Recently my Four Uncles hand pump has been acting up. When I go to pump up the PCP, air is going into the gun's air cylinder, but my pumps outer tube ; the one with the attached handle rises up the shaft when I stop pumping in order to check the gauge pressure. It rises about a foot or so above the base by itself. It's like the pressure from the hose is seeping into the pump to cause it to rise. I took off the main tube and cleaned and lubed the o-ring on the check valve to no avail. The pump doesn't leak air and it's able to fill up the PCP. I'm thinking it might be an o-ring issue in the third stage piston rod. Has any member on this forum encountered this phenomena?
Four Uncles Hand Pump Issue
- Thread starter megiddo65
- Start date
Mine did same thing from day one, thought they all did. Check out Coby Leo's (Topa Manufacturing Company) 2-part YouTube video series on repair of Chinese hand pumps, you'll be glad you did. WM
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I actually have both of these videos on my laptop. Coby just talks about disassembly, cleaning, lubing, refilling coolant, and reassembly. What did you do to your pump to stop the outer tube from rising? My other pump(GX, H4 Hand Pump) doesn't do this.
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It is the tiny o ring on the check valve in the square base. You have to take the whole thing apart at the base not just the handle and 1st stage although I'm sure that helped prolong that parts life.
I have this 4 stage pump and mine did the same thing after a bit. Changing that tiny o ring on the tip of the brass cone shaped check valve fixed the handle rise and also it was way easier to pull the pump back up.
I've had to do mine twice since owning mine since November last year but it isn't terrible my pump came with the wrench to take the base nut off and unscrew the whole outer tube and then the inner ones to get to that check valve.
It is part #9 in this photo.
But I can't confirm those sizes are the ones you need for your specific pump. My pump came with extras so I just swap out.
It'll be obvious cause the o ring will be smashed or chewed up. Those 2 reasons were why mine had those symptoms.
I have this 4 stage pump and mine did the same thing after a bit. Changing that tiny o ring on the tip of the brass cone shaped check valve fixed the handle rise and also it was way easier to pull the pump back up.
I've had to do mine twice since owning mine since November last year but it isn't terrible my pump came with the wrench to take the base nut off and unscrew the whole outer tube and then the inner ones to get to that check valve.
It is part #9 in this photo.
But I can't confirm those sizes are the ones you need for your specific pump. My pump came with extras so I just swap out.
It'll be obvious cause the o ring will be smashed or chewed up. Those 2 reasons were why mine had those symptoms.
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Likewise, every time I’ve had this problem it has been solved by getting to the small valve and o ring mentioned above. So far cleaning has been enough to fix the issue
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Sorry, mis-read post, thought you were referring to handle, my mistake, was getting late. Coby Leo's videos mention check valve cleanings in pump and base, thought might be helpful place to start. WM
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You need to replace the small o ring you cleaned. Not sure on the size as I haven’t had to mess with my 4 uncles pump yet. I’m guessing it is the same as all the other China pumps. My other pumps I think i put an 006 size oring in them. Not positive but you can order a whole bag of 006 and 007 from Amazon super cheap and see which size works best. I can’t remember for sure which it is. They don’t last super long but you can get 100 for like 5 dollars and it’s a super quick change out.
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Thank-you members for the quick and informative response and diagram. I went back and unscrewed the whole outer tube mechanism from the base to get to the brass like valve with the o-ring that I had cleaned previously. After removing the o-ring, I inspected it and noticed the top side, inner diameter ring was scarred from use. I replaced it with the provided o-ring from the manufacturer and screwed the parts back into place. Did a test run with the plug and voila, it WORKED. I went back and watched a video that I had downloaded in the past onto my laptop that member "WorriedMan" had mentioned on this informative thread. It's a two part video about 6-7 minutes each. It describes the whole disassembly, re-assembly, cleaning, lubing, and adding coolant to these China made pumps. Great to refer to if you are troubleshooting.
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Megiddo,
Agreed, Coby Leo's videos, after watching a few times, gave confidence to find reason for my hand pump's overheating. At same spot in video where Coby tips pump over and collects coolant in cup, for me, nothing came out! Turns out coolant had never been added. Four ounces of mineral oil made a world of difference, but super-heated air introduced earlier had brought damaging moisture to my Gauntlet, so moved on to Yong Heng. I've borrowed gauge, fill whip and cotton filter for Yong Heng, but could resurrect hand pump in emergency. Think any Chinese hand pump owner owes it to themselves to watch Coby's videos. WM
Agreed, Coby Leo's videos, after watching a few times, gave confidence to find reason for my hand pump's overheating. At same spot in video where Coby tips pump over and collects coolant in cup, for me, nothing came out! Turns out coolant had never been added. Four ounces of mineral oil made a world of difference, but super-heated air introduced earlier had brought damaging moisture to my Gauntlet, so moved on to Yong Heng. I've borrowed gauge, fill whip and cotton filter for Yong Heng, but could resurrect hand pump in emergency. Think any Chinese hand pump owner owes it to themselves to watch Coby's videos. WM
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My sentiments as well. I know one day I will have to take the whole pump apart and these videos will be my saving grace. It doesn't surprise me as they failed to add water or coolant in the pump. I bought a Vevor pump to be the back-up to my Four Uncles, but it spewed glycerin from the pressure gauge on my first test run. At the same time, it was dumping all the air I filled into my PCP when I bled the valve. Turns out that the bleed valve on the pump was not venting the built up air quick enough to allow the valve in my PCP air cylinder to close. I ended up getting a full refund from Amazon on that lemon. The quality control on some of these China made pumps are questionable.
After dumping the Vevor, I bought the GX, H4 hand pump that's solid & sturdy and works like a charm. I've had no problems or beefs with this product that also happens to be made in China, but the quality control is present as their pumps come with a "Qualified Certificate." This pump is my "Go To" pump and my Four Uncles is the back-up now.
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