Kitchen sink backing up

[BullheadPond]

Having problems with my kitchen sink backing up. Have snaked the whole drain Down to the 6 inch pipe. used draino gel and other drain cleaners. still backs up. See drawing attached.
Probably only 10 feet before the smaller Drain pipe goes into the 6" pipe under the house.
Replace the Sure vent with a new one and it still backs up. it is the only one that backs up. Not sure if it is an air lock or what? Wondering if the clean out pipe could be the problem? Never seen one under a sink ? Anyone have any ideas?

Attached Files:

 

[DIYorBust]

How does it drain with the surevent removed?

 

[Sponsor]

 

[BullheadPond]

How does it drain with the surevent removed?

Don't think i ever tried leaving it off and running the water.

 

[Reach4]

When you put water into one bowl, it backs up into the other, I presume.

If the sinks sit unused overnight, how many gallons of water does it take before you start seeing backup? You can pour water from a 5 gallon bucket to gauge that.

 

[BullheadPond]

When you put water into one bowl, it backs up into the other, I presume.

If the sinks sit unused overnight, how many gallons of water does it take before you start seeing backup? You can pour water from a 5 gallon bucket to gauge that.

Gallon or less.

 

[Reach4]

Gallon or less.

add up the length of the 1.5 inch pipe from each drain, to the junction, through the trap through the cleanout... When you get to 10 ft total, the clog is before there..

If you have standing water, open the cleanout over a bucket. How much flow do you get? If more than a quart, then use the cleanout, but with a wider cutter than just 3/8 inch.