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Hi guys. I feel like an idiot, but is this a freeze plug? It is so small, and I never really paid any attention to it until it started leaking. 1968 327ci.

Looks like it's one of the drain plugs if I looked at the right picture. Should just be an NPT pipe plug.

any idea what part to order for a fix? does it come in a kit with freeze plugs?

That's one of the coolant drain plugs on the engine block!

Passenger side drain plug, or what's left of it if broken.
Could be missing the plug entirely and this is the rust sediment behind the drain plug.
Any brass 1/4 NPT male plug - Lowe's or Home Depot. Wrap threads with teflon tape, one turn and install 1/2-3/4 turn with wrench from hand tight. you di want to be able to remove it when changing antifreeze.

OR - if using the TPI ECM, you might just screw in the knock sensor as this is the place to install it and hook up the shielded wire to it.

Nice car by the way.

Thanks! Problem is... I don't see any threads in the hole. Does it just push in like a regular freeze plug?

NO!.....It threads in!

how do i get it out if it looks like that. no threads showing... no way to get a wrench on it...

May have to chiesel it out and retap if threads are damaged!

You might think about a screw extractor. You can find a set at almost any hardware/tool store. You drill a pilot hole and use a funky bit that pulls the broken bolt/screw as you crank the bit in.

I'd poke a small screwdriver in the hole just o see if its sediment first before drilling and tapping.

Besides, if it is a broken plug, does it leak? If not, don't fix it - could be more trouble than what's its worth.

I agree with others, you could try tapping your way thru but don't get wild, cly wall on the othe other side.
Could also use a bottom tap, run a short brass plug and forget it.
If no threads, you could clean up hole, insert a shallow dish plug, tap the center to expand and seal.
I would prefer to clean up and tap. May need this hole one day to drain water in block. Could also wait until motor come ever comes out.

When I build engines I always replace the plugs with radiator petcocks. Makes it way easier to drain the block. I agree it's very possible the plug simply isn't there and what you're seeing is rust buildup in the hole. It's at the lowest part of the water jacket in the block & all kinds of crap collects there over the years. The thing that baffles me is that they're usually in there REAL tight since they are tapered pipe thread. I've never seen one fall out.

Agreed, I think GM is on the Fourth Generation of gorillas in the assembly line, maybe the Fifth.

Yes, I change them for petcocks to drain later.

Nope... it was an expansion plug. Tapped on it with my screwdriver, and it fell apart. No threads. Bought a 1/4 expansion plug. Waiting for the block to cool before I tap it in!