Bathroom sink started draining slowly

[Hudson]

A few months ago I noticed that my bathroom sink started draining slower. If I wait 20 seconds, everything drains OK. The drain has been there since 75. I took the trap out and made sure that it was clear. Everything that I could see was clear all the way to the wall.

I went up on the roof and looked into the vent pipe....using a flashlight. It was clear all the way to the bottom.
What's my next step?

 

[WorthFlorida]

It's probably the sink drain. Remove the sink stopper buy removing the lever (pivot rod) to the drain. Pull the stopper out from the top and it may be just loaded with crud. After forty years the drain may be falling appart from corrosion or plastic parts crumbling. This is fairly easy fix & cheap by replacing all if it is the sink drain causing the problem.

http://cdn-2.hometips.com/wp-content/uploads/2012/06/bathroom-sink-plumbing-diagram.gif?8fa5ce

 

[Sponsor]

 

[Standardairconditioner]

WorthFlorida is correct. The blockage can be in the sink often where the overflow meets, or in the pivot mechanism if it is internal within the drain path.

If you were able to remove the p-trap, try to remove the drain tailpiece too. That's the area that drops down from the sink to the p-trap.

 

[Hudson]

Thanks WorthFlorida and StandardAirConditioner!

I have either removed or looked through the pipe from the sink to the waste pipe. It is clear. I did remove some gunk from the bottom of the tail piece...but I don't think that was causing the issue. It still doesn't drain normally.

Where would you go next?

Disregard above...it's fixed. I took the commode plunger and plunged it hard about 10 times. It's OK now. I never thought about plunging a sink...until now. I should've done that first.