4.3 mercruiser

[Bigsprad]

Hello.
I was summarizing my ski boat and it had a 2 piece block plug. I was screwing the smaller Allen key piece into the larger piece, and it threaded into the block. My question is: is it safe to just replace the plug? Or do I have to remove the one in the block because it will cause damage? Thanks very much for any feedback...
Kevin

 

[achris]

"4.3 Mercruiser" covers a LOT of engines.

Can we have a year, and serial number please. Also, which 'block plug'? There are several.

Chris......