How to remove sink strainer with no nut on the bottom or top

[pasadena_commut]

Redoing the drain under our double kitchen sink. Bought a kit with all the parts (supposedly) to hook up the drains and the disposal, but it only works if the disposal moves to the other side. That's OK with me since the disposal is being replaced too. Unfortunately, after removing all the pipe from the side of the sink with the strainer what is left has no obvious means of removal. There is no nut on the bottom, no nut on the top, no thumbscrews or set screws. The picture is from the bottom. The top shows the other side of the bottom of the strainer and then just smooth metal. (Edit: well, there are 5 slightly raised vertical regions distributed around the inside of the cylindrical cup above the strainer, but I certainly don't have any tool that would fit that.) I thought about putting a big screwdriver in the rectangular hole and turning it, but it is probably stuck on pretty well, since it has been in place for at least 28 years, and possibly as long as 65 years. No way to get a grip on the partial hemisphere part, for instance with a strap wrench, it would be like trying to grab the top 1/4 of an orange.

My best guess is that I'm supposed to bang on one of the 6 raised flanges around the perimeter, for instance with a block of wood and a hammer, to cause it to unscrew. Hard to believe though that it was installed like that.

Is there a better way?

Thanks.

 

[pasadena_commut]

Ah, I see now, that big ring is a lock nut, the last thread is just peeking out below it on one side. So in theory it might turn with a strainer locknut wrench, which of course I don't own.

On the negative side, the brown goop coming out a few holes near that nut is petrified plumber's putty, which suggests to me that it might also be on the threads, which would make unscrewing it really hard, with any tool. Guess I will bang on it for a while and hole it breaks free.

 

[MicEd69]

If you have a Dremel tool, you can use it to carefully cut that nut on two opposite sides. There is a rubber gasket on the bottom that you can see that will give you a little leeway in the depth of your cut so you don't cut into the sink. Once the nut is cut onto two pieces, you can pry it off and the strainer will pull right out.

 

[pasadena_commut]

We

Once the nut is cut onto two pieces, you can pry it off and the strainer will pull right out.

Well, you were half right.

The nut was cut once through with an oscillating tool and then broke into pieces and came off with a little prying with a screwdriver.

Unfortunately, the strainer is still solidly stuck in there. I spent 5 minutes banging on it from the bottom with a rubber mallet and it hasn't moved a millimeter. The same approach took out the mount for the old Insinkerator disposal in about 30 seconds. I put that disposal in around 25 years ago with plumber's putty. The stuck strainer looks like it was set with something like plumber's putty but this stuff has aged (possibly over 65 years) to a consistency somewhere between glass and concrete. The sink is I think porcelain over steel, and I don't want to bang on it too hard lest the white stuff cracks.

 

[pasadena_commut]

Got it out, finally.

There was a pretty thick black felt(?) ring under the locking nut all around the strainer. Got out the razor blade scraper and painters multitool and removed all of that. This revealed a ring of (very hard) plumber's putty between the strainer and the sink. Scraped out the putty most of the way around, to a depth of about 3/8" using the painter's tool, a screwdriver, and a small steel pick. The strainer was not centered in the hole, it was pressed up against one side with a lot of putty on one side and none at the contact point. Also removed all the plumbers putty that was inside the grooves corresponding to the ridges mentioned above inside the cylindrical section of the strainer, as this extended down into the rest of the putty.

Then a couple of good blows with the mallet and the strainer popped out.

Sections of what I think is plumber's putty were a dark brown color, the rest was the usual sort of gray.

How clean does the sink need to be before putting in the new pieces? The razor will remove the putty from the smooth parts of the sink, but the rough parts underneath do not clean up as easily.

 

[MicEd69]

You do not have to clean all the old putty or whatever that material is as long as it is hard and not crumbly. A stainless-steel "sponge" scrubby or some course or extra course steel wool would get it clean enough to install the new strainer.