I am having a problem with a bathroom sink totally backed up. I can solve most problems with snakes or CO2 cartridges, but this one has me baffled. All of the other drains attached to the vent stack are working properly (tub & toilet). I took everything apart and snaked out the drain behind the wall. I then used a Drain King attached to a garden hose. The water just went up the stack vent and spilled out on the roof, and I still have a clogged drain. Later, I went up on the roof and can see water about 10 feet down (the total length of the vent stack is about 20 feet. Everything below the bathroom sink drain is working properly (tub drain, toilet, and basement shower drain, basement toilet, and basement sink. I was thinking about snaking out the vent stack, but I'm worried I may push any object further down and clog the rest of my drains (tub & toilet). The sink drain is 2 inch galvanized, and the vent stack is 4 inch cast iron. One story ranch house with basement was built in the late 50's in Michigan. Is this something that I can do myself?

The water just went up the stack vent and spilled out on the roof,
You have a blockage at the base of the stack that must be snaked from the roof. You might want to rent a regular sewer machine,(see image) to do this. Put out enough snake to reach the base and 18 feet more. Leave your Drain King in the house when you go up on the roof. Good luck, Tom