Main Sewer Check Valve

[Jeff Handy]

The original problem that you described, which is that only a huge flush of water can lift open the flap for the valve, will not be helped or improved by cleaning up the flap or the sealing face it rests on.

Meanwhile, you should put some penetrating oil all over the bolt that holds the flap on.
That should help the flap to swing up easier.
Then manually operate the flapper many times, to work in the oil and to grind up any crud stuck inside the hinge.

I would not remove that bolt, it looks stainless which is brittle, if you go squeezing that split end and then re-spread it, it might snap off at the splits.

 

[Jeff Handy]

Meanwhile, post some better pics of the whole valve, showing a much wider and clearer view.

It might be time for a new and better backwater valve to be set into the floor.

One that opens easier to allow sewage and solids to pass, and to self-clean itself.

If yours lets junk sit trapped on the flapper seal, it might not stop a sewer backup from running right into your basement.

 

[CT18]

Or take a dremel and cut that screw off and remove the flapper

 

[Geofd]

Is there room to replace???????