How to Get Threaded Shaft Out of Pump Impeller?

[SteveHGraham]

I got my sprinkler pump out of the shed. Now I have to get the motor off of it.

I can get the remaining bolts out, but the shaft is threaded into the pump's impeller, so I need to unscrew it. Is there a trick to this? I can access the shaft to turn it if I succeed in destroying the motor housing, but I would need some way to immobilize the impeller.

The previous installation is a wonder to behold. It took me a long time to cut the PVC pipes with a Fein tool, and now I know why. Someone put layer over layer of plastic in the inlet pipe, and the opening is maybe 1.25" instead of the minimum required 1.5". The walls are 3/4" thick. It's also irregular and full of bulges and globs. Nice.

The motor wasn't grounded, so that's another thing to be joyful about.

The hex screws that held the cap on the motor were somewhere between 1/4" and the next smallest size (including metric), so I had to remove them with Vise Grips. A 1/4" socket slipped, and the next smallest one wouldn't go on.

[BadDog]

Sounds like ours is different. On my pool pump, IIRC, I had to remove the end bell of the motor to access the flats on the rear of the shaft. Then, with the impeller housing split, turned the impeller to screw it off the shaft. Seems like I recall there being a clip or something in there, but my memory isn't clear. Lots of stuff like that I do it "on automatic" and move on, often without remembering having done it. If it doesn't give problems that make me focus and think, it doesn't stick in my memory.

[GlennW]

Like Russ said, remove the end cover from the motor and look for flats on the shaft somewhere. Mine were A.O. Smith and you needed to remove the centrifugal starter assembly to get a wrench on them if I remember correctly. Definitely had to remove something to gain access to them.

You should be able to hold the impeller with one hand and unscrew it while holding the wrench against the bench with the other. Size 13 hands here though...

[SteveHGraham]

Here is the problem (the latest). The pump will not come apart. I don't know if it's rust or what. The bolts that hold the halves together came right out. I had been hoping there was some clever way to immobilize the impeller with the pump still assembled, but I guess that was a pipe dream.

I took the tub off my shop vac, added a soda solution, put the pump in, and hooked the pump up to the battery charger. Maybe the crud will come off to the point where I can get it apart.

I took the motor off in pieces. It was not in good shape at all. Now it's just a shaft, a bearing, and a rotor.

[SteveHGraham]

My new concern is that the motor I ordered will arrive AFTER I discover that the pump is hopeless.

[SteveHGraham]

I may throw this thing in the trash, cancel the motor, and get a new pump. This is too much aggravation.

[GlennW]

That's why the sprinkler guys make the big bucks...

[SteveHGraham]

I'm getting a new pump. I had no business listening to the incompetents who came out here. I should have researched more. They gave me the impression that a new pump was a big expense, and I didn't check. I only looked at motors.

The motor is $165. A rebuild kit is $115. A new Goulds pump with a motor is a little over $300. The choice is obvious.

Hopefully the motor I ordered hasn't shipped yet. If it has, I'll just pay whatever I have to to send it back.

I can't trust anyone down here to do this simple job, so I'm going to have to make an aluminum base and do the wiring and plumbing. Unbelievable. The last guy didn't ground the motor. How stupid can a person be and still breathe?

I finally made out some of the lettering on the motor that died. It's Mexican! No brand name. It's 2 HP, which is 0.5 HP more than it should be. So I was paying for useless horsepower to pump water through a pipe that was too small. Of course, once your flow is restricted past a certain point, all the horsepower in the world won't help.

The motor was completely trashed. Every part that could corrode was messed up. The only parts that looked okay were a capacitor and the centrifugal switch.

[liveaboard]

I repaired mine; 1.5hp was damaged by running dry.
I had to weld a lever onto each case bolt to get them out.
Destroyed the impeller getting it off, but it was junk anyway.
I put the armature in a vice and used big Facom locking pliers.

New impeller and seal, and it's been working since.

But I still have no way to stop it from running dry again. I have to pull water up a tube out of the irrigation canal, I'm not allowed to put anything electrical in the water. Sometimes the level drops or they drain it completely for maintenance.

I was looking for a relay that would cut the motor if the current went too low for a minute, but didn't find one here.
I was thinking of making a little chamber that would be attached to the suction tube, that would house a micro-float switch. I'd have to add a timer relay or maybe 2 relays.
Complicated and expensive.
I asked at a pump specialist; I'm amazed there is no off the shelf electrical gizmo to do this simple job.

Next year my place is supposed to get pressurized irrigation water, so I don't want to spend too much on the pump now.
They haven't told us how much that water will cost, so I don't know if it will be useful to me or not.

[SteveHGraham]

Did you consider Rule bilge pump switches? Rule is a brand name. They turn on when the water reaches a certain height, and they turn off when it goes down. The on and off levels are different so they don't cycle constantly.

You would have to make sure you have it fixed up so you don't fry it. They're made for low-voltage DC, obviously. I'm sure there are other float switches out there. Maybe Mouser would have them.

While I was looking for help on the web, I found a test of six irrigation pumps, and the Goulds GT15 was best at self-priming. Guess which model I just bought! Sounds like it might be a good choice for you.

http://www.walmart.com/ip/33276858?wmls ... 51&veh=sem

[BadDog]

Assuming a pressurized system as opposed to one just running open (such as to transfer water to from one res/canal to another), how about a simple pressure switch? If the pressure drops below your set expected minimum, you either have a busted pipe, or it sucked air, either way it turns the pump off till reset.

[Russ Hanscom]

Use a float on a long arm that activates a micro switch - nothing electrical in the water.