Friday, November 19, 2010

Crosman Model 99, Driving Me Nuts, Part 1

The title says it all. I started by trying to tighten up the pellet feed mechanism, successfully. I stole the cam ring from the beater model 600 pistol.11191016

The ring binds on the cam rod.

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I had to do a little operating on the ring.

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Just some work on the corners and chamfering the edges. Red line shows how much metal is contacting the cam rod.

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Still locks up on the cam rod.

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More polishing of the corners of the cam rod and now it feeds fine, very little play.

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The slow leak was bothering me though. Removed the exhaust seal. It was the opposite of pliable.

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Making a new seal.

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Cut off. Then installed. But it was still leaking.

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The seal where the valve stem passes through the body was troubling me. I took apart a Crosman model 38 valve to see if I was missing something. That washer…I didn’t notice it in the 99 valve.

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Found it.

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Down in the valve was a rubber seal and a plastic sleeve.

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On later model 38’s they use an o-ring but the original seal (center) looks like a flat ring. Skipping ahead, I think this might be one of the reasons I ‘m having a leak. I’ll be making a flat ring seal later to test this theory out.

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The washer, new o-ring and plastic sleeve.

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The valve stem is the same as the model 38 valve stem.

After taking it apart several times, making another seal, wasting about 4 CO2 cartridges, still not finding the leak (if anything the leak was getting worse), I decided to build a test unit.

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Empty (!!!) CO2 cartridge tapped for an air fitting. Only about 2 threads holding it in, so I didn’t hook it up to my big compressor, just the little paint compressor.

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The compressor. At least I won’t be wasting 40 cents every time I test the valve. Unless of course it leaks at low pressure and seals at higher pressures, in which case I’m screwed.

In any case, I’m going to take a break from this rifle for a little while as I have an even more complex project that I want to get to next week.

2 comments:

Was a kid with a pellet rifle said...

You took a little break and it's been more than a year! :-) Did you quit or just not posted the continuation?

I was looking at this because I have a Model 99 in a closet here. I haven't looked at it in decades and wondered if it would work. I presumed the rubber ring/seal around the piercing pin would be stiff and brittle and need some kind of replacement, but it seems there's other stuff that may need replacing too. I wouldn't get in to this as seriously as you do, and you have the know how, the tools and materials I don't. :-)

But thanks for the info and documenting the job, it's appreciated.

Good luck,
Ivan

Nick Carter said...

Ivan,
I just got tired of it as I wasn't having much luck getting it running right. I'll probably pick it up again now that I have more time this winter.