Well Pump Problem - Need Help

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jobondur

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I have a Grundfos JP-7 pump hooked to a AO Smith 3/4 hp single phase motor wired for 220 (model C48K2DB11A16). When I went to start it up this spring it just hummed so I replaced the capacitor but that didn't fix it. I then pulled the motor from the pump and turned the impeller a couple of times by hand to break it free. That seemed to work as it then started but after a month or so it started making a sound like it had bad bearings. So I disassembled the motor and the front bearing was shot. I replaced both bearings with Timken bearings and replaced the pump seal with one from Amazon. I reinstalled everything and it just hummed, didn't run. I pulled it off the pump housing and checked everything and then bench tested the motor. The motor runs fine not connected to the impeller but when I put the impeller back on it seems to tighten down so much that it compresses the pump seal and ruins the seal. The order of assembly for this on the pump end is as follows:
  1. Motor with pump mounting plate installed
  2. Sling ring
  3. Seal plate
  4. Shaft seal (white part)
  5. Shaft seal (carbon ring - with carbon ring mating with white part)
  6. Large washer
  7. Impeller (no screw or nut securing back of impeller)
  8. Pump housing gasket
  9. Main body of pump housing and connector ring
I haven't messed with the pump housing at all and I have primed the pump as required. I pulled everything back apart and ran it with the impeller installed without tightening it much and ran it not connected to the pump housing so I could observe it, knowing that I would likely ruin the seal due to lack of water/cooling. When I did that, I could see the impeller tighten down on the shaft and then the seal started smoking and cracked from too much friction. I checked for shaft runout and got at max 0.001" of deviation when turning it by hand and measuring with a dial indicator. The only thing I know of that is wrong with the motor is I did break off a small section of one of the fins of the fan. That being said, the motor runs very smooth when not connected to the impeller. The only part I'm not 100% sure of is the placement of the large washer (#6) but I'm about 95% sure of that because its the only place it really fits and it had wear marks that line up with putting it where I have it, so pretty sure it's correct. The motor turns easily by hand with the impeller not cranked down on the shaft. Once it runs for a bit, the shaft will not turn easily by hand as the impeller tightens down to the point it compresses the shaft seal too much and binds against the shaft (at least that's my theory).

I've tried 3 different capacitors and 2 different shaft seals (same specs, just different mfrs) with no luck. What's going on? Any advice/troubleshooting tips are appreciated.
 

WorthFlorida

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The motor windings are bad. When it was locked up it burned. All motors have a locked rotor rating and to prevent the motor from catching fire. During the lock the motor can still get very hot and do damage.
One clue it it spins without a load but a little pressure there isn't enough torque to get it going.
 
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Valveman

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You can check for a short in the windings with an ohm meter. If the windings are still good, I am thinking something is wrong with the assembly you made. The impeller should not tighten further when the pump runs. The impellers should be locked in place on the shaft. Maybe a spacer missing between seal and impeller, as they should not touch.
 

jobondur

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Ok, so I watched some YouTube videos and THINK I tested the motor windings correctly (please confirm I did it correctly or tell me what I did wrong). I removed the three wires from the start capacitor (2 yellow and 1 red) and put my multimeter on the Ohms 200 setting (lowest setting) and touched the two probes together and got 6 Ohms baseline. I then tested between the red and each of the yellow wires. The test between red and yellow #1 gave me 18 ohms (i.e. good winding). The test between red and yellow #2 gave me an open loop reading (i.e. bad winding). That being said I guess I need a new motor, correct? What exactly do I need to look for to find the right motor to swap out here? Can someone recommend a good but cheap replacement motor. I'm going to be selling the house in a year as we're currently building a new house and want to invest as little as possible.

Now that being the case, I don't want to install a new motor and burn it out because something is causing the impeller to bind. So now I have to figure out what's going on with the impeller. Could it be that I'm using the wrong shaft seal and the spring isn't compressing as much as the old one? HERE is the one I used. I couldn't get a part number off the original one but this one seems to fit properly and is the same basic size and design as the old one.

Any assistance is greatly appreciated as I've been battling this thing for a couple of weeks now.
 

jobondur

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Any that you'd specifically recommend? I spoke with a local well guy around here (Virginia Beach, VA) and based off pics I texted him, he said I had a deep well pump. It has two pipes for the inlet and one for the outlet. Again, its a Grundfos JP-7, product number 46900021. He also said he'd recommend ditching the large expansion tank and putting a much smaller one on there. The model he recommended was a Sta-Rite SLE-L but like I said, I'd prefer to invest as little as possible into this repair. His turn-key cost to handle everything was $1,350.

I've inserted pics of my setup. It's not pretty but it works. This pushes my irrigation system and two outside faucets.

And what is TC?

20240523_133737 (2).jpg

20240523_133716 (1).jpg
20240523_134046 (1).jpg
 

jobondur

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Much appreciated @Valveman When I watched the video linked to that well pump it says if you don't replace the pump you have with the same exact pump you need to replace the jet package in the well to ensure it matches the new pump. I have no intent to mess with the well itself. Do I need to do anything more than cut out the old pump and plumb in the new pump?
 

jobondur

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Also, am I going to have any issues going from a 3/4 hp pump to a 1 hp pump?
 

jobondur

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So I pulled the pump apart again and think I may have figured out the problem. I think I am using the wrong shaft seal. When I install the one I have it's not physically possible to compress the spring enough that the rubber gasket on the spring section can actually seat and seal around the shaft. It looks like the part with the white ceramic face is too thick and sticking out too far. How do I find the proper shaft seal part number for this pump? I contacted Grundfos and they sent me THIS link but I can't seem to find it in stock anywhere.
 
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