That is the location of a core/freeze/expansion plug. When they cast the block there are holes on the outside where they can go into the block and knock out the sand cores used in casting the block. The holes are those access points. After they clean up and machine the blocks they get blocked with a metal plug like are in the image. They can rust out or sometimes they get pushed out if the coolant in the engine isn't good enough to keep it from freezing if it gets very cold. If you live in an area that got really cold in the past weeks then that is the likely issue. Or it could be that someone had replaced one and didn't use a quality part and it failed.
When they are out in an easy place to access replacement is simple, you take the new plug for that location, make sure it is clean and clean out the port it goes into, then you select a socket or similar driving tool that fits in the cup side of the plug. Now apply a thin coat of sealer around the edge of the plug and line it up square with the hole and use a hammer to drive the plug into the hole until the edge of the plug is level with the block around it.
Now if you are in an area where it got cold and that pushed the plug out, you will want to check all of the others as there could be more that are about to fail. The same applies if the plug rusted out as well.
A video about them.
https://www.youtube.com/watch?v=lqHVNqwKMBI
However if it was struggling there could be a bigger issue if you are in a cold climate area.
Feb 25, 2021 at 5:25 PM
