In July of 2004, I had a new immersible sump pump installed with hydromatic check valve. That's what the receipt says anyway!

From the beginning, the sump pump would make a loud banging noise after the sump pump ran and discharged the water to the outside. The day before yesterday, it just stopped making the banging noise. The pump seems to still be working. Is the pump getting ready to die? Does this mean the valve isn't working? Should I call a plumber?

It's getting to rain for the next 5-7 days here in Chicago and I'd like to call a plumber today to avoid weekend rates if I can. Hubby and I are NOT handy beyond the very, very basic.

Any and all advice would be appreciated.

The bang sound was probably the check valve closing againist the weight of the water trying to come back down your pipe. If the check valve was external on the stand pipe you can easily replace it yourself. It is held with two hose clamps that can be unscrewed, after that it is just friction holding it in. Many sumps have an internal check valve that can fail just as easily. Adding an external check valve would involve cutting the stand pipe and inserting the valve. Don't make the cut until you are 101% sure you have all of the parts and are ready to go. You will have no sump operation during the switch.

Thanks Ballenger! We wouldn't try to change it ourselves. It is an external check valve.

What I'm really wanting to know is whether the valve has failed because it is quiet now and do we have to replace it? Will the sump pump work efficiently/effectively without it?

The pump will run constantly w/out the check valve installed, which is never a good idea.