Pump cavitation issues

[Schwerkraftbrauer]

So I have' a used chugger pump with the stainless steel inline head with 2 valve operation configuration with the out Port facing up(one bleeder, one flow control) .

It seems like I'm constantly battling cavitation and pressure loss. Mostly with liquids that are hotter than 170 degrees to Boiling. I bleed the valves out and all the air pockets to only have it cavitate within 2 seconds of the pump on. I do not open the valves fully this problem happens even if the valve is just cracked slightly and I never start the pump with valves open. I feel like I've tried to troubleshoot everything that I possibly can with this pump and wondering if I need to upgrade to a different one to not have this issue. Very frustrating trying to hold temp and transfer liquids. And I feel like I've tried virtually everything to correct this problem,

Any ideas from the peanut gallery?

[czubak]

Why do you have a bleeder valve? What is "2 valve operation mean?

My method is open the out valve of the kettle and open the out valve off the output of my pump. Liquid fills the pump head and I hit the power for the pump. Easy peasy

[Schwerkraftbrauer]

Just was the setup it had when I bought it

After the pump has a T and one valve for a bleeder and the other valve going to your destined vessel

[czubak]

IMHO remove that air bleeder.

[Matt F]

I use to have a bleeder valve like your setup. I did not use it often but did not hurt anything. I try to make sure I get all the air out of my lines before I start my pump. For my setup I would take the hose after the pump and lower until gravity pushed all the liquid through so I knew the hoses had all the air removed. Basically drop the end of the hose to a low enough point until liquid pushing out. If not the air in the lines would collect in the pump head over time.

[tony b]

My best guess is an air leak. Check your hose connections when the system is hot.

[Schwerkraftbrauer]

Good to know every once in awhile on a chugger pump you need to take a 17/64 drill bit and reem the hole inside the propeller. My pump seized today while doing a batch in a couple quick searches on YouTube found that it when it runs dry(sluggish) you need to do this every once in awhile.

Pump runs better now than when I got it last year. Just thought I would tell people in case you need to add this to the cleaning regimen I know I will

[daryl]

How could you tell when the pump was seizing?

[Schwerkraftbrauer]

How could you tell when the pump was seizing?

It quit pumping wort and the propeller on the back end that cools the motor quit as well. Made a low pitch grinding noise also

[daryl]

I have had that problem too; and had similar experiences as you. I haven't had any issues with it in quite some time, and here is what I think is happening.

I think the housing of the pump and the magnetic cup (which is magnetically coupled to the impeller) have become slightly mis-aligned. It works on the bench, but once it gets heated up, the rotor seizes because the housing and the spinning magnetic cup have made contact.

I took mine apart and ran the motor without the pump housing, to make sure the magnetic cup spins without a wobble. I then made sure the inside of the cup was clean....and then when I put the housing back on, I made sure the house was properly aligned in the center (or what I perceived as center, because you cannot see the cup when the housing is on). There is a tiny bit of play...and if it gets off center, the housing could touch the cup.

I think this might be what is happening, as I do not believe the magnets they use to couple the spinning cup and impeller would be strong enough to stop the motor from turning.

I might take one of my pumps apart, place the housing back on without the impeller cover, put the impeller on the shaft and hold it in place (with a towel?), and then run the motor to see if the motor turns when the impeller is locked.

Thoughts?

[Schwerkraftbrauer]

The video I found from the company chugger pumps on YouTube shows that you should be able to flick the propeller with your finger and have it free Spin if it's not doing that it's clogged up and you will have to bore it out with a bit. All I had was a quarter inch drill bit held the drill in one hand propeller in the other and just slowly moved it back and forth with the drill on high. Placing the propeller back onto the shaft it would free Spin like the one in the video did.

It's also worth noting I can now run my pump with the out valve fully open where I couldn't before. I'm amazed it made my pump like new again

[Schwerkraftbrauer]

https://youtu.be/Hd-Dx84fjFU

[daryl]

He is talking about debris in the impeller bearing causing the impeller to seize. At about 13 seconds, he says "...the motor will decouple and you will get no movement...". I think what he is describing, is that there would not be any movement of the wort, and that the motor is still rotating (but decoupled from pump housing).

But I'll check it out when I try to run the motor when I have the impeller locked.

If it does run, then if the motor is seizing and still drawing current it has to be due to: 1) The pump housing is touching the magnet cup drive so the motor does not turn...or 2) The bearings or brushes (if the motor has them) in the motor are going bad.

I'm not sure about scoring up the inside of the impeller bearing with a drill bit. I did do a serious cleaning once, with Q-tips and a strong PBW solution and then again with rubbing alcohol...and I was able to get clean so that the impeller spun very freely....but the motor would still seize.

I'll see if I can experiment with my pumps tonight and I let you know what I find out. And...I can check one out for you.