Author Topic: rebuilding a cheap hand well pump  (Read 2441 times)

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dnix71

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rebuilding a cheap hand well pump
« on: November 04, 2009, 07:29:51 PM »
I live on a canal, but wanted cleaner water for my vegetable garden. The $20 hand well pump made in China looks nice and threads directly to the 15' deep 1 1/4" sand point well I hammered one weekend, but it doesn't actually pump water, as Lehmans warns in their online ad.





Internet reviews on this pump are poor, but there just isn't anything for less than about $150 that sounds like it actually works, so I set about in my spare time rebuilding the pump until it does actually pull water from a shallow well. It has to be primed with a couple of cups of water. Getting the water up past the bottom flap without priming is something I haven't been able to work around.


You'll need the following tools: a hacksaw, decent fabric scissors, pencil, a pair of pliers, a small flat tip screwdriver,  a couple of small pieces of thin soft leather (I bought the $7 Tandy leather trim 3-piece assortment at a local craft store), and probably a 12 x 1.75mm die.


If you have mineral oil in the medicine cabinet you can use that to help preserve the leather once the pump is reassembled.


First check the piston throw by raising and lowering the handle. If the piston bottoms out on the check valve before the handle is fully raised, or doesn't come all the way up when the handle is lowered, you will need to add threads to the connecting rod. I needed to add 1 inch of threads to mine. The connecting rod then must be shortened so it doesn't interfere with the check disc inside the piston assembly. I needed to hacksaw off 5/8".


There is a bolt at the back of the pump cap under the handle. Loosen that and lift up to pull out the the piston assembly. After you have adjusted the piston throw unscrew the bolts on either side of the base and remove the bottom flapper/check valve.


Remove the metal disc and put the screw/washer/nut back in the tongue but don't tighten the nut too much. Make sure the tongue lays flat and bend it down sharply by hand if necessary. Use lock-tight on the screw if needed to avoid overtighting. This check valve design is mediocre and if you tighten down the outside base screws too much it won't lay flat and seal. The flapper seems to work better without the metal disc because the disc isn't flat and that prevents a good flapper seal.


Next remove the rubber cup by pulling sideways to peel it out, then undo the twist lock base of the piston assembly. Don't lose the check disc. You probably won't be able to undo the twist lock with the cup in place, it looks like they used a special slotted tool and press at the factory.


Make leather donuts in place of the rubber cup. I needed 3 stacked for the proper thickness. The leather has to be thick enough to be difficult to reassemble the twist lock and a snug fit inside so there is nowhere for air to leak around the parts when reassembled. Don't make the outer diameter too big or when the piston is reinserted in the pump bore the new cup will interfere with the check disc. Make sure you have the check disc back in correctly before you reassemble the piston halves because it will be difficult to separate them again without that factory tool.


Reassemble the base, then oil the cup and push it down from the top. Tighten the screw behind the handle top and you are ready to go.

« Last Edit: November 04, 2009, 07:29:51 PM by (unknown) »