Stinky kitchen overflow!!!!!

[graypam]

Double kitchen sink has been fine until recently (no changes or additions made) when it started to smell really bad. I've taken off the u-bend, cleaned it out, removed and unblocked overflow pipe. Water flows very freely now but there is the most disgusting smell coming from the overflow now. I have tried putting "Drain Magic" down it, when that didn't work, I put loads of boiling water down it, I've even tried thick bleach but nothing has worked. I am considering taking a small toothbrush to it and see if that makes any difference but I'm not sure whether it would fit from underneath due to the closeness of the sink bowls.
I would greatly appreciate any other suggestions because I really don't know how much longer I can cope with this vomit-inducing smell!

 

[JohnD]

provided you have assembled your trap correctly, it sounds to me like you have grease and food deposits.

bleach kills germs but does not attack grease or remove deposits.

scrape and scrub off anything you can reach

try Washing Soda (available in crystals from grocery shops on the household cleaners shelf) it attacks grease and breaks up food deposits. for best results leave it to work overnight and flush with boiling water

Train your household never to pour grease, fat or oil down the drain. wipe it off pans with kitchen roll and throw in bin, or pour into empty can or dish and give to the birds.

tealeaves and coffee grounds go in the bin too.

 

[graypam]

I never thought I'd get to the bottom of this stinky problem! I eventually got my hubby to remove the waste pipes from the sinks (totally took them apart) and oh boy! that was the problem. The previous owners of the house (we only moved in here a couple of months ago) obviously used their sink as a waste disposal unit! It was caked with grease and gunk and stank to high heavens! After being scraped off, washed in boiling water and put back together, I now have a stink-free kitchen sink!

Thanks for your advice!