[terpda_49]

I boil 5 gallon batches in a 10 gallon stainless steel Kettle.  Wort cooling is with a copper coil immersion cooler and I have a separate 1/2" copper tube with outlets to circulate the wort when cooling.  Use a Chugger Classic Homebrewing pump with polysulfone head.  I place the cooling coil and recirculating pipe into the boil about 20 minutes prior to flame-out.  Pump is placed about a foot below the bottom of kettle with the outlet port pointing "up".  Use 1/2" brass fittings and 1/2" ID Silicone tubing.  Inlet to pump is from the kettle drain valve.  Pump outlet the tubing goes to the top of the kettle and connects to the circulating tube.

I make sure the pump is primed and there is wort all the way up the return tube before starting the pump.  After 10 minutes the wort stops moving through the tubing.  The pump runs, but no wort is pumped.  Made sure there was no air in the pump, tried throttling down the outlet from the pump, and even let the pump rest for a while, but nothing seems to get the wort moving again.

I disassembled the pump head to make sure the rotor was free.  Everything looks fine.
When this has happened in the past, the pump would later work fine for circulating my cleaning solution, but yesterday it wouldn't even do that.

I'm looking for any suggestions on what I may be doing wrong.  Why does the pump work for a few minutes and then stop moving liquid?

[a10t2]

There are two designs for March pump heads and I don't know offhand which one Chugger copied. In one design the outlet goes straight out of the head and in the other it makes a right-angle turn just after exiting. If you have the latter then the actual tubing should be horizontal for both inlet and outlet.

It could also just be an issue of trying to pump near-boiling wort, which impeller pumps are really bad at.

[denny]

Sounds like your pump is cavitating.  Fairly normal for boiling wort.  Mine works better in that situation if I reduce the output.

[smkranz]

Look to see if there's a little nylon "thrust washer" on the impeller shaft just under the impeller.

[RC]

My Chugger does exactly the same thing every so often. It drives me nuts. In my case, the pump makes a sudden "clunk" sound, and the whirring noise changes to a higher pitch. It stops pumping after this. I turn it off, let it sit for ~10 seconds, then turn it back on. Usually, it goes back to pumping just fine for the rest of the brew session. It's not cavitation--that makes a different sound, plus this happens even with cool liquid and plenty of head on the suction side. It might be that air has somehow gotten into the pump head and I just don't know it, (nor can I figure out how the air got in). I've taken the head apart but nothing anomalous inside. I have absolutely no idea what it is. I chalk it up to some design quirk that rears its ugly head once in a while.

That said, perhaps your return stream has bubbles in it, and it's returning the wort close to the kettle-valve outlet, so the bubbles are getting sucked back into the loop.

[soymateofeo]

I have the same problem.  I contacted chugger via email to ask about it and I have not heard back from them after 11 days. I have read on some forums about weak magnets and bad impellers.  Chugger customer service sucks.  Next time I will buy Blichmann.

[jjflash]

I have used a couple Chugger pumps in my set up for years.
I initially installer the center inlet style thinking how great it would be to have direct flow.
Son of a gun would constantly cavitate and no flow.
Chugger exchange me for the side inlet design and have had no cavitation issues since.

[Kirk]

I boil 5 gallon batches in a 10 gallon stainless steel Kettle.  Wort cooling is with a copper coil immersion cooler and I have a separate 1/2" copper tube with outlets to circulate the wort when cooling.  Use a Chugger Classic Homebrewing pump with polysulfone head.  I place the cooling coil and recirculating pipe into the boil about 20 minutes prior to flame-out.  Pump is placed about a foot below the bottom of kettle with the outlet port pointing "up".  Use 1/2" brass fittings and 1/2" ID Silicone tubing.  Inlet to pump is from the kettle drain valve.  Pump outlet the tubing goes to the top of the kettle and connects to the circulating tube.

I make sure the pump is primed and there is wort all the way up the return tube before starting the pump.  After 10 minutes the wort stops moving through the tubing.  The pump runs, but no wort is pumped.  Made sure there was no air in the pump, tried throttling down the outlet from the pump, and even let the pump rest for a while, but nothing seems to get the wort moving again.

I disassembled the pump head to make sure the rotor was free.  Everything looks fine.
When this has happened in the past, the pump would later work fine for circulating my cleaning solution, but yesterday it wouldn't even do that.

I'm looking for any suggestions on what I may be doing wrong.  Why does the pump work for a few minutes and then stop moving liquid?

Is the magnetic cup (motor side) loose from the shaft? What about the two washers inside the pump head? They seat the propeller properly in the head...It could be losing coupling if the gap between the propeller magnet and the magnetic cup are too far away from each other.

[soymateofeo]

I recontacted chugger and I got back this video in reply.  he suggested the pump ran dry or has crusty wort built up.  I will check the inside of my impeller more thoroughly.  https://youtu.be/Hd-Dx84fjFU

[Chino Brews]

This may be the answer you need:
https://www.exchilerator.com/chugger-pump-noise-fix/