Hand Pump Vented Black Slime. Pending Failure?

[mwgm2020]

I just topped off my rifle using my cheap Chinese Amazon hand pump, and when I vented the pressure relief my hand was sprayed with black oily sludge.  I am guessing the black is coming from a degrading o-ring, oil, and water and I am looking at a rebuild in the near future.   I did a partial break-down and cleaned it out as best I could, and put some Super Lube multi-purpose grease on the outside tube.

Any insights, ideas, or advice?

[B.Guns.]

When I got my Chinese pump I tore it down and cleaned all that goo out of it and lubed it with a little silicone oil.
The pump works really well. I think its some kind of assembly grease.

[mwgm2020]

When I got my Chinese pump I tore it down and cleaned all that goo out of it and lubed it with a little silicone oil.
The pump works really well. I think its some kind of assembly grease.

I've had this pump since May and this is the first time it spit that dark goo.  I partially disassembled it and cleaned out what I could and then re-lubed using Super-Lude O-Ring lube "oil".

One problem I have is the Chinese instructions are incomprehensible and there no diagrams.  I don't want to take the pump apart without understanding how it is built.

When I got it the instructions said I should add oil into the top, so I used Pelgun oil because I didn't know any better at that point.  I wondering if that played a part.
 

[mwgm2020]

When I got my Chinese pump I tore it down and cleaned all that goo out of it and lubed it with a little silicone oil.
The pump works really well. I think its some kind of assembly grease.

I've had this pump since May and this is the first time it spit that dark goo.  I partially disassembled it and cleaned out what I could and then re-lubed using Super-Lude O-Ring lube "oil".

One problem I have is the Chinese instructions are incomprehensible and there no diagrams.  I don't want to take the pump apart without understanding how it is built.

When I got it the instructions said I should add oil into the top, so I used Pelgun oil because I didn't know any better at that point.  I wondering if that played a part.

I just found this on youtube


It appears to the same as my unit.  I had no idea there was water in it.  The manual mentioned "no need to add water" but that did not make sense to me. 

[Bentong]

I replaced water with 50/50 coolant since 2014 when I got it and might be time to flush and refill it. Last week my Maximus sprung a leak from the foster fitting and just need to replace the o-ring and saw no corrosion from pumping it. I use shock silicon oil on the shinny parts of the pump. I got 2 back up pump and was wondering when they'll get their turn. 🤔

[Kerplink]

I replaced water with 50/50 coolant since 2014 when I got it and might be time to flush and refill it. Last week my Maximus sprung a leak from the foster fitting and just need to replace the o-ring and saw no corrosion from pumping it. I use shock silicon oil on the shinny parts of the pump. I got 2 back up pump and was wondering when they'll get their turn. 🤔

Why is the coolant better than pure water? Are you concerned the water might boil? Or are you worried about corrosion? Because coolant actually reduces the thermal transfer vs. pure water.

[Eddie_E]

The water cooling thing was a myth that came from one Chinese middle-man. 99% of us use no water.

Just rebuild with everything clean and dry using 30 wt silicone RC shock oil then once a month put one small drop of the silicone oil on the center 5mm rod by holding the outer tube and unscrewing the T-handle. If the outer tube starts to feel sticky in a few months, put one drop on the outer bottom tube and cycle 3 times while spinning and wipe dry.

[OTmachine]

I put the coolant in mine and reduces the chance of corrosion in that one area.  Helps to slow down the temperature rise, (what can it hurt?).  Not a whole lot to go wrong with a hand pump IMHO.  Basically, just o-ring seals.  And I have a large assortment from my hobbies and everyday work.

[nervoustrigger]

For what it's worth, I've seen a black discharge from one that I had installed a Viton O-ring for the final stage.  It suffered abrasion failure after a short time, and I presume the discharge was the O-ring material sloughing off.  It wasn't a lot but enough to notice it on my hand after briskly releasing the bleed screw.