First inside cylinder on Benjamin pump

Sun Optics USA is the place to call.

However you may want to consider just getting one of the $40 Chinese pumps from Amazon, Walmart, or Aliexpress. I wouldn’t be surprised if the replacement part were about the same price. I have a couple of the cheap pumps and they work as well as the Benjamin and even seem to be more reliable.

Okay, that’s good news that it’s not cost prohibitive to repair it. 



Regarding adding a desiccant filter on a pump whose inlet is via the handles, what I did on mine was push a piece of vinyl tubing through the opening in the end of one of the rubber grips and feed that down to a canister filled with desiccant beads. And I just plugged the hole on the opposite grip to ensure the pump gets only the dried air.



I admit that a canister isn’t as convenient as having one of the little inline filters affixed straight to the base, but the larger volume does a much better job at removing moisture. The air doesn’t remain in contact with the desiccant for very long so the idea is to maximize the volume of beads and the distance the air has to travel to make it all the way through. That has worked well for me here in the humid southeast.

I admit that a canister isn’t as convenient as having one of the little inline filters affixed straight to the base, but the larger volume does a much better job at removing moisture. The air doesn’t remain in contact with the desiccant for very long so the idea is to maximize the volume of beads and the distance the air has to travel to make it all the way through. That has worked well for me here in the humid southeast.

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This advice is spot on especially for one who uses the pump in a humid environment. I constructed a similar system for a Hill MK3 -- https://www.airgunnation.com/topic/who-uses-a-pre-compressor-filter-desiccant-when-direct-filling-a-gun/#post-429106

I imagine the concept is the same and constructing it in a way to hermetically seal the tubing when not in use ensures dry air into the system.

Back when it failed, I did buy one of the cheaper chinese models, certainly not cheap like today pumps, but cheaper than the Benjamin. I would still like to get this one working so I can install inline input side desiccant system. I would have to find the part for less or not exceeding the price of one of the new chinese pumps.

I can add desiccant filter on the intake of the Benjamin, and all the chinese pumps I have seen have the intake in the handle where it is not accessible to even modify to accept desiccant filter.

Cylinder is 18 bucks and change sourced from where Sun Optics sends one to for parts to fix that pump.

Yahoo, I am going to be flush in pumps now.

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Hi Ridin Lou, I've got a benjamin too same problem as you found on the outer low pressure tube. If you don't mind I could sure use the info on a source for parts on the pump. I tried to call sunoptics usa but could not get any info from them. Apparently Duane who used to be so helpful has passed and the pump business has been sent on to his family but they would not give me any contact information. But they would certainly like to sell me a desiccant filter that they still have in stock for the benji pump LOL

RidinLou, shoot me a pm, I’m pretty sure I have a couple of spares out in the shop.