Island sink drain doing "glug, glug" slow flow rate

[pbierre]

The drain is backing up. When the dishwasher pumps out, the garbage disposal fills past the top with waste water.
As it drains down slowly, you hear the "glug, glug" sound associated with poor venting.

I built this island myself, and know how the drain is vented using a loop. This morning I opened the vent pipe cleanout to see if this provided additional venting. It did. The "glug, glug" went away and the drain flowed freely. When I repaced the vent pipe cleanout cap, I was expecting to be back to "glug, glug", but it seemed fixed. But now a few hours later, it's clear nothing was fixed.

Was opening the vent pipe a good test? Would a clogged drain only make that "glug" sound?

How do you clean out a vent pipe? Can you use pressurized air? Vacuum? Do you have to snake it? We're talking a 1-story house.

 

[breplum]

UPC design requirement for island loop vent requires a c.o. at the foot vent where it starts the vertical portion, in addition to c.o. for the drain. Snaking everywhere is called for.
If no foot vent c.o. then snaking from the roof is the way.

 

[pbierre]

Thanks, fortunately I put in 3 c.o.s:
• Under sink, In vertical loop about 6" higher than drain
• In garage, accessing roof vent pipe 36" above and 36" lateral to kitchen drain
• Subfloor, in horizontal waste pipe that receives drain and vent loop verticals

Glad I kept photos of all my plumbing for kitchen island.

Will be snaking from garage.

 

[Jeff Handy]

Once you clear out the clog, start using something like this every few weeks, or at least once a month.

Cheap insurance.

Especially if there is a food disposer on there.

A partial clog or narrowed drain can push old slime and yuck up into the vent, as a holding area, until the drain can allow everything to clear out.

64 oz. Drain Defense Liquid Pipe Build Up Remover

https://www.homedepot.com/p/202056509

 

[frodo]

you have a partial blockage in the line
when the line backed up. it caused waste to enter the foot vent.
now you have waste in yur vent.
take a rag, tie it to a 3/8'' spring snake. and scrub the vent line from the co in the wall back to the island
make damn sure the rag is secure or it will come off.

 

[pbierre]

I could only get 7' of 1/4" snake in from the garage. Five 90-degree elbows (2") and it just stops advancing.

Drain rate through garbage disposal is about 8 gal./30 sec (16 gal./min). At the end, there is a "glug, glug" for about 15 sec.

Is the flow rate normal?

Is there something within the garbage disposal that could be making the sound?

 

[pbierre]

Draino gel put into garbage disposal, 15 min. soak time, followed by 10 gallon flush (using stopper to fill sink). I conclude that the blockage was local within the garbage disposal.

The glug-glug sound is gone!

 

[Riickk]

My preventative for kitchen drains w/disposers is: Once a month, fill sink with water, turn on disposer, remove sink's stopper. Flushes away most anything in drain line.