New Century V-Green Motor: stuck, won't start without help

[gms]

Hi Folks,

I've dropped in a retrofit Century variable speed motor (EVO 2.25hp) to replace a 13yr+ old single speed motor on my Sta-Rite pump. The kit included a new impeller, diffuser, seal. The problem I've been seeing is the pump won't start by itself unless an Allen key is first inserted in the back of the motor and the shaft rotated slightly. (The shaft itself does rotate freely btw). This has happened to the "first" new pump as well as its warranty replacement...

I rechecked the mains connections and took some current measurements with a clamp on AC ammeter: Clean 120v L/G, 240V L1/L2, doesn't droop at all on start. When it attempts to start, the unit draws 270mA for 5s or so, then (a relay or something) clicks softly and the current drops to 250mA. This cycle continues for some minutes before it times out and the LED control button flashes 4 times to indicate a seized shaft. If I power off, rotate the shaft slightly, then power on, the unit will soft start up to full prime speed, with the current draw eventually reaching 6.8A. It'll run all day once started, then be stuck the next morning.

Seems as though the unit's "soft start" is so low torque that it can't overcome the token startup friction between the impeller and diffuser (which came matched in this kit btw). Does anyone have background on whether such small startup current measurements are typical or a sign of a defective unit? Anybody experience something similar?

Thanks in advance for any advice here!

 

[MSchutzer]

I think I would disconnect the motor from the pump's wet end and see if the motor starts okay by itself. If it starts okay when disconnected then there may be something dragging when installed in the pump. A normal pump seal / impeller installation should add negligible resistance to the motor spinning when its just starting.

 

[ajw22]

Let's see what @1poolman1 thinks. I think he as installed a few of them.

 

[1poolman1]

Let's see what @1poolman1 thinks s he has installed a few of them.

I think you have a lemon and should make a warranty claim.

I've not installed a new EVO yet. If you have had two motors with the same issue, I would look elsewhere for the problem. What pump is this, a Max-E-II? Those pumps were very susceptible to tiny particles getting between the impeller and diffuser and causing what you are experiencing, especially in the 1.5 - 2hp range pumps. Never saw it on a .5 - 1hp.
If the motor starts with no issue when the pump is disassembled (diffuser off), I would, on occasion, take a bit of fine sandpaper and, with the motor spinning the impeller (high speed), lightly sand the "nose" of the impeller to clear any rough areas. You have to be quick as the seal will be running dry. About 10 seconds is all it ever took and won't damage the seal. Helped most of the time. You can also lightly sand the bronze ring in the diffuser.
Haven't heard of any issues with those motors (yet?).

 

[gms]

I've not installed a new EVO yet. If you have had two motors with the same issue, I would look elsewhere for the problem. What pump is this, a Max-E-II? Those pumps were very susceptible to tiny particles getting between the impeller and diffuser and causing what you are experiencing, especially in the 1.5 - 2hp range pumps. Never saw it on a .5 - 1hp.
If the motor starts with no issue when the pump is disassembled (diffuser off), I would, on occasion, take a bit of fine sandpaper and, with the motor spinning the impeller (high speed), lightly sand the "nose" of the impeller to clear any rough areas. You have to be quick as the seal will be running dry. About 10 seconds is all it ever took and won't damage the seal. Helped most of the time. You can also lightly sand the bronze ring in the diffuser.
Haven't heard of any issues with those motors (yet?).

Yep, Max-E-GlasII it is
Thanks, I'll split the pump and give this a try... When spinning the motor/pump with an Allen wrench, although it does spin freely, I do feel about 90deg of somewhat more resistance. I'm just surprised a new pump wouldn't be able to break that free (equiv to two fingers light pressure on the small end of the Allen wrench?) My old single speed induction motor I'm sure was way more torquey.

 

[Poolbreh]

Make sure the motor is flush with seal plate if it’s off, the impeller will rub on the diffuser causing the issues you described.
The diffuser would show more wear on one side of the inside ring.

 

[1poolman1]

Yep, Max-E-GlasII it is
Thanks, I'll split the pump and give this a try... When spinning the motor/pump with an Allen wrench, although it does spin freely, I do feel about 90deg of somewhat more resistance. I'm just surprised a new pump wouldn't be able to break that free (equiv to two fingers light pressure on the small end of the Allen wrench?) My old single speed induction motor I'm sure was way more torquey.

Also, to add to Poolbreh, be sure the sealplate is completely vertical, the center line on the back is not off-center to one side or the other. That can cause the issue as well. Single-speed motors have instant torque, it has to build in a VSP. Even then, I first noticed the binding issue well before VSPs were available on those pumps.

 

[gms]

Also, to add to Poolbreh, be sure the sealplate is completely vertical, the center line on the back is not off-center to one side or the other. That can cause the issue as well. Single-speed motors have instant torque, it has to build in a VSP. Even then, I first noticed the binding issue well before VSPs were available on those pumps.

Will double check that... hard to see, but this pic I took awhile back shows the seal plate has this locater flange that mates up to the pump housing so if it's spun off center, it's not by much. I don't recall there being a lot of slop. The compression band on the housing pretty much rules out the motor and seal plate mating up off center (left right up down), plus the O-ring would probably leak even if that were the case?

Just remembered that the circled flange and the diffuser mate up (doesn't involve the pump housing). Will def. check alignment. Thanks...

 

[1poolman1]

Will double check that... hard to see, but this pic I took awhile back shows the seal plate has this locater flange that mates up to the pump housing so if it's spun off center, it's not by much. I don't recall there being a lot of slop. The compression band on the housing pretty much rules out the motor and seal plate mating up off center (left right up down), plus the O-ring would probably leak even if that were the case?

Just remembered that the circled flange and the diffuser mate up (doesn't involve the pump housing). Will def. check alignment. Thanks...

Diffuser O ring missing in the picture. Should be there. Also, does this pump have the copper heat sink in the sealplate. I've seen the wrong O ring used on those causing the seal to bind on the impeller shaft. They were no longer used after Pentair bought StaRite.

 

[gms]

Diffuser O ring missing in the picture. Should be there. Also, does this pump have the copper heat sink in the sealplate. I've seen the wrong O ring used on those causing the seal to bind on the impeller shaft. They were no longer used after Pentair bought StaRite.

Yep, Diffuser O-ring got lubed up and installed right before I mated to the pump, didn't want to have it accumulate any grit on the way to the pool pad.
No copper in the seal plate, I must have the newer model...
Great advice from you guys, looking forward to hopefully setting things straight Friday afternoon PST when I'm free (pesky day job!)

 

[gms]

@1poolman1 for the win... This impeller and diffuser set were a pretty tight fit, and the impeller itself had a little eccentric wobble to it that interfered slightly enough against the bronze diffuser ring to cause the pump start issues (see attached pic) These pumps really do have a feeble startup torque.

I cleaned up the wear on the bronze ring, ran the impeller without the diffuser and gave it a light sand as suggested. Pump started right up. I can't help being paranoid that I damaged the seal, so I'm going to swap that out next chance I get so I don't have to have that nagging feeling...

Thanks everyone for the advice, you got us back up and running!

 

[gms]

Going on a month now with no start issues. Looking good