First of all, I have to say that I am a beginner, so please excuse inaccuracies. I'll try to describe as much as possible, so you can get a better sense of the situation.

I have a shallow well to get water for gardening. The pump is a Wayne (General Motors) 5KH39HN3550BX21 1/2HP shallow well jet pump (SWS50, I believe), attached to a Wayne 59502-WYN1 bladder tank.

Every year, after winter, I prime it and get it going, but I have always been a bit bothered that the upper shut off limit was a bit low (60 psi), so this year I decided to tighten the nut to rise it.

No matter how much I turned it, it seemed that the limit was always the same, so I tightened it really a lot, and the limit seemed to go up a bit, probably around 63, but it would take forever to reach it.

I didn't do anything with the pressure of the water tank, which I suspect is on the lower side, although I have always wondered if that has anything to do with it. Also, there should be plenty of water in the well, as a low part of my garden was flooded just a few weeks ago.

Yesterday, I started the pump, and wanted it to go to the upper limit before starting to use the water, but then I went away to do other stuff, so I didn't monitor what was happening. I got back 25 minutes later, and the pump was still running (didn't reach the limit), and was very hot, but I could still touch it with my hand for a few seconds before it would get too intense. There were no water leaks around the pump.

I turned it off and let it cool down.

I decided to remove the cap of the main well pipe and re-apply Teflon tape, to make sure it was properly sealed, and did the same on the plastic fitting connecting the pump to the hose that goes to the tank, as I thought the high temperature might have warped the plastic.

Then, I primed the pump again, and after a few attempts, playing with the fill tap (I am not sure how to call it, but it is where I attach the hose with water from the mains to put water in the pump when priming it), and the tap of the garden hose. In other words, the taps of the priming intake, and the tap of the output. I am not sure if this is the right approach, but this is how I've always done it.

To my relief, the pressure went up again, and after a few attempts, I started to feel water was being drawn from the well pipe, making it become cool, which is the usual sign that the well is working. Anyhow, the overall pressure of the system seemed a bit lower than usual, probably around 50psi.

Unfortunately, despite the fact that the well was somehow working, I soon noticed that the pump wouldn't be able to keep the water output high enough unless I opened the tap very little. Opening the tap too much, would bring the pressure down to zero. I watered plants a bit, although extremely slowly, and when done, I brought the pressure up again as much as possible, I think around 50 psi, and then turned the pump off for the day.

This morning I went to check it, and the pressure was again to zero, but when I started the pump, the pressure went up a bit, to around 20psi, but without drawing water from the well pipe.

Before trying to prime it again, I figured I'd ask experts here first:

  1. Do you think the jet pump got ruined by the heat? And if so, what component? And would it be replaceable?
  2. Do you think that the pressure of the tank has any relation to the situation? I never fully understood how the bladder comes into play in the entire process, if not only to keep the pressure steady.
  3. Do you think that there might be a leak somewhere in the piping? Or is it more likely to come from the pump?

I'm ready to disconnect and reconnect all the piping, but I would rather avoid it, if possible.

  • Some pumps do have a maximum remember that a jet works on a Venturi it is not a pump designed for high pressure. If it was cool enough you could touch the seals are probably worn so moving the pressure down to a point it can make could give some more years of service but keeping a high cut out pressure will probably do it in wile raising your power bill.
    – Ed Beal
    May 14, 2022 at 16:18
  • Thank you. I'll lower the pressure point as you suggest. But I was wondering why the pressure drops completely after some hours. Could the system lose pressure from the pump (as opposed to the fittings)? Also, just in case, is it possible to replace the seals? I wouldn't mind trying if they are not too expensive and it is not too complicated.
    – user151717
    May 14, 2022 at 18:39
  • You don't give your model number, but if you add your model number to Wayne 1/2 hp shallow well pump rebuild kit in your search engine of choice, you should be on your way to fixing your worn-out, somewhat abused recently, pump. Also, if 60 PSI isn't more than adequate to water your garden, you have got to be doing something wrong. A 40/20 or 50/30 setting should be just fine for that. In any case, you need to correctly adjust the bladder tank pre-pressure for the setting you are using.
    – Ecnerwal
    May 14, 2022 at 21:18
  • As Ecnerwal says yes they can be rebuilt if you can find the correct parts the pump can be rebuilt, some think this advanced but with the internet and modern instructions I would say intermediate skills to end up with a like new pump after a rebuild.
    – Ed Beal
    May 14, 2022 at 21:47
  • I'm not saying it happened here, but some water pumps require water to be flowing through them to cool the parts. Without cool water, plastic and rubber parts melt.
    – RetiredATC
    May 14, 2022 at 21:49

1 Answer 1


Pump rebuild kit from supplyhouse.com - no endorsement implied

New impeller, new seals, new life for tired pumps. An example (no endorsement implied) of a rebuild kit, which are commonly available.

To avoid making your rebuilt pump old again in a hurry, stick to a maximum pressure that the rebuilt pump can easily reach. If you set pressure above the pressure the pump can produce, it will just run and never stop, as you already discovered. Without fresh cold water moving though, it will overheat, as you've seen. Overheating is not good for plastic pump parts.

If you'd like to have absurdly high pressure available and no need to prime the pump, swap it for a 1/2 hp (or 1/3 hp, but those are less common) submersible pump down the well. You'll have to be careful about the maximum pressure of various system parts that commonly top out at 100 or 125 PSI - but if you find higher rated parts, you can water your carrots with 150PSI or more if that really makes your day...my carrots seem to be perfectly happy with 10-25 PSI on the hose.


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