mod 312 Benjamin Franklin

[ironworkerwill]

Does any know if the pre '95 repair kit sold by Pyramid Air will fix the release port valve on these rifles. To my knowledge Crossman will not fix these rifles but rather give a very modest trade in value on a newer model. After owning the newer model I said "NO THANKS".

The actual problem is: Will not hold compression. I figure that it is the release port as I hear gas escaping from the barrel. If it where the check valve I'd assume the gasses would escape from the pump body.

Any suggestions?

 

[Deltaboy1984]

Oil it good.

 

[ironworkerwill]

Ok...

 

[Grayrock]

I have one too and it just lost compression a couple of years ago after decades of service. Where would one introduce the oil?

 

[Grayrock]

Oops- just remembered- mine is a Model 310, not 312

 

[ironworkerwill]

310 and the 312 should be very similar. This one belongs to my father in law, and being a former maintenance worker, he oiled it PLENTY. The oil hole is just below the pump cylinder opening on this 312.

The kit has valves and a valve removal tool. I've ordered it because, from what I've seen, the tool is necessary so if the valves fit its a bonus. I should have the repair kit today.

 

[ironworkerwill]

All the valves in the kit worked! The pump seal did not, it needed modification. There was no hole in the center to attach it to the pump rod. The new rubber seal was completely different than that of the 312. After drilling the center out with a 5/32" drill bit, it works as good as new.. Or according to what I hear.

Other modifications needed where; turning down the spring boss on the release valve to fit inside the valve spring. And shortening the pump push rod.

There is a strip- disassembly video on YouTube that was very helpful. Without that video i wouldn't have been able to disassemble the rifle.

 

[rodinal220]

Great airgun site,this may help future repairs on these. The owner has articles on repairing both the 310 and 312.Use the search function on the site.

http://anotherairgunblog.blogspot.com/

 

[ironworkerwill]

Thanks rodinal

 

[ironworkerwill]

These are the old check valve disk, check valve spring, and pumper seal. Notice the pump seal has a hole in the center. The new one did not.