Main Sewer Check Valve

Hello! I am new here and would love some help. I have a check valve on my main sewer line that’s attached to a reservoir with a sump pump. The flap for the check valve seems like it’s way too heavy and whenever there is a simple toilet flush, the toilet paper doesn’t make its way through the valve. There has to be a huge rush of water like from the washing machine or a full bathtub and then I see the flap open a little bit. Not even fully. I thought of taking off the cap to clean it and make sure there is no grime or sludge on it but it seems to be locked with a screw that’s secured by a nut and the ac res itself is bent outwards at the end so I can’t simply twist the nut off. Any thoughts or ideas here? Is this how they are supposed to work? How do I get the flap off for cleaning?

Can you show a picture of i??????????

Yes I’ll have to open it up tomorrow and snap some pics of the screw I’m talking about. Was hoping someone was already familiar with what I was saying. Thanks. I’ll get back tomorrow.

Take lots of pics, close and far, different angles.
Inside and out.

Can you see the pic with that screw for the cap?

Tough picture but it looks like an old backwater valve. You should be able to lift and clean the seal but the waste material has to work it’s way through. Hence the term “self-scouring” in the code book.

What do I clean the seal with? The waste gets stuck so many times in the opening. How can I take the cap off?

Can you manually lift the flap? If you can, prop it open and inspect it. And you could take the screw and nut apart and it should just come off. DONT LOOSE THE SCREW AND NUT!

Take a close look at the screw. It’s not a normal screw. I can’t get the nut past the part where it opens up

If you can lift it use a fitting brush on a drill and clean the surface were the flapper meets the fitting surface clean the edge
Clean the brass check surfaces clean the hinges then saturate them in penetrating olil cant tell but there must be a cover spray the threads and bolts after its working properly you gotta open clean and lubricate

But I can’t get the cover off. That’s my problem. Take a look at the pic and you can see this weird screw that’s ive never seen before. I can’t get the nut off the screw because of it

I zoomed in on that. It’s like a cotter pin. You need to squeeze the end of the bolt together as you unscrew it. Actually a pretty clever set up.

I tried. Bolt is solid.

Not a lot more I can add to this conversation, sorry.

Thanks anyways! Hopefully someone on here has seen something like this before.

I see a no hub clamp in the right hand part of the pivture.......is there another one on the left side of the fitting ccan you just replace
It?????????????

No that’s kind of buried underneath the ground and I wouldn’t start playing around with those lol. I’m not that qualified.

Can you ger a flat heaf screw driver and pry open the flapper??????

Yes that I can do and it goes up and down perfectly fine but there seems to be a lot of sludge on it and I want to remove it to clean it

You said you wete unable to remove the flapper so open as wide as you can and usethe fitting brush on all accessableareas that can be cleaned,lubricateany moving parts other than that if it still doesnt work
Ypu or a proffesional will have to expose the couplings use a a cordless screw gun with the appropriate nut size or small socket set and remove and install a new one