Working on a Benji

[shadow]

Blue Streak, older model. Question fella's before I pull her apart, what's the pump piston seal material made of. I'm thinking rubber etc. but want to get the skinny on it before I pull her apart. She pump's but wont hold pressure which tell's me that the seal is bad I'm thinking. So what do we have fella's, thank's .  Ed

[shadow]

Ok I couldn't wait lol, I pulled her apart here's what I got. Piston/shaft and cap on the end. Now there's a O- ring but it was just sitting in front of the piston, does this fit over it and into the grooved area on the piston. Thank's, Ed

[moe1942]

If it pumps up but won't hold pressure it is probably the check valve. I have the same problem with a 392. The fix from Crosman is not expensive.

[shadow]

Nope it wont pump up, no resistance when pumping, does the O-ring go onto the piston, thank's . Ed

[fatback]

Ed the rubber pump seal is working fine if she pumps up. here is an online diagram to a sheridan rebuild. http://www.network54.com/Forum/275684/message/1177168737/sheridan+C9+rebuild in figure 5 you see all the internal parts disassembled. the valves and lead washers need to be replaced. there is a guy on gunbroker who sells the kits. it comes with new pump seal lead washers new valves and tools to do the job. here is a link to his auction. http://www.gunbroker.com/Auction/ViewItem.asp?Item=99625226
I just rebuilt a 1969 sheridan rocker safety blue streak with this kit and it worked flawlessly.
hope this helps,
Chris

[shadow]

Thank's Chris, that helps is it possable to just replace the rubber O-ring and does that seat into the grooved area on the piston?.thank's, Ed

[fatback]

Ed, I didn't have that o ring in mine and if you look at the diagram I don't see that o ring on there either. not sure how old your rifle is but it wasn't on mine. a 1969 model blue streak. I replaced the pump seal 1st and she pumped up but just leaked out the barrel. then i bought the kit and repaced all the valves and seals and she shot good as new and is still holding fine. I store the gun with 1 pump in it.
Chris

[shadow]

I'm working on it for a friend and when I pulled her apart the piston and shaft came out with the O-ring just sitting on the end. I'm wondering if the O-ring seat's at the base of the tube and the black hard plastic end on the piston is just wore down and not creating pressure. Ed

[fatback]

not sure on the O-ring but the piston head ( plunger) should be pliable not hard. it is made of rubber. when I took the piston seal/ plunger off of mine it was very hard and brittle. I had to use a dremel to cut it in half and get it off. the new 1 was soft rubber and popped right on into the groove.
Chris

[fatback]

if the rubber plunger is brittle then the other rubber internal seals are probably dry and brittle to and need to be replaced. the kit I gave you the link to has all the parts and tools to do the job.
Chris

[shadow]

Thank's again and that's the problem it is hard and brittle, need's a new one for sure. Thank's a bunch for the replies guy's.:) Ed

[shadow]

The seal is in a bad way and I popped it out of the piston. Ed

[shadow]

Got the link, thank's. Ed

[shadow]

Just looking to replace the rubber pistion seal, all other seals are good. Can I just get the seal and where, thank's. Ed

[Splash]

Here you go Ed, this should work.
http://jgairguns.biz/catalog/product_info.php?cPath=78_566_85&products_id=8802
Mike