Instructables

How do you open a clogged plumbing air vent to a kitchen sink?

We are having a plumbing problem with the  kitchen sink draining. The dishwasher ( for the most part) drains, but the kitchen sink does not. We have  tried the regular drain cleaners with no success. Then on the Internet it said to try sulfuric acid. When he went to Lowe's to get the acid, the Lowe's man suggested another really good drain cleaner and we tried it, it was something that you put so much in for 3 days. It didn't work. Last night we tried the sulfuric acid, sink still not draining. Or I should say , it drains very very very slow, pretty much takes several hours to drain.
He has also been up on the roof checking to see if there was a bird nest or something blocking the vent. He didn't find any obstruction. He used a plumbers snake and he could put it down through the vent until it reached water. However , the plumbers snake did come loose from the handle, and now it is in the vent. We don't know how to get it out, or if it will be a problem in the vent.
....and he did not take a hose up to the roof and run water into the vent. That is the only thing I see that we have not done yet. He has taken all the pipes apart under the sink and run the snake under there as far as he can, there is no clog under the sink that we can find. Those drain pipes are all put back together. The plumbing in the rest of the home all works properly.

A few questions. Is it a single or double sink? Is there a garbage disposal attached? What type of pipes are used? Have you tried useing a plunger on the sink to force water thru? (*DANGER* Don't attempt this if there is still acid in the water in the sink!! ) How long was the snake? These may help answer some other problems you could be having.

First off I would want to get the snake out of the air pipe. I don't think it would cause a problem but it could, depending on where its at, cause a clog later. If there are 2 sinks, with a disposal attached, look where the pipes meet. There is a angled piece inside the pipe that directs the flow down coming from the disposal side. Some times food can block this up and since its inside the pipe you have to pull it apart and look inside to find it.

Try pouring boining hot water directly into the drain after it has went down. Sometimes grease build up can clog and some chemical treatments just don't reach where it needs to, to melt it. I hope by you useing the acid you have metal pipes. If there are PVC pipes you may have done more damage that will come back to haunt you later.

Do you have access to the main drain clean out from the house? If so you could try to snake from that direction. I don't think it would help since you say no other drian in the house is affected.

At most hardware stores they have a rubber bladder type thing (blow out plug or soomething) that attaches to a garden hose for a few bucks. You feed the hose into the pipe and turn it on. The bladder swells up inside the pipe and the water pressure then forces any blockage thru. I've seen these but have personally never used it so can't give better discription sorry.

Hope one of these helps. I'll check back and see if you add any more to this, it may help figure out where or what the blockage is.
rocknlinda (author)  RedneckEngineer2 years ago
We finally got it unclogged!!! YEA!!!! We tried all of the suggestions, such as the hot (boiling) water, the rubber bladder thing screwed onto the end of the hose etc, nothing was working. The main clean out drain to the house was running fine. It turns out there was another HIDDEN clean out drain under the sink. Once it was found and opened up we could see the plumbers snake that was lost into the roof vent. We were able to pull it out with a pair of pliers. Then an electric plumbing auger was run into that clean out drain. That did the trick!!!! Opened the drain everything is working beautifullll now. We did have a scare from one person that had said because of the drought we are having here in Texas that the house had probably shifted and broke the pipe. Praise the Lord, that was not the case.
I want to thank all of you for your helpful suggestions.
Glad to hear you solved it! Out of curosity where was the hidden clean out at? It might help if I ever run into this again to know where to look. Yea that would have been a high pucker factor on thinking the pipes were broke!
rocknlinda (author)  RedneckEngineer2 years ago
It is a little hard to explain but I will do my best. At my sons home (where this all took place) his sink is at an angle in a corner. So there is a very large area under the sink. As you are looking at the sink the dishwasher is on the right side. There is a cabinet wall for the sink cabinet. On the back kitchen wall at floor level and partially obsecured with the cabinet wall that butts up to the dishwasher was the hidden clean out drain. All of the other drains, hoses, garbage disposal, dishwasher hose, etc. are easily seen and accessible. This clean out drain was not! We know it's there now though!!!!! Our homes were built at the same time by the same contractor. So I wondered if I also had a hidden clean out under my kitchen sink. So I came home and looked for it and mine is in plain sight under the sink on the back wall at midlevel.
We were defintely concerned about the possibility of the pipe being broken. Texas has had 40 ++ days of over 100 degrees and we have had no rain for months and months. There have been news reports of numerous main line city water pipes that have broken because of the heat and the drought. I am glad this pipe was not broken.
rocknlinda (author)  RedneckEngineer2 years ago
It is a double sink with a garbage disposal on the right side. It is PVC pipes. Yes we have tried plunging the sink. If I had to guess, I would say the plumbers snake was about 10 feet long.
We also would like to get the plumbers snake back out of the vent. However we have no idea how to do that. We wonder if the plumbers snake has already washed through the pipes.
We do have access to the main drain clean out. It has been snaked and there is no clog there.
I have not heard of that rubber bladder thing before. I will look into that. And I will try the boiling water.
Thank you very much.
Re-design2 years ago
If the dishwasher drains but the sink does not then the problem is not the vent pipe.

The vent pipe will not cause slow draining in any case.  It is there to keep the drain from sucking out all the water from the p trap.

You have a blockage between where the dish washer connects and the sink that won't drain.  Unclog it and your sink will drain again.
gneal Re-design2 years ago
Thank you for your help. I've been having this problem with our kitchen sink at our office building. I've been thinking about calling in some commercial plumbing, but I read this post and we I figured out the problem without having to call in a professional! Thanks a million!
Or you may have a clog further on down the line.
hmacdiarmid2 years ago
You can get a special fitting for a larger auger that will retrieve lost cables, the fitting looks a little like an open spring that expands out the way, so as it spin the lows cable will get caught in it and you can pull it out.

You might want to try a larger electrical auger, something like the super-v or larger. You'd probably have to rent one, cheaper than a plumber.

If you want to know if its a plugged vent you can always put water down the vent (on the roof) if it backs up into the sink then the blockage is in your drain, if the water backs up out of the vent and not in the sink then you have a plugged vent. Having a plugged vent is very rare.

if you try the bladder thing make sure and insert it past the T for the vent, otherwise the water will just be forced up onto your roof.
Kiteman2 years ago
Dopey question, but have you tried taking the sink's U-bend off and giving it a manual clean-out?

rocknlinda (author)  Kiteman2 years ago
Yes we did that.
Thanks
framistan2 years ago
Be carefull. If you loosen any pipe, the sulfuric acid could come out and get in your eyes or skin. Usually, sinks get stopped up because of GREASE going down the drain. Then it gets into the "U" shaped pipe and hardens because the temperature of the water in the u-bend is cold. One time i unclogged my kitchen sink by simply running HOT water into a cooking pot like one you would cook soup in. Then I held the pot under the sink in such a way that the "U" shaped pipe is SUBMERGED into the hot water. Hold it there for 2 or 3 minutes so the pipe gets warmed up. This melts the grease and it will flow again and suddenly the clog loosened and the drain was clear. Most likely, that is what is wrong. If that doesn't do it, then i would
let the water run SLOWLY so that the sulfuric acid slowly drains away (you said the drain flows slowly.) Then, when you are sure all the acid is gone, then someone should remove the "U" shaped trap under the sink so you can clean it. If this trap is PLASTIC it is very easy to do. If it is METAL, it is much more difficult. When replacing it, it is a good idea to throw away the metal "U" pipes and replace them with plastic ones because they don't rust and are easily removable for cleaning.
rocknlinda (author)  framistan2 years ago
The acid was our last resort that had been suggested to do. Prior to using the acid, we had already taken all the plumbing apart under the sink, cleaned it all out, and used the plumbers snake to go through the pipes that we couldn't take apart. There was no clog found anywhere in this area. Then those plumbing pipes were put back together. That is when someone told us to check the vent on the roof. We found no obvious obstructions in the vent on the roof.