Hand Pump Died



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Offline Pellet Fun

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Hand Pump Died
« on: February 18, 2019, 03:03:08 PM »
I recently bought one of the affordable Chinese hand pumps for my new Mrod and it died. It pumped up the rifle tank on the first two sessions but it was difficult to use and made an odd slurpy noise.

On the third use it lost pressure and failed to pump up. I could hear an air leak when I pumped. Since my pump came with some (not all) o-rings I decided to take it down and see what the issue was. Note: No condensation or water anywhere in the pump.

One of the small o-rings failed. I'm not sure why this took place so I just cleaned all the pump internals and sealed it back up. I had some Crosman Silicon chamber lube for the o-rings.

After the clean and seal job the pump worked much better. The strokes were very smooth from top to bottom and it seemed to pressurize much faster until it got upwards of 2k psi.

I think I counted about 80 strokes to achieve 3k psi after starting at about 1900 psi.

I just hope it keeps working. It's now very easy to use and I'm an old guy.

  • Florida, Panama City
Benjamin Marauder .22
RWS Diana 45 West Gemany .177
Benjamin Trail NP .22

Offline stretch

  • Sharp Shooter
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Re: Hand Pump Died
« Reply #1 on: February 18, 2019, 04:09:11 PM »
I recently bought one of the affordable Chinese hand pumps for my new Mrod and it died. It pumped up the rifle tank on the first two sessions but it was difficult to use and made an odd slurpy noise.

On the third use it lost pressure and failed to pump up. I could hear an air leak when I pumped. Since my pump came with some (not all) o-rings I decided to take it down and see what the issue was. Note: No condensation or water anywhere in the pump.

One of the small o-rings failed. I'm not sure why this took place so I just cleaned all the pump internals and sealed it back up. I had some Crosman Silicon chamber lube for the o-rings.

After the clean and seal job the pump worked much better. The strokes were very smooth from top to bottom and it seemed to pressurize much faster until it got upwards of 2k psi.

I think I counted about 80 strokes to achieve 3k psi after starting at about 1900 psi.

I just hope it keeps working. It's now very easy to use and I'm an old guy.

I got two uses out of mine before it started leaking water bad.  I really need to rebuild mine.  Hopefully it wasn't a complete waste of money and a rebuild will bring it back to life.
  • Outer Banks, North Carolina
"We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution."  Abraham Lincoln

Air:
Benjamin Discovery .22, Vortex Crossfire II 4-12x44  (loving this rifle!)
ATI Vista Liberty .22, Vortex Viper HS-T 6-24x50 (testing now)

Powder:
Armalite M-15 18" competition, iron sights
CZ 455 Varmint .22lr Nikon 6-18x40
Savage Mk II .22lr BSA 3-9x40

Offline Pellet Fun

  • Plinker
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  • Posts: 200
  • yes
  • Real Name: Gary
Re: Hand Pump Died
« Reply #2 on: February 18, 2019, 06:25:26 PM »
After digging into the pump the mechanics are very simple. I believe what happened was when they assembled my unit it was done hastily and in so doing they damaged that small o-ring in the attached photo. If you blow up the photo and look inside you will see where it was cut.

Also, the pump assembly lube is some kind of nasty stuff. Once I used a quality silicon it seems to be great. I may buy a spare.

Also, you don't need the water.
  • Florida, Panama City
Benjamin Marauder .22
RWS Diana 45 West Gemany .177
Benjamin Trail NP .22

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