Water system pressure has been weakening for years, so that whenever I use
even a couple gallons of water the pump cycles for a minute or so. Last
Thursday I had no water and the pump had lost its prime. (Note: ancient,
possibly 50-y/o Goulds 8165 1/2 hp jet pump in sub-cellar, well depth around
25 ft, piping is 1.25 in. cast iron). Lots of possible problems at this
1. Tried to re-prime pump, got weak water pressure, never over 32 lbs. and
pump stayed on for 1/2 hour even with no water running in house. I shut it
off, and it lost prime again. Tried to fill it up but water bled back down
into well. Diagnosis: bad check valve.
2. Saturday, replaced check valve and connecting nipples on either side. Old
nipples had crumbled, rusted threads and there were big bits of rusted iron
in the old check valve. Made sure that new valve was installed in the right
direction. Also installed a bit of clear pipe between pump outlet and copper
pipe leading to pressure tank. Pump took and held prime, but would not build
pressure and moved no water. There are air bubbles going through the clear
pipe. Figured there was air behind the check valve, removed check valve and
backfilled piping into ground from neighbor's hose. Reconnected everything,
same problem. Possible diagnosis: old union leaking air?
3. Today installed new union and nipple leading directly to pump, and new
pressure gauge to ensure I'm getting the truth. Now all piping from elbow
before check valve to pump is new. Pump takes and holds prime and is moving
water but doesn't exceed 20 psi and loses that after a few minutes. The
clear pipe shows a few air bubbles for the first minute or so but then a
solid column of water moving through, with hardly any bubbles. Water flows
weakly from spigots on first floor, fortunately enough to take a quick
shower. If a first floor tap is shut off and then re-opened, pump loses
pressure to down below 10 lbs. and bubbles reappear in the clear pipe.
Diagnosis: pump is bad, need to buy new pump.
What could I be getting wrong here - are there other possibilities? New
pump will be $300, if the real solution is cheaper, I'm all ears and very
grateful to the correct adviser.