Crosman 140 Multiple Teardown Issue

[Methuselah]

I did a search on this gate for pin press, got 2 pages, 58 posts, 2 interesting but none a related solution.

As titled, I acquired a model 140 that didn't build pressure.

There's a knerreled pin through the hammer that must be removed to push out the valve. I've done this twice, first time hammer and punch, second (because I mixed up the springs) punched out again but pressed back with heavy c-clamp.

It builds pressure but leaks, so now I'm afraid more teardown cycles will destroy the receiver. Since the pin is threaded on both ends perhaps the rifle would hold together anyway, but of course it's best to avoid finding out.

I'm trying to figure out what the best practice method would be to get this pin out and back in again with minimal damages. Second insertion was difficult even with light oil...

So far I'm looking at a harbor freight 1 ton arbor press, a hand held chain link breaker/press tool, a rigged up ball joint separator tool, and suspect there are other options?

I have bought a bunch of vintage airguns recently, mostly to work on for something to do, and find there's a really good chance this one could end up a favorite, so I don't want to blow it, even if I  have to admit defeat and send it out for repair!

Please suggest best practice and appropriate tool(s)?

[JPSAXNC]

 To remove and install the plug, I thread a screw about half way into the hole and then tap on the screw to push out the pin. If you look at the bottom of the plug you will see the knurl marks on the plug. To reinstall the pin  I line up the knurl on the pin with the knurl marks on the plug and then tap the pin in. HTH

[Methuselah]

Thanks for the reply James.

If I understand you correctly, there's also knerreling in that rear plug? If so, I wasn't aware.

Now you got me thinking about removal too. I didn't have issues until the 2nd reassembly, it simply didn't want to go in far enough until I forced it with a heavy c-clamp.

So I need to try and match the knerreling to marks on both receiver and rear plug? If so, it may be quite buggered up. That pin has screws in both sides, perhaps it isn't urgent it "engages" the receiver solidly? (Just thinking out loud)

[JPSAXNC]

Uh O, It only goes in one way as I recall, I haven't worked on one in years, but the knurled end of the pin should be toward the bottom. Push it out from the top and put it back in from the bottom. Another thing about the leak, it might not be anything you did. Pumpers condense water, the water collects on the o-ring that seals the valve and corrodes the steel the o-ring seals against. I have a 140 and a 1400 that are unrepairable.

[Methuselah]

Uh O, It only goes in one way as I recall, I haven't worked on one in years, but the knurled end of the pin should be toward the bottom. Push it out from the top and put it back in from the bottom.

Does the splined part of that pin bind that rear plug?

Another thing about the leak, it might not be anything you did. Pumpers condense water, the water collects on the o-ring that seals the valve and corrodes the steel the o-ring seals against. I have a 140 and a 1400 that are unrepairable.

Were you able to see the bad spots without a borescope?

I appreciate your insights James. I've got an arbor press on the way to deal with the pins and since dissassembly is easier I suppose I'll know what I'm up against before it arrives.

It occurred to me it can be assembled and tested without the barrel and rear plug - at least it seems worth a try...

[Methuselah]

This may have wound up at least partially in multiple threads, sorry ... rear plug is drilled through in one operation, same diameter both top and bottom.

I cannot say if one should stop driving the knerreled pin when it meets the plug, bc (obviously) I already hit it. But at least I put the plug back same orientation.

Front pin got difficult on insertion. Maybe orientation matters or helps? Since it's probably being removed at least one more time, I'll take a closer look. Reason in another thread (So it's old)...

I've got a chain breaker tool on order and may try it instead of the arbor press.