Can a Scorched, Grooved Impeller Ring Cause Pump Surge?

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happyheathen

happyheathen

0
Aug 18, 2012
224
Sacramento CA
Hayward Northstar 1.5 HP.

Started to shock, left pump running overnight. We'll call them needles, but these are much finer; had matted the area around the intake on the pump basket. This was probably a water-proof patch about 3x4 inches.
The pump was causing waves.
Turning it off and cleaning the basket produced a surge action on trying to prime.

I have it open - no needles or other obstructions. Motor turns freely.

The white plastic part ID'd in the manual as SPX0321R Impeller Ring (the guy in the dis-assembly video I found refereed to it as "wear ring") shows a scorch ring and about 20 small rotational grooves on the inside.

Before removing the impeller and risking damage to it:

Is it possible that the damage to the ring could be all there is to the problem?

Having no way to test short of re-assembly and installation, I'd like some idea of probability of finding the problem before buttoning it back up.

Beyond this. only the shaft seal is replaceable.

The obvious thing is to buy the impeller kit and throw it at it - but my back still hasn't forgiven me for pulling the motor...

thanks as always
 
I have two XP3 filstars and both of them have experienced damage to the magnet that surrounds the impeller. The grooving causes the unit to be quite loud. When it happened to my first one, I used the magnet out of my spare unit. It worked fine for a couple months, then the noise started. I checked it and the magnet was damaged on that unit also. It basically has rounded grooves up and down it. I've had the first unit for about a year, the second one for about 9 months. They both work fine, they're just very noisy. I don't want to purchase replacement magnets if they're only going to last a few months.
A: Heat causes this and you can find many Q&A's rgarding heat and motor damage on the site. Since the item is under warranty you might want to contact the manufacturer, Mars Fishcare about the problem.
 
Explain more about the surge action?
Is it constantly surging when it's running or just when priming after cleaning the basket?
When you say "surging", is it the water surging in the pump basket or is the motor surging?
 
The motor sounds normal; it fails to prime after a minute or two of rising and falling water levels in the basket - at the best, the amount of air is problematic; at low point I would be scared to allow it to run any longer.

I've had near-constant problems with (second-hand) pumps - I had this on unions to eliminated possible stress to avoid alignment problems causing leaks. I doubt that it was a leak develop after running fine for 5 hours.

If it was the motor making unusual surging noises, I'd believe the youong man at Leslies who assured me it was always the motor having a fried winding which caused water surging in pump baskets. but I don't see how a fried winding could cause variation in pump capacity.

thanks
 
Well, the skimmer has no weir, and water level did not drop 2" in time it ran - I've had the pump sucking the skimmer dry in the past - I make sure there is at least 2" standing with pump off.

Again, this occurred during initial shock (I had drained it to get rid of mustard algae) - this was a brand new fill on a system which (finally) was running fine last summer.

Wat I'm hearing is that it is indeed most likely the motor.

We have:
Known good system
Initial fill to 2" of water above skimmer inlet
Overnight run begun early evening
Super dense pack of V-shaped thistle seeds ("needles" is easier to type and comprehend) plugging pump basket
With basket cleaned, sump re-filled and pump start:
Water begins to rise, the filter bleed valve is expelling air and water.
Once the water just reaches the basket cover lens, it drops to just above the top of the (impeller inlet, sump outlet), then rises as before.
Repeat until bored.

Remove pump; pull motor
Only visible "not right" are the marks on the impeller ring; impeller has a single spec of vegetation about 1/4" long, otherwise spotless.
All left is to pull the impeller and check the shaft seal.

That's it in a nutshell

again, thanks
 
Two things:
1. the impeller has grooves on its nose, corresponding to the grooves on the impeller ring. Surprise, right?
2. How much torque should it take to rotate the impeller by hand - I can't come close to getting it to spin as I can with the bench grinder motor, but it doesn't need a seal capable of withstanding water at 20 psi, either.
A seven year old could turn this; a kindergartener probably couldn't - could the bearings be binding?

(I checked - all 4 through-chassis bolts are free, if I need to open the motor)

Which direction - cw or ccw does the impeller need to be turned to remove? And what do you use for a wrench, assuming you don't have the highly specialized tool sold for this exact use sitting around?
 
The problem is not related to the motor.
The problem is flow to the pump. You either have an air leak on the suction of the pump or you have a restriction somewhere in the suction line.
Have you tried running water from the pump back to the skimmer?
 

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Also, 2" may not be enough in the skimmer. It could be creating a vortex which is sucking in air. With the pump on, go look at the skimmer and see if it is sucking air.
 
I'll dig out the drain king and check the suction line backwards.
Based on earlier disaster, will pull the filter cart entirely

Is it not worth the time to check the shaft seal?

If I pulled this thing apart for no gain, I'm going to (again, surprise!) be annoyed with myself
 
Shaft seal would not cause that problem because it is on the pressure side of the pump. What you are seeing is an inrush of air so you just need to find out where it is coming from. If the skimmer creates a vortex, it can easily pull in air and it will oscillate in waves like you are seeing.
 
I (all too well) understand the problem of a too-low skimmer level - this thing is way over-powered (had a roof-mount solar heat system to deal with originally) and I've seen that up close and personal.
The drain king came up slit top to bottom, but the water was running freely from pump location to skimmer without ever coughing up any blockage. Don't know if it managed to find something to slice it or if it blew out trying to build enough pressure.
Will get a real Drain King (or at least a much more robust one than this one) and try again.
Will spend tonight re-assembling the pump.
 
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