Discovery poppet failure

[AmBraCol]

Had air leaking from the barrel so tore down the Discovery.  Attached is the condition the poppet was in.  Never saw such a thing before.  Can't imagine what would cause it to disintegrate that way.  All I use on the inside is pure diver's silicone grease.  Anyway, when I dug into my box of goodies to pick out a new poppet, found out that I've got four 1377/1322 poppets, and no spare Discovery poppets.  Oops!  Well, I DO have spare Discovery valves so stole a poppet from one of the spare valves.  In the meantime, I'm wondering if a 1377 poppet could be used in the Discovery, or if it won't seal properly.  The smaller diameter would promote better flow, wouldn't it?  If it'd seal up in the first place, that is.

[rsterne]

1377 poppet has a 1/8" shaft, like the MRod poppet.... the one in the Disco is 5/32".... However, you can bush the valve housing in a Disco down to accept an MRod poppet, so likely a 1377 one could be made to work also....

I'm wondering if that poppet had a tiny amount of air trapped inside and/or developed a crack.... when the cavity filled with HPA it exploded on firing....

Bob

[pecor]

I did what Bob suggested with an Mrod poppet , Completely Happy with the results even on a stock .177 valve, Thanks Bob . Those disco poppets are junk in my mind, And had the same results as you experienced. I saved his post on this,     Here is a copy and paste of Bobs Mod------  Installing an MRod poppet is not that difficult.... The stem is only 1/8" instead of 5/32", so you have to bush the stem hole in the valve down for the smaller size.... You can get brass tubing at Hobby Shops, made by K&S, that is 1/8" ID x 5/32" OD.... A short piece of that, glued into the back of the Disco valve, is all that is required to enable you to use an MRod poppet.... The OD of the MRod poppet head is smaller, allowing more flow past it inside the valve

[mann]

I have also done the mrod poppet mod in my disco valve makes for alot of improvement on my bottle regulated disco

[AmBraCol]

1377 poppet has a 1/8" shaft, like the MRod poppet.... the one in the Disco is 5/32".... However, you can bush the valve housing in a Disco down to accept an MRod poppet, so likely a 1377 one could be made to work also....

I'm wondering if that poppet had a tiny amount of air trapped inside and/or developed a crack.... when the cavity filled with HPA it exploded on firing....

Bob

I don't have a dedicated shop area so getting to tools is a matter of shifting things around - and didn't take the time to dig down to the calipers.  Why bother when one can use trial and error to waste time instead?        My brain is like a steel trap (rusted closed at times) so decided to modify a 2240 poppet instead of using the one scavenged from the spare valve.  Used the angle grinder with cutoff wheel to remove the CO2 puncture piece off the end of the poppet, chucked it into the hand drill and rounded and polished up the end.  Assembled everything (at least I didn't attach the receiver, barrel and stock) and found out that the 2240 poppet won't seal the Discovery valve.     

OK.  Disassemble everything again, replace the 2240 valve poppet with the one from the spare valve, reassemble and voilá! It holds air!!!  Note to self:  put in a reserve supply of poppets - including both Marauder and Discovery. 

Bob, I don't think that's the case.  The plastic or whatever they use is brittle and disintegrating.  It's like some plastics that get left in the sun and the UV rays do their thing on them.  Or perhaps exposed to some kind of solvent.  But what?  I bought this rifle used a couple years ago and replaced both the intake valve and the firing valve with brand new parts straight from Crosman's parts department.  And I've only used diver's silicone for installation purposes.  Now I'm curious about the poppets people make from other materials.  How's it done?  This one has the valve stem head in the middle of the plastic part and I don't see how that could be done on a lathe, it looks like it's injection molded there.

In the meantime, she's back together, got a better scope mounted and just waiting for a chance to get to the range and try her out.

[AmBraCol]

I did what Bob suggested with an Mrod poppet , Completely Happy with the results even on a stock .177 valve, Thanks Bob . Those disco poppets are junk in my mind, And had the same results as you experienced. I saved his post on this,     Here is a copy and paste of Bobs Mod------  Installing an MRod poppet is not that difficult.... The stem is only 1/8" instead of 5/32", so you have to bush the stem hole in the valve down for the smaller size.... You can get brass tubing at Hobby Shops, made by K&S, that is 1/8" ID x 5/32" OD.... A short piece of that, glued into the back of the Disco valve, is all that is required to enable you to use an MRod poppet.... The OD of the MRod poppet head is smaller, allowing more flow past it inside the valve

Thanks Jay and Mark for the idea.  Now to find where my brass stock is and see if I've got a piece available that'd work.  Like mentioned above, didn't dig down to the calipers so ended up doing a trial and error with the 2240 poppet, still not sure why it didn't seal, need to dig out the calipers and do some measuring.  It'd be nice to have a dedicated shop area with a place to set my tools up properly.