Hand pumps tell me what I'm doing wrong ??

[latenighthunter2000]

I joined here about a year ago here looking for advise, and with that advise and research I'm now an owned of a Benjamin Bulldog (added pit bull barrel supports and suppresser) all good there. Now my problem, I purchased a Benjamin hand pump and worked great for a couple weeks and than just no more air ? than a Air Venturi G9 lasted a week same, I'm I doing something wrong or do i need a better pump, thanks for any and all help.

Also i have been casting muzzle loader balls for years, thinking of casting lee mold 90305 .356 102gr bullets for my Bull Dog any advise there

 

[UCChris]

Are you letting the pump cool down or are you just pumping in one quick session? If you heat the pump up and don't keep the main shaft lubed, the pump will die early.

 

[WorriedMan]

My $50 Chinese handpump lasted about as long. Went to YouTube and watched 2-part video by Coby Leo, employee of Topa Manufacturing Company, guys who make these, titled, "How to Repair the 300bar 4500psi Air Rifle Hand Pump." (4/22/20) Found out my pump, listed as water-cooled, never had coolant installed. I'd overheated it, even using recommended 40 pump, 15 minute cool-down, 40 pump, 15 minute cool-down routine. Watched couple times, then fixed mine with parts and tools provided with pump. Best of Luck,

WM 

 

[Healthservices]

At what pressure is it stalling at? Is it building any pressure at all? I'm still learning with my two.

If no pressure at all you have a leak. 

If it builds pressure and drops and goes back up a little more then it maybe because you are not pushing the pump all the way down so the air goes into next chamber.

Be careful where you put down your pump. On most cheap pumps the intake is at the top of the pump shaft right under the handle between the bolts that hold the handle on. It just needs a speck of dirt in one of the o rings to make the pump useless.

If it stalls at a like 3500 psi then most likely there is dirt in the chamber with the metal rod. I found a little metal in mine.

There is also a seal at the bottom that gets dirt in it and causes air to leak back into the prior chamber. 

Although it may seem intimidating just look at a couple you tube videos to help you tear down and put back together your hand pump. Its not that bad. 

 

[John "spysir" Blount]

You do not need a "better pump". Just the fact you went through 2 SO fast (my old AV Gen4 is 5+ years old & going strong, as is the $50 Vevor).

I'll ask about cool down also, when hand pumps came out both makers recommended 50 (fifty) strokes then a 5 min. cool down (with handle up). With a 500cc rig it does take a while but pumps last years and years that way.

Seems like at least the AV should be under warranty? 

John

 

[MadKatt]

 My MK5 works great as stated keep shaft orings lubed. I pump 60-80 pumps over about 3 minutes pausing at the up stroke and down stroke then let pump cool for around 10 minutes feeling the pump shaft to make sure it’s not warm to the touch. I then add another 50-70 pumps it fill either of my pcp guns one is a 250 bar max the other is 300 bar max. I never let my guns get below 120-130 bar.

 

[pcwhite]

I usually only go up to 200-210 bar with mine and take breaks every 20 or so pumps. I reload magazines in between. So far it's been fine for over a year. Maybe just take some breaks pumping.