Not sure what's going on!? (With my Benjamin Hand Pump).

[kmd1984]

I use a Benjamin hand pump to fill my FX Bobcat Mk2. I usually pump for a few minutes and then take a break for a few. This newer had been a problem. However, as of lately, whenever I take a little break and then come back, my hand pump is fully extended, and it's really hard to push down on it. Not only that, but when I then try pulling up, it feels like there is a vacuum building, which makes it really hard to pull up. I usually power through this and after a while everything is back to normal.

That said, the pump would never do that. This is a recent development.

Thanks,

Kmd

 

[BigTinBoat]

It's likely the o-ring in final stage leaking.

In the below video you will see the part at 3:01 mark

 

[kmd1984]

Do you mean the Viton o-ring!? I see now o-ring at 3:01. Anyhow, thank you for the input. At least I know now that it is the pump and not the gun.

 

[BigTinBoat]

"kmd1984"Do you mean the Viton o-ring!?

Yes - it's a -007. You may want to get what they call "x" rings, or "Quad" rings

 

[kmd1984]

This is my first pump... can I simply Google those parts, or do you happen to have a good source!?

Appreciate the help.

Kmd

 

[BigTinBoat]

I use theoringstore.com or oringsandmore.com

This is the size that fits that final shaft

http://www.oringsandmore.com/x-rings-size-007-price-for-20-pcs/

 

[kmd1984]

Thanks...!

 

[Vince_Diesel]

After the pump rebuild, pump no more than 30 times, let the pump cool down for about a minute then repeat. I have found you will get more use between rebuilds if you don't overheat the rings.

 

[BigTinBoat]

"Vince_Diesel"After the pump rebuild, pump no more than 30 times, let the pump cool down for about a minute then repeat. I have found you will get more use between rebuilds if you don't overheat the rings.

Good tip, and it also helped me when I switched from Silicone Grease to Silicone Oil for lubing

 

[kmd1984]

"Vince_Diesel"After the pump rebuild, pump no more than 30 times, let the pump cool down for about a minute then repeat. I have found you will get more use between rebuilds if you don't overheat the rings.

Most of the time I pump in between doing something else. So I do not sit there, pump, take breaks and then go back to pumping. That said, my pump gets around 5 minutes of cooling down time after 25 pumps... So I should be good. The only question is, what is the average time I can expect between rebuilds?! I had this pump for almost 4 month and used it probably not more than 20 times...

thanks,

Kmd

 

[kmd1984]

"BigTinBoat"

"Vince_Diesel"After the pump rebuild, pump no more than 30 times, let the pump cool down for about a minute then repeat. I have found you will get more use between rebuilds if you don't overheat the rings.

Good tip, and it also helped me when I switched from Silicone Grease to Silicone Oil for lubing

Lubing what?! During the rebuild or afterwards?!

thanks,

Kmd

 

[kmd1984]

BTW, I wonder what Walmart is going to do when I bring it back and tell them it wont work anymore!?

 

[BigTinBoat]

"kmd1984"

"BigTinBoat"

"Vince_Diesel"After the pump rebuild, pump no more than 30 times, let the pump cool down for about a minute then repeat. I have found you will get more use between rebuilds if you don't overheat the rings.

Good tip, and it also helped me when I switched from Silicone Grease to Silicone Oil for lubing

Lubing what?! During the rebuild or afterwards?!

thanks,

Kmd

Both - When I get pump out to use I wipe shaft clean and then put a couple drops of oil on shaft and spread it around with my finger. Makes pumping much smoother.

 

[kmd1984]

"BigTinBoat"

"kmd1984"

"BigTinBoat"

"Vince_Diesel"After the pump rebuild, pump no more than 30 times, let the pump cool down for about a minute then repeat. I have found you will get more use between rebuilds if you don't overheat the rings.

Good tip, and it also helped me when I switched from Silicone Grease to Silicone Oil for lubing

Lubing what?! During the rebuild or afterwards?!

thanks,

Kmd

Both - When I get pump out to use I wipe shaft clean and then put a couple drops of oil on shaft and spread it around with my finger. Makes pumping much smoother.

Copy that... thanks.

 

[kmd1984]

Trying to rebuild my pump I scrat c h the main cylinder. Any idea how to get that scratch out!? 1500 sandpaper maybe?

Thanks,

Kmd

P.s. I should check Walmart first and see if they take it back. I mean, how can a pump fail after 3 month!?