Need advice on fixing washing machine overflow

[Vicky01]

• older home with 1.5” copper piping
• Laundry ties into kitchen drain
• overflows from washing machine within 10-20 seconds
• Can withstand full pressure from outdoor hose for more than a minute before slowly overflowing. Will drain if allowed at a lower rate.

Have had multiple plumbers out who do not know what issue is. They’ve tried snaking but had trouble getting past the “T” elbow”.

Any advice or insight would be deeply appreciated thank you.

 

[breplum]

modern code for laundry is 2"
I personally have a 1-1/2" drain stubbed out at the floor framing that I put a 2" trap and standpipe on and it has worked for 30 years
Unfortunately you are going to need some plumbing change and your situation sounds like plumbing surgery, the degree of which depends on what piping you have.
Ultimately the solution is a 2" drain, which kitchen line should be too. though, we see old 1.5" copper drains for both from the bad old days.