I have read that sometimes heating the valve body will help when removing stuck parts. You could also start a post on this forum, since I'm sure someone probably had the same problem. Erik
The metal washer is what seals the o-ring into the valve cap. I assume it is "press fit" into the top of the valve cap. I think you might have to bite the bullet and buy a new valve cap.
An Oring will work in the Cap for a while but the proper seal is a Quad seal. Same sizing as an oring so the number will be the same as the oring you got. I like to use Buna 90 for the 011 and Viton Brown for the 111. I have a new Flat top piston head that rebuilds the factory piston so it can use a replaceable 90 Durometer 111 Urethane oring.http://www.mac1airgunshop.com/flat-head-piston-for-early-crosmans-p/flhepi140.htm
When I resealed my 140 valved 2nd variant 760 I used a regular oring in the valve cap, still going strong several years later. I did get some quad seals for eventual replacement, but still shooting fine with the plain oring. I did not remove the retainer, I just snuck the new seal in past the retainer. These older 760's are great!