PCP Handpump - No coolant in cylinder?

[Bugman]

My relatively new hand pump (off ebay, stainless steel 4500 psi), seems to have issues in pumping. The primary pump with handle goes down fine but just seems to return right back up without delivering much air and struggles mightly against any pressure. I took it apart to repair seals but in all the videos and the ebay description there is supposed to be a coolant inside the inner tube. There is nothing but air. Should I refill it with antifreeze or just water after I repair everything?

PCP Airgun Hand Pump High Pressure Hand Pump for Benjamin Hatsan HPA 4500psi 278716861301 | eBay

 

[hawkeye69]

I'll let someone who has a hand pump respond more fully but... do not add any liquid to your pump. You only want dry air going into your gun.

 

[vinny]

I’ve owned a few hand pumps including the hill. None have had coolent inside of them , there used to be a video of some Chinese guy saying he does and shows how he did it, I wouldn’t recommend it at all.

 

[ImpactX]

Lmao coolant in hand pumps? Who told you that? Lol. Remember everything you see on the internet isn't real. Yeah put coolant inside the hand pump, seal it and try pumping it. Lol. But seriously, hand pump only need silicone grease on the o rings and seal it back. Usually when the pump won't pump much to little air, it's the tiny o ring on the piston rod that needs to be replaced. 

 

[MrHomebody]

I bought the HPA Hand Pump off E-Bay, watched the 3 Youtube videos on disassembly and repair then added Mineral oil as a coolant. You should too.

Like @ImpactX above said, "it's the tiny o ring on the piston rod that needs to be replaced"; which is exactly what adding the coolant protects against.

 

[xsarfc9x]

I used computer coolant in mine. The tube you put it in is sealed off from the air that is being pumped. Never had an issue with it leaking and I was able to keep the temperature of the pump cooler longer then the pump that did not have it. 

 

[OTmachine]

This guy, Christopher Moore, shows repair on Youtube using antifreeze: https://www.youtube.com/watch?v=_R2aiKOQDuo

Works Good! My son’s Hill Mk4 pump could not compete with my Chinese Amazon pump rebuilt this way.

Coolant definitely helps. Great Video. If your handle is pushing back up, the check valve in the base is sticking. My .02

 

[Kevin23]

My relatively new hand pump (off ebay, stainless steel 4500 psi), seems to have issues in pumping. The primary pump with handle goes down fine but just seems to return right back up without delivering much air and struggles mightly against any pressure. I took it apart to repair seals but in all the videos and the ebay description there is supposed to be a coolant inside the inner tube. There is nothing but air. Should I refill it with antifreeze or just water after I repair everything?

PCP Airgun Hand Pump High Pressure Hand Pump for Benjamin Hatsan HPA 4500psi 278716861301 | eBay

I would say more likely user error, they are fussy about how fast/hard you pump. You should be able to hear the air go "woosh" past the valve at the end of your down stroke (only a tiny bit of air leaves the pump on each stroke). Too slow on the downstroke and it will not compress and force the air forward in the line, if you dont pause for a split micro second as you bottom out the pump (pumping too fast) then the air will just kick the handle back up instead of pushing the air through the valve. 

Should hear the woosh of the air going through the valve on the last inch or two of your downward stroke, then hear it take a big gasp of air as you come back up and repeat. Pause for a split second again at the very top to let it suck in all the air it can. This isnt like a bicycle pump, up down up down up down doesnt work.. Down, pause, up, pause, repeat. 


Cooling the pump shouldnt matter, your hand pump should never get hot. If it gets hot then you dont have enough lube and are pumping way too fast. Hand pumps are for convenience and economics savings, not speed or easy filling. It will get warm to the touch for sure, thats what happens when you compress air.. but should never be even close to hot enough to burn seals or cause a difference in operation. Lots and lots of silicone oil, and a good oil/moisture filter. 

 

[Bugman]

My relatively new hand pump (off ebay, stainless steel 4500 psi), seems to have issues in pumping. The primary pump with handle goes down fine but just seems to return right back up without delivering much air and struggles mightly against any pressure. I took it apart to repair seals but in all the videos and the ebay description there is supposed to be a coolant inside the inner tube. There is nothing but air. Should I refill it with antifreeze or just water after I repair everything?

PCP Airgun Hand Pump High Pressure Hand Pump for Benjamin Hatsan HPA 4500psi 278716861301 | eBay

I would say more likely user error, they are fussy about how fast/hard you pump. You should be able to hear the air go "woosh" past the valve at the end of your down stroke ...

I wish that was the case, but familiar enough with the pumping motion and sound that should occur. My guess is that a pump stage isn't delivering enough to open the check valve and then reseal it against the line pressure since I don't have any relief from the pump pressure out the hose. It just binds up and the handle will rise all the way up. Spent an entire day trying to rebuild it with no joy. Finally had to start drinking....heavily....ordered Yong Heng....but still will like to fix this in the interim.

 

[DesertSilver]

Sounds like maybe the check valve at the bottom of the pump.