Yesterday afternoon, I found a slight leak coming from the kitchen sink drain, right at the top,near the strainer/ rubber washer/cardboard washer.
I tried to tighten the big locknut, but the leak continued.
Last night, I replaced it all: new putty, strainer, 2 washers, locknut, and reassembled the drain. So far so good, after running a lot of water, no leak.

Currently, while there is no leak,I think that I could make the locknut tighter, but I don't want to over-tighten anything, and possibly cause another leak or damage the drain.
My question: how tight do I need to make the locknut? Do I leave it "as is", and only tighten it more if the leak reappears? or..??
Any suggestions are appreciated. Thanks in advance.

 

I would stick with your "tight enough" approach. I have gone too far and ended up cracking the nut so I would not go tighter just for the sake of it.

 

Run hot water down the drain for several minutes. Then give the nut a snug... If it snugs a little then it was too loose... If it dont budge with great effort then its tight enough...

I never leave a home without running hot water and snugging all nuts....

 

Wow, 2 differing replies from 2 gentlemen who have never steered me wrong.
So what did I do:
I checked the existing tightness, and it seemed like I'd need to apply a lot of force to make the nut tighter. I then ran hot water for 5 minutes, and tried again. This time, the locknut moved, somewhat easily, approx an eighth of a rotation before snugging up again. I left it at that, still no leak, but to be safe, there is a small bucket underneath the drain!

Thanks again, gentlemen.

Mike, a follow up question: what does running the hot water do, that shows that you need to snug things up a bit more?

 

Expands all the metal, plastic or what have you so you can make things tighter.

Usually on a call when a plumber does not do this, there usually is a call back for a leak down the road...

Why? Because the homeowner runs hot water, dish washer for a few days and the joint you thought was tight loosens up from expansion and leaks..

#1 call back a plumber faces is this IMO...

 

That clarifies it rather nicely! It is a process that i'll be sure to use as/if the need arises.
Thanks again.

 

2nd trick is use teflon paste on all washers and threads...

I do this on track homes mostly... Why? Because the water is usually off on not on to the home yet...cant run hot water or leak test...