zinc anode stuck in block drain

5.9 magnum.
I put a boat zinc plug in the block drain on the passenger side. there is one on the drivers side, but it is under the starter, so I am leaving that alone.

anyway I pulled the one on the passenger side up front to drain the block.
The zinc must have swelled, because it twisted off in the block. stuck in their pretty good. And it doesn't leak.
I can't get the original plug back in because of how far the zinc sticks out. I can't get the new plug back in either for some reason. I guess the zinc must have backed out a little.

since it doesn't leak I am tempted to leave it. see if it ever blows out.
or I read (assuming it really is zinc) I can dissolve it mixing salt and vinegar to make HCL and eat it out of the hole.
I think I can pour some in a flexible tube and then hold it against the hole in the block to get it to stay next to the hole, but the question is, is it worth that time. or is it being stuck enough and just let it go till it does blow out?

can I reach it through a freeze plug? maybe bend it out from the other side?

A punch, a Hammer and gentlemoderate tapping will likely put the zinc back in the water passage and out of the hole.

I wouldn't trust it to remain leak free, because that is the way my luck goes.

Or drill and re-tap.
Also FYI: sometimes a stubborn pipe fitting or bolt will break free it you try tightening it just a bit, like a 1/16th of a turn and then reversing. Sometimes it is required to do that several times with penetrating oil. Last resort HEAT and let it cool. tips form my brother who is a retired union pipe fitter

ok, will give it a try. guess I don't have to worry about the chunkies?

the "chunkies" were exposed to the coolant to start with [although in a solid form], so i don't really see a problem if some are left.

was thinking more about damage if they circulate and hit stuff.
but I guess it is a softer metal than say the wp impeller.

Based on all the crud I've raked out of the core plug openings over the years I wouldn't worry about the anode circulating.

Agreed. "worst case" it chews up a water pump seal and those are easy to change. Zinc is a very good anti-corrosion agent. It's a self-sacrificing metal, so it will slowly dissolve and prevent rust inside your iron block while it dissolves. Don't worry about any chunks

it was pretty brittle. and a couple of hits knocked it loose enough that a bunch of water poured out.
I had to push some chunks in that held onto the sides before I could thread in the old plug. but I got it in.
Thanks for the help.

but i'm a bit confused by the bolded part. the block drains are typically 1/4 NPT. Are you saying that chukns of the block ( cast iron) broke off?

no, chunks of the zinc were still stuck to the sides of the hole.
I thought I had pushed the whole zinc in, but turned out it was just a piece of it. it just kind of was crumbly.
I was trying to put the plug in from the top so I wasn't looking at the hole, when I realized it still wouldn't go in.
looked and found it was still blocked by the zinc, even after all that water poured. out.
so I had to use the punch to knock the rest back in along the sizes of the hole.