I have an older bathtub with a "plunger drain" setup like this:
I can see the very top of the plunger's linkage assembly (it must have become detached from the trip lever linkage at some point, and sit's much lower in the drain now) and it has an "O" that I can get a hanger or hook around with some work.
The issue is that the plunger won't budge. It's almost as if it's lodged or rusted tight. When pulling with a coathanger bent into a hook, it takes me pulling so much that it unbends the hanger without moving. I don't feel any noticeable sign of give or wiggle.
Unfortunately, the drain opening is not an open drainpipe (it's some kind of closed stopper valve) so I can't try to do anything through there.
Is it likely that the plunger, itself, is jammed in there? Or, perhaps it's rusted? I considered throwing some DW-40 down there, or something to see if it might loosen. But, I figured I should ask first. I'd hate to open a wall, since it backs up to another shower, requiring me to demolish the siding to get access.
Best Answer
I would stay away from the acid because it can also eat your metal pipes. If the drain hasn't been used for years it is possible that it's rusted in place. I would try CLR as mentioned above. The balloon trick is clever. Slow process but it MAY work. Most older drains are brass and the stopper is also brass. Corrosion is more likely the culprit. Once you get it free you can pull the entire assembly out through the overflow hole to clean or replace it. Good luck!