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66 Coupe 289 v4 3 speed
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Discussion Starter · #1 ·
So I'm stripping my block down so I can know what I'm working with. Last night started taking out the freeze plugs and I'm pretty sure this bolt goes to the coolant also but mine is stuck and doesn't want to move. Started rounding the head off so going to let is sit for a few days with PB blaster and try heat. When I'm done I'm going to replace this so need to start looking for a new one but don't know what it is called.



This is not my engine but you can see it clear in the photo so using this photo because I don't have one.


Auto part Engine Automotive engine part
 

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That is a coolant drain plug for the block, doesn't usually have a hex head, normally has a square head, 3/8 of an inch I think. Try that size or similar open end wrench or a bolt-out of the fitting size, clean those passages out good.
You can replace it with a brass plug or valve with a little bit of thread tape and make it easier to open for a flush later on.
 

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66 Coupe 289 v4 3 speed
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320 Posts
Discussion Starter · #4 ·
That is a coolant drain plug for the block, doesn't usually have a hex head, normally has a square head, 3/8 of an inch I think. Try that size or similar open end wrench or a bolt-out of the fitting size, clean those passages out good.
You can replace it with a brass plug or valve with a little bit of thread tape and make it easier to open for a flush later on.



Yes mine is a square head but like a idiot I rounded it off, started with open wrench it started rounding so I moved to channel locks rounded more so stopped and heated it up and sprayed PB on it will tray again tonight. Was able to get the other side out no issue.


My plan is get the plugs out and pressure wash the block very well and use a brush to get everything off. Once that is done spray it with a light coat of oil until I get it all painted and rebuilt.



Thanks for the info, I just added those to my cart at NPD $4 for the set is a good deal.
 

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I just drilled the exact same plug out of my block on Sunday.
It's not hard with sharp bits.
Keep enlarging it until just before the threads show, then use a punch to fold it up on itself, and then pull it out.
I left the three oil gallery plugs in the back of the block. I'll let the machinist get them out.
 

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I just drilled the exact same plug out of my block on Sunday.
It's not hard with sharp bits.
Keep enlarging it until just before the threads show, then use a punch to fold it up on itself, and then pull it out.
I left the three oil gallery plugs in the back of the block. I'll let the machinist get them out.
You should try to remove them, or tell the machine shop to. The plugs close off the back end of the oil galleys, but on the front they are closed off with soft plugs. The front holes can be tapped for screw in plugs as an added measure of safety.
 

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Those square head plugs are a real pain to get out as you found out. When you replace, use the hex head plugs that should come in the core plug kits. They are much easier to deal with.
 
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