Reconstructing a Crosman 2100C Valve

Posted by on December 28, 2013

Crosman 2100 goes “boom”

Ever heard of “dieseling” … Me neither, until the valve blew up on me. So now what?, order a reproduction off of eBay and wait a month to get it? — End up paying more for less? … Or turn a new part out of 6061 Aluminum?

Getting the metal turnin’…

Started off with 1″ 6061 rod, I didn’t have anything closer to 3/4″ so a lot of it went to waste… All operations were performed by hand, no power feeding was used in this case.


Once the blank was turned down to size I had the option to leave the top flat for a flat cup or turn it down to a taper, like the original. I ended up turning a taper on it right after I installed it onto the body (which I then held on the chuck to perform the last operation on the valve cover)

Next time I’ll leave it flat and replace the cup with a straight one as well. Plus the flat top allows you to drill indents for tooling (installing / removal of the valve cap) whereas with the tapered cap you have no means to grip it without causing some form of damage…

The threads are 1.25mm, rather interesting finding a non imperial thread on what I would like to think is an American product. Needless to say every other part of the valve assembly was fine, except for the plastic inlet seal valve (I belive it to be PTFE, but I used Delrin/Acetal which is what I had in hand to turn a new one).

The o-ring groove was cut with a parting blade, my o-ring profiled carbide tool needed to be resharpened so I took a shortcut, the 90° edges were smoothed down with a green brillopad before installing the o-ring.

Sorry, no pictures of the finished part (I wasn’t thinking about documenting the process) But here’s the finished reconstructed valve:


New o-rings, new transfer seal. Yep I ported it while I was at it.

It’s important to clean the parts after turning them, I use ph-neutral soap and hot water. Whenever nitrile or silicone o-rings are involved, I don’t want any pretroleum based oils anywhere near them!

For lubrication always use SILICONE BASED LUBRICANTS, stay away from any other type of oil when it comes to the air path or any parts involving rubber o-rings.

Remember kids: Dieseling is bad for your toys!

Stay tuned as I convert a 1077 into bulk-fill using my own pressure tank design!

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