Grundfos pump motor hums

Do you mean a circulating pump for hot water heating?????

Thee is a screw on the back of the motor. Remove it and inside you can see the shaft. With a small screwdriver, you can turn the shaft a bit. This can be done with power on or off. If the power is on, it may start to turn slightly and then pick up speed. When mine were getting old, I had to do that at the start for heating season, they they were good for the year.

When one of the pumps finally did go I replaced it with a Taco. It was just not as quiet, but it did pump water just fine at half the price.

This pumps water through solar panels. I tried turning the shaft. Frozen solid [after only 3 years]. Guess the bearing is gone. Not impressed with the price/quality. I'll look into a Taco. Thank you.

Sounds right , modern quality, old unit works 30 years, new unit works

I wish as these cost @ $200. You'd think there might even be kits available. But I tried replacing the bearing with the last one and I'd say Grundfos really didn't make these bearings "user serviceable."

As to your original post, check the amp draw. That's totally valuable information.

Hope you can dissemble the pump, clean it up, and make it last for a few more years. Some electric water pumps (Bell and Gossett comes to mind) have oil holes to drip in some ND20 oil.

Cause it doesn't know the words.

We now return to your regularly scheduled posts.

I've search but not found Grundfos parts and assumed I'd have to buy a new pump. I was pleasantly surprised that the local Grundfos dealer encouraged me to bring the pump in for a free disassembly. Pump had overheated [showing brown build up in interanls] but bearing was good. Dealer installed a new rotor/impeller assembly and unit seems good as new. $25. I was shocked by the high level of service.

Always nice to hear a happy ending. Any idea what caused the buildup? Was it gunk in the system?

No idea. The water here in Hawaii is soft - rain water filtered through lava dikes. My pipes are 30 year old copper but I never see crud in any of the faucets. The brown residue was very thin, just enough to upset the tolerances of the low hp motor.

Inexpensive, good quality service? That's rather rare, and good to find.