Questions for the plumbing gurus

[Enigmatic]

I have a 80+ year old house.
It has the original cast iron waste & vent in it. It is rusting thru & the oakum has fallen out in areas.

That's just one problem. Another is the house has separate drains. The sink & washer dump into a "Y" pipe that leaves the house at one end & goes to a French drain out in the yard. That pipe has broken & the washer pump backs up in the kitchen sink now.
It quit draining down last week.
So, a friend of mine who is a plumber came out & installed the kitchen drain back to the sewer cast iron pipe instead of the 2" PVC pipe it had to run out the other drain. He cut a pipe that had a vent on it that tied it with the "Y" from the washer pump. Now, the "Y" pipe from the kitchen drain backs up into the shower stall in the bathroom behind the kitchen.
Since the pipe was cut, there is no vent to the kitchen drain or the bathroom on the other side of the wall from it.

Would hooking the "Y" pipe back to the kitchen drain pipe provide the vent it needs to drain?

I know, clear as mud, right?

[EatenByLimestone]

Is it a vent issue, or is it an issue of trying to force too much water through too small of a pipe? Your old cast iron pipe may be much, much smaller than the original ID due to rust along the inside and not allow the water to go down quick enough.

[Enigmatic]

The plumber told me he thought it was a vent issue. But what gets me is that it all worked before the other guy tied the kitchen drain back into the cast iron & did away with the French drain side.
I am literally at my wits end trying to figure out the truth behind what the first guy did, besides cut the original 2" PVC drain line to the outside of the house.

[Roly]

The plumber told me he thought it was a vent issue. But what gets me is that it all worked before the other guy tied the kitchen drain back into the cast iron & did away with the French drain side.
I am literally at my wits end trying to figure out the truth behind what the first guy did, besides cut the original 2" PVC drain line to the outside of the house.

I agree with Matt, sounds more like a restriction or clog in the drain line.  Why was it connected to the french drain ?  Roly

[EatenByLimestone]

How big are the pipes below the shower? Are there any clean outs that you can access to see how much capacity the pipes really have?

You may need to run a power auger down the pipes in order to open them back up, and then decide if you need to replace more of the system.

[Enigmatic]

The shower drain is a 1.25" pipe that ties into the cast iron main.
The 2nd guy ran a snake down the shower drain about 30' so I know he was clear into the 4" cast iron main drain.

Like I said, everything was working fine until the 1st guy tied the kitchen drain back into the cast iron main.
I think he cut off something & sealed it off.
I will have to go check it out myself some more & see if I can figure out what happened.

[joe1086]

1.25" is pretty small for a shower. Pretty sure the standard/minimum requirement is 2.5".

[Enigmatic]

It might be a 1.5" pipe. I've never seen a 2.5" drain on any shower.

[joe1086]

Sorry, meant to say 2", not 2.5.

[EatenByLimestone]

My snake is 3/8, maybe a half inch wide. It could run down a straw and not have an issue. A sewer auger would be better at maybe an inch wide. The power augers come with different sized heads.

I know my cast iron pipes have crap built up around the inner surfaces.