Previous homeowner was victim of watching too many DIY reality shows, nothing has been done correctly or works like it should. If this IS correct, then I will eat crow.
Tall pipe on the left is where the washing machine drains into. There is a utility sink on the right side fitting. No venting. I don't know if the 2" running up the wall runs to a main vent, if it is its own vent, or if it's used as a drain from something upstairs. I will check and find out.
When the washer drains, the sink fills up near to the top. I don't know if I have an obstruction or if it's due to lack of vent; or a combination of both. I'm going to try and clean everything out just in case.
I'm doing a small remodel on this laundry room (mainly just painting the concrete walls, replacing the sink, installing a cheap floor...ripped out black-molded carpet that was used in the laundry room...WTH???)
Left supply lines are for the washer. Right is for the sink.
Old drain. Won't work with the new sink. Old sink was raised 1" off the floor just so they had clearance.
Thinking the drain T needs to be moved to the right a bit, and then done correctly, with the correct fitting.