Pump Cup or Check Valve Problem?

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Sierra_Roadrunner
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Pump Cup or Check Valve Problem?

#1

Post by Sierra_Roadrunner »

While pumping what causes the pump to sometimes loose traction? In other words while pumping I can feel some resistance on some down strokes and then all the sudden on a down stroke the pump suddenly slides for several strokes before it catches again.. The leather pump cup looks fine no rips or deformities that I can see. And the bore is smooth. This is happening on a 220H and a 242C with their own separate pump plungers.
Is this caused by the pump cup itself or is there a problem with the check valve sealing?

TIA
Joe
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" Curiosity is natural to the soul of man and interesting objects have a profound influence on our affections." - Daniel Boone
Sam_McCord
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Re: Pump Cup or Check Valve Problem?

#2

Post by Sam_McCord »

You may need to oil the pump cup if you haven't. Should be soft enough to expand and seal on down stroke. Use neatsfoot oil if you have it but I've used 10-40 and even CLP occasionally and they worked just fine.
Doug

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Chucker
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Re: Pump Cup or Check Valve Problem?

#3

Post by Chucker »

Pump cup.
Chuck
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Tgarner01
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Re: Pump Cup or Check Valve Problem?

#4

Post by Tgarner01 »

I had this happen recently on a pump that appeared to have a good leather cup, but I replaced it anyhow with a new one and it was doing the same thing... Ended up being the surface the cup flat was sealing against (the flat that supports the cup) causing air to bypass once in awhile. No better way to break a mantle than a pump that works one time, and not the next...
Toby Garner, from SW Missouri
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JimL
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Re: Pump Cup or Check Valve Problem?

#5

Post by JimL »

I agree on the oiling. Remove the pump and work the oil into the leather, and then mushroom out the cup.
-Jim

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Sierra_Roadrunner
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Re: Pump Cup or Check Valve Problem?

#6

Post by Sierra_Roadrunner »

Thanks guys. Looked like the cup was pliable enough but by the consensus here I'll soak it in Neatsfoot oil for a while, massage it in and try again.
Appreciate all your help.
Joe
ICCC# 1893

" Curiosity is natural to the soul of man and interesting objects have a profound influence on our affections." - Daniel Boone
425E
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Re: Pump Cup or Check Valve Problem?

#7

Post by 425E »

I found out on a stove I had problems with. That I hand to mushroom the pump out by slightly spreading the leather from the inside toward the outside. Just make sure you pump leather is oiled good. After stretching the pump leather gently form it to tube as you reinstall the pump. Mind worked perfectly after I did this. JImL help me save my stove when I was repairing it. When I followed his instructions.
brokenmantle
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Re: Pump Cup or Check Valve Problem?

#8

Post by brokenmantle »

when mine do this, the cup is too pliable.
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Sierra_Roadrunner
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Re: Pump Cup or Check Valve Problem?

#9

Post by Sierra_Roadrunner »

Neatsfoot oil and some massaging did the trick just like you all suggested. Thanks a ton for helping out. Now that I have pressure I'm lucky enough to get to replace the valve packing. The nut is already tightened to the max and still seeps air. I have packing on hand thanks to Mike at OCP from an order I placed several months ago. One never knows when fettling with these what might happen next so it's nice to have an extra this, an extra that on hand just in case.

Cheers
Joe
ICCC# 1893

" Curiosity is natural to the soul of man and interesting objects have a profound influence on our affections." - Daniel Boone
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