Possible pump motor bearing failure?

[mas985]

Again, does this only happen when the cleaner is attached and the suction ports restricted or does it also happen without the cleaner and with all suction ports wide open? This is a very important distinction.

If it is happening only with the cleaner attached, the cleaner hose maybe collapsing which is causing the oscillatory condition. Try removing the cleaner all together and open all suction ports and see if this continues to occur.

[kballard72]

The problem happens under normal usage. skimmers on, drain on, returns on.


The cleaner port is simply an example of one place I do have a gauge for. With a single 4 foot hose plugged to the port, and the flow gauge on the end, I can see that it is not drawing the suction it was say a month ago... But that is only to SEE what it is doing. The vac is not the issue...

[kballard72]

Diffuser came... having a point of reference, new versus old... it was clear the old one was worn. Where the wear ring butts up against the difuser used to be a ridge about 1/4" wide by 1/8" tall, not only was it gone but it was a valley on the diffuser.

SO, I thought viola, this is the problem we have been looking for... Replaced it... kicked on the pump all is wonderfully quiet as usual on start up.... basket fills up, all air purges... nice and clear window.... and 5-10 minutes later, so long pressure, hello irritatingly loud chatter....

thanks for all the insight, but it must be time for someone on-site I guess...

[mas985]

Unless you got that vacuum gauge.

BTW, does the flow rate out of the returns decrease or increase when the pressure drops?

[kballard72]

it definitely decreases. as well as the water feature, which is simply two returns on the sun deck that point straight up.. they drop from 2 feet high down to 6 inches....

For that wear ring to have carved away an 1/8" of plastic off the inside of the diffuser, is that a normal amount of wear?

Well clearly there were items worn out and they have all been redone, and seems to be casualty symptoms of something else going on. Impeller, wear ring, and now diffuser. All of which were visibly worn with the diffuser seeming to be abnormally chewed up. Either way all internal parts except the motor are shiny and new.

The odd thing is the split second change, as if something "gives" like suddenly the pressure is just gone... Its not gradual... after being off for awhile you can turn it on, all will be well, than bang, pressure dives and noise starts.

The noise which sounds like rocks clattering, is what I have read to be the sound of cavitation. So that may just be s symptom of the pressure drop and not the cause of it. One way I have found to make the noise stop is restrict the returns to cause the pressure to build up some. I dont leave it like that, just something I noticed.

[BigDave]

Is it possible that you have some flex PVC or other soft wall piping that may be collapsing under sufficient vacuum and time.

[kballard72]

No flexible piping in the system. Oh I wish it were the obvious solution. dry skimmer, etc.... covered already though....

[mas985]

The noise which sounds like rocks clattering, is what I have read to be the sound of cavitation. So that may just be s symptom of the pressure drop and not the cause of it. One way I have found to make the noise stop is restrict the returns to cause the pressure to build up some. I dont leave it like that, just something I noticed.

Those are the symptoms of cavitation and if a line is collapsing as Dave suggests or there is some sort of periodic blockage, increasing the return head would allow it to expand again (reduce the suction head). A suction gauge would help to confirm that.

Also, the video does not show the suction side plumbing very well. Do you have a check valve anywhere? Sometimes the flappers can break and cause similar symptoms.