Strange noise from sump pump, when OFF

[wetguy]

Hi - I live in New York and we're having a crazy storm now, with flooding everywhere. I noticed a bad sound coming from my sump pump. Video below. The crazy thing, is that this is the sound that is coming out of it when OFF. In other words, when the pump kicks in, the noise stops. When the pump stops running, the noise starts up.

The thing that really has me perplexed is that this noise continues even if I unplug the pump. I assume this is not a good noise, but does this mean failure could be imminent? What could be causing this noise and why does it continue even after unplugging the pump? Needless to say I am going to have it looked at asap, but I'm curious what this is and how bad it could be. Thanks.

 

[RS]

Where does the pump discharge to? It sounds like water running back down the pipe into the sump, if there is a check valve it's possibly not working properly. With all the rain the discharge area might be flooded and water is siphoning back.

 

[wetguy]

Hi - I don't think this system was really well thought out (was there before I bought the house). It looks like the pump was intended to drain into a line that leads to a dry well in the yard. But in moderately heavy rain, the dry well fills up and water backs up. When the pump runs, water just gurgles out of the pipe and then sits on the side of the house. It's not a good setup at all and I'm sure is putting way too much strain on the pump. I have never heard this knocking noise before though.

https://youtu.be/Geimk5ujNCg

 

[RS]

It looks like you should make a temporary change right away to get the water away from the house, and then make a long term improvement when it dries up. If the water is siphoning back then you are just pumping the same water over and over

 

[House Doc]

I'm originally from outside Chicago and have dealt with sump pumps for years (no basements in Calif)
1st It sounds like a bad check valve.
2nd Dry wells are OK for occasional rain but they need time to drain themselves. As it is the water is draining right back into the sump since the "dry well" is full (Not good for the foundation). I would modify the exit pipe so it could be routed to a flex hose to drain away from the house during times of heavy rain. Use a couple of Fernco connectors to make it easy to change back and forth using the drywell when rain is light.

 

[wetguy]

Thanks - yeah I had wanted to set up something like you describe years ago, but never pulled the trigger. I know my town has some strict rules about where the water can go - but if not drywell, I don't know where else it could drain. I just took a plastic tube I had and manually siphoned out the water that was sitting there. The entire wet area around it dried out when I did that. This means literally the same water is just being recycled over and through this system which is ridiculously inefficient. Will have to figure out a better long term solution. I still want to understand physically what is causing this knocking sound. It sounds mechanical, but I know it's something physical.

 

[Jeff Handy]

As has been said, It is likely a bad check valve, which is supposed to be a one-way flapper type valve, but yours is letting water slowly chug backwards.

However , I don’t see one there.

So it might be buried in the wall, or down in the pit, or somewhere else on the discharge line.

The saturated dry well might be causing back pressure which has damaged the check valve.

You can cut the discharge in the basement, and adapt onto a flexible sump pump discharge hose, and temporarily run that hose out a window into a better area of sloping drainage away from the house.

These hoses are cheap vinyl and can leak or burst, so not safe for indoors long term.

It would be safer if you could tie that flex hose into the discharge somewhere outside.