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Support Equipment For PCP/HPA/CO2 and springers ,rams => Support Equipment For PCP/HPA/CO2 => Topic started by: Gear_Junkie on February 17, 2018, 12:51:27 PM

Title: Help with Hand Pump Rebuild - Not Building Pressure
Post by: Gear_Junkie on February 17, 2018, 12:51:27 PM
So, I just rebuilt my Chinese Ebay hand pump.  I changed out the damaged O-rings and lubed everything with silicone grease and oil.  It's all back together, but it's not building pressure.  I can hear air being sucked in the port by the grips, and hear air coming out this same port on the down stroke.  Can anyone tell me what I did wrong?

Thanks!


**UPDATE 1**
It WILL build pressure, but the first few strokes need to be very fast.  This leads me to believe that something is sticky - like I should have used oil in a place where I used grease :-\


**UPDATE 2**
All is good now.  The pump now builds pressure starting with the first pump.  I'm not sure what happened, but I'm glad it resolved itself - this almost never happens!   :D
Title: Re: Help with Hand Pump Rebuild - Not Building Pressure
Post by: mobilehomer on February 17, 2018, 01:41:40 PM
You probably got a little too much grease on the top check valve and it took a few pumps to clear it. How smooth is it now? Compared to before.
Title: Re: Help with Hand Pump Rebuild - Not Building Pressure
Post by: Gear_Junkie on February 17, 2018, 02:25:16 PM
Quote from: mobilehomer on February 17, 2018, 01:41:40 PM
You probably got a little too much grease on the top check valve and it took a few pumps to clear it. How smooth is it now? Compared to before.

There are a couple minor sticky points in the stroke, but it does pump much easier. 
Title: Re: Help with Hand Pump Rebuild - Not Building Pressure
Post by: hollowpoint1911 on February 17, 2018, 02:35:29 PM
Though it sounds like you got things working, just wanted to add my experience.

When I first serviced my Chinesium hand pump, I made the mistake of using silicone grease and had the EXACT same outcome as you. After diddling around with checking for loose connections, pinched orings, etc, I tore it back down and removed all the grease I could. I relubricated everything with 30w silicone oil and that fixed it. Silicone grease is just too viscous IMO, and I think the reason your pump resolved itself is because you ended up pushing the grease out of the way.
Title: Re: Help with Hand Pump Rebuild - Not Building Pressure
Post by: Tweeter on February 17, 2018, 03:40:47 PM
Quote from: hollowpoint1911 on February 17, 2018, 02:35:29 PM
Though it sounds like you got things working, just wanted to add my experience.

When I first serviced my Chinesium hand pump, I made the mistake of using silicone grease and had the EXACT same outcome as you. After diddling around with checking for loose connections, pinched orings, etc, I tore it back down and removed all the grease I could. I relubricated everything with 30w silicone oil and that fixed it. Silicone grease is just too viscous IMO, and I think the reason your pump resolved itself is because you ended up pushing the grease out of the way.

+1 had the same experience with my hill pump.  In my experience you can use silicone grease on everything but the high pressure o ring (usually a small green o ring), I had to use silicone oil on that one or the pump handle was very hard to pull up and push down.