Laundry plumbing backing up issue

[Slipknot]

OK, I have a recent issue I will describe best I can. This did happen years ago once or twice also when I had water leak into the basement underneath. When the Speed Queen washer discharges after the wash or rinse, sometimes bubbles come out where the hose goes into the waste pipe in the wall and also gurgles up thru the bathroom sink on the opposite wall and water can come back up into that sink but it will then recede down and empty pretty quickly. That sink drains for 10 feet maybe before connecting to the 2" in the basement so it's not like it is right there, I find it odd that suds will make water backup that drain as well, maybe since the sink drain is at a lower elevation, the water goes up the path of least resistance IDK. The laundry has been fine for 25 years and has only a 1-1/2" pipe in the wall that goes into a 2" vent then down the wall into basement(2") where it has the sink drain(1-1/2") connect into it then leads out.
I ran 25 feet of snake into it and there is zero backup, not even a piece of lint.
Both waste pipes are vented properly.
I think it has something to do with the wife stopped adding vinegar to some loads of wash and the winter time cold water temperature is a lot colder than warmer months so it is affecting soap conditions in the washer if that make any sense. She was using some powder Oxi something along with some liquid detergent but a lot of times it would still have powder in the tub after washing, I told her dissolve it in water first if she adds that.
I did searching online and found that this happens to others as well. Speed queen website states using liquid fabric softener can help and I also read don't use the NORMAL/ECO mode that only has one rinse cycle and uses less water. We used to use that all the time. I also read to run empty washes with bleach to clear out excess soap, or vinegar or washing machine tablets that are supposed to clean it all done in hot water. We did 5 or more runs like that.
So now she uses a small amount of liquid fabric softener and pods for soap even though we have always used HE detergents, and now if she does one load - it seems to drain well and the floor is not wet but when she does another load right away within 30-40 minutes I'm guessing, it backs up in the sink again.

I think it is a soap suds issue but I don't understand how water cannot go around or thru soap bubbles.

my next effort if I don't want to wait an hour or so between loads will be to change out the laundry waste pipe to 2" in exchange for the 1-1/2" in the wall behind the washer, I already opened up the sheetrock to see it all. I am not sure that will even matter.

Any advice?
Thanks

[Redsoxticket]

I knew someone that purchased a new washing machine that was overflowing at the waste water pipe and the solution was to extend the vertical height of the waste water pipe.
Posted from my iPhone/Mobile device

[Nebe]

yean i would extent that pipe higher. Also another thought.. have you had your septic pumped lately? sometimes the filter in the septic tank gets clogged up partially and it will create back pressure.

[Slipknot]

It is extended pretty high
And it goes to a drywell
Posted from my iPhone/Mobile device

[Guppy]

Originally Posted by Slipknot

It is extended pretty high
And it goes to a drywell
Posted from my iPhone/Mobile device

Dry well ! ….
Really wet year, could be backing up ,,,, washing machine lint is a major contributor to leaching failure….

Now that I think of it, it’s probably clogged with sawdust….. ;-)

[Slipknot]

Originally Posted by Guppy

Dry well ! ….
Really wet year, could be backing up ,,,, washing machine lint is a major contributor to leaching failure….

Now that I think of it, it’s probably clogged with sawdust….. ;-)