help.. for a couple of years my sump pump was smelling musty and runs very often, while the rest of the block doesn't run at all. i am in a townhouse, when i finally got in there with a flash lite, i found a hole about 1' x 2' on side of liner.. i see gravel all in there.. I just can't afford to have a new liner installed, on fixed income.. is there a way i can cement this wall closed? or is it hurting anything by leaving it this way? i think during a dry spell i may be able to use quick dry cement in there to seal it some what.. thank you

That hole in the sump pit liner belongs there. It is allowing ground water to enter into the pit so the pump can pump it away. Do not seal this hole.
As far as musty odor, I assume it is sort of like a wet dishrag smell? That is a sign of mold. Check around the basement or have it checked by a professional. Water issues cause mold. Not something you want to fool around with.

the hole is irregular in shape and i know it wore away... the sides actually crumbled.. it's still crumbling.. it looks like its rusted, but i don't think its metal..Strange i know, but color of concrete.. maybe is concrete but very thin..

It is the layers of clay wearing down from the water. Nothing to worry about. When they make the hole they take a hammer and break though it. That is why the edges are so ragged. You can try to cement the edges but it will not last very long as the cement has nothing to adhere to. Plan on a new pit. They cost around $50 at the big box stores. If your handy you can put it in yourself. If not hire a handyman to do it for you.