[annem915]

I have a 50's built house with I'm assuming iron piping. I have some clogging of the vent pipes and the toilet flushes but water rizes a little but it goes down.
I'v managed to unclog the shower drain but it seems that it steal might be slightly clogged cause when I ran in the water hose in from outside I could almost have it wide open before it would backup. (have city water coming in but a septic tank going out).
I am able to see into the pipe between the house and the septic and that is not clogged or backed up.
When I stand facing the outside wall with toilet in between us there is a 3" vent pipe to the left approx 2' (have not clue why) and a shower drain to the right approx 3' which is attached to a T drain that seems to go to the outside and back into the bathroom to an old sink drain that has a 4" vent pipe.
My ? Is is there a U trap under the slab between the toilet and drain or were they required to have them back than, and do you think the 2-3" pipe left of the toilet is its vent pipe cause thats the one i'm having trouble unclogging and have had water on floor from trying because it leaks now.
Or is it the big 4" vent pipe connected to the shower drain because sometimes we would get a smell from there when we flushed the toilet.
Any help or suggestions would be Appreciated, Thank You!