HOT Motor

[Bnelson]

I just replaced the motor on my pump and it ran ok for a while (hrs) but then shut down due to overheating. It is VERY hot. Could fry an egg on it.

Does anyone know why the pump would over heat?

The old one was also hot to the touch when it was running.

[Poconos]

Motors do run hot but not enough to trip the thermal cutout. The only thing I can think of is a lack of proper ventilation. However, the fact this is a new motor kills that idea. An overload will cause a motor to overheat but with a centrifugal pump with a properly sized motor, this should not cause an overload situation. On any motor a shorted winding would be a quick overheat and smoke, not a slowly developing problem.
How about more details on what you replaced with what? Anything else change between the motor swap?
Al

[Bnelson]

I only replaced the motor. The original motor was an 1.5hp AO Smith BN35. The new one is a BN35SS. I also replaced the seals. Along with switching the power cord from old/new motor. It has cooled down now and I rechecked the tightness of the impeller. It was fine. Plugged it in and everything looks good except the motor makes a noise when it is running. Not quiet, sounds like something is loose on the shaft. Took the impeller off and ran the motor, same noise so I know it is not the impeller. I am going to see how long it runs before shutting down.

[Poconos]

The only thing that is on the rotor other than the impeller is the weight assembly for the centrifugal starter switch. If anything is broken there my guess is the motor wouldn't start. If it is bearing noise you hear I would think that unlikely too on a new motor. Assume the bearings are indeed bad and causing enough of a load to cause the motor to overheat, the bearings would fail in minutes because of the heat buildup. Only thing I can think to suggest is to run the motor without load and see what happens. You seem to be able to pull the motor easily so I'd do that, remove the impeller, and just run it for a while and see if it overheats. Bearings can get noisy but when they do they don't load the motor significantly until they are ready to burn up. When I used an IR thermomeyter on my 1 HP motor case I think I remember it running at 140 deg F so they do run hot. May seem like a stupid question but are you sure the thing is wired for the right voltage and 240 isn't actually being applied to a 120V configuration? Which is it supposed to be? Can't think of anything else at the moment. Anyone else with ideas?
Al

[Bnelson]

It only pushes 4.5psi after the filter. I wired it the same as the old motor. Running on a 20amp circuit. It does sound like loose bearings however. I will try running it today without the impeller on it to see how long it runs.
The pool store does not open until 11am, then I am bringing it back to them for an answer.

Thanks

[Bnelson]

My old motor was 110v/220v This new one is 115v/230v could that be the difference?

[Bnelson]

2 things. The motor only pushed 4.5psi because it was wired for 220, I hooked it up for 110. However, it was a defective motor, loose brushes or bearings. They replaced it with a better motor.

"Good things do come to those who wait."

[Poconos]

Glad the problem was resolved but it's odd for a new motor to have those problems. The 110/115 220/230 differences mean nothing and wouldn't cause a problem. FYI there are no brushes in these motors. Brushes are unsed in AC/DC motors such as found in shop-vacs, vacuum cleaners, blenders, electric drills and especially those devices where speed control is needed. Won't go into details as to why but when a motor wired for 240 is run on 120 it will slow down when under load. No load it will run almost at full speed.
Al