Triumph Repair: coolant leak, circular indentation, coolant leak

Question
75 TR6.I have a coolant leak in an unusual place ie just behind the front of the manifold there is a circular indentation in the block and there is a pinhole in it that squirts fluid out. It appears to be something that pops out and can be replaced but i can find no reference to this in my manual. Any idea what i am dealing with and also how to repair it? The area is just inside of the heater return pipe ath the rear of the water pump. Thanks

Answer
this sounds like a typical " freeze plug " leak. pretty much any engine has them. they are suppose to bust out if the water in the engine freezes thus saving the block from damage. with modern antifreeze it isn't too much to worry about. they are steel and will rust thru eventually. that sounds like what has happend. most auto parts stores or Victoria British can look it up and get a replacement. you drain the water and punch into it with a screwdriver and try to work it out pliers might help also. once it's out, clean the hole with a Dremel tool and wire brush so you have a clean place to put the new one in. you put some permatex #1 on the edge and tap the new one in  (around the edges ) and then give it a hit in the middle . that spreds it tight . that should fix it. DM