first post looking for help...

great forum, been lurking for a while. finally registered to see if i could get some help on a recent project.

i had my basement finished ~15 yrs ago, had a liberty 1/3hp sewage pump installed in a pit for the basement bath that was added. that pump did great. i never had problems with it. i started getting worried about it being so old so i just replaced it before there was an issue. i upgraded to a liberty 1/2hp LE51A with a float.

i didnt change anything else when i did the install except for install a new check valve because the other one was inside the pit. there is a vent pipe that comes up and ties into a toilet vent, the discharge comes up and ties into the main house drain. for some reason they didnt go up and back down so that it ties in from the top, instead it goes in from the side. not a big deal since its been that way for 15 yrs.

heres my dilemna. for some odd reason the pump will run every 2-2.5 hrs when it rains. i started thinking it was either the check valve thats above the sump has failed allowing water from the rest of the house to fill the pit, BUT even if no water is used in the house, it still runs after 2.5 hours. i dont think its the check valve because i can hear the water hammer noise when it shuts.

then i started thinking it was the septic tank backing up into the house when the ground gets saturated after a hard rain, but i opened the trap outside the house during the storm and theres no backup of water.

then i started wondering if the vent system was getting water in it somehow and filling the pit that way. is it possible that rain could enter the roof vents(i have 3) and somehow fill the pit, it is the lowest point in the house. i highly doubt that THAT much rain fills the pit, that would be a lot of rainwater.

i ran the shower, sink, and toilet and it appears that the sump is emptying correctly and with the right amount of water. i was worried the float switch was hung, maybe the pump shifted and the float is sitting up against the wall of the pit but i doubt it.

this never happened before i changed the pump. nothing else changed with the system. water is getting into the pit someway when it rains. it doesnt do it when its sunny and dry outside.

Seems like you were thorough in your trouble shooting.
Hard to see the whole picture from here.
Have you looked into the sump to see if the float is hanging up or if you can see a flow of water actually filling the sump when it's raining?

you said nothing changed almost sounds like there is a French
drain tied in the only thing you could do is pop the cover during
rain and see whats happening

i dont hear anything dripping, ie from the main inlet, or vent line, and i know the check valve is working.

now im concerned the basin might be cracked allowing groundwater from all the rain to be forced into the basin. hope thats not the case.

im dreading opening it up but i guess thats what i need to do.

you had said you had opened it recently anyway....if your
worried about the bolts take one to a hardware store and change
them all outgo stainless then put some heat grease one them

You probably done this already but make sure the arrow is pointing up on the check valve. If not water would just pump and stay in pit and eventually burn up the pump. Sounds like the only thing different from before is new pump and check valve above lid.

yeah that was the first thing i checked. its installed right. i ordered a clear silent check valve to install so i can see if its working and not stuck open.