What is this hole in my block for?

[810wagn]

I was staring at my motor earlier today and I saw this hole that I hadn't noticed before, What is it for and does it need to be plugged or does something go into it? Im confused...

 

[Eomund]

I'll take a look at my motor when I get home to confirm, but that looks like a freeze plug hole.

[K_trip]

- removed -

[datsunaholic]

It's for the PCV.  The location threw me- I'm used to 4-cyls being midblock.  Didn't realze 6-cyls were so far forward.  No, you don't want to plug that.

[TENDRIL]

nope do not plug it!  you will star blowing valve cover gaskets oil pan, mains sometimes, and cause other issues ..

[darrel]

When you turn the engine upside down, there is a plate held on by two screws, behind the plate is a mesh screen folded a few times. Basically a flame arrestor.

[datzenmike]

I don't think a flame arrestor as the PCV valve is a spring loaded one way valve that closes if there in an intake backfire. The 'fly screen' is to provide a large porous surface for oil mist to precipitate on and run down into the pan

[810wagn]

Ahh, crankcase breather.. duh. Thanks guys!

 

How is the vent tube held in there? Does it get pressed in? I just don't see anything that would secure it on there so oil doesn't seep out.

[datzenmike]

It's just a very snug slip fit. The tube is supported elsewhere and can't fall out.

[810wagn]

Cool, thanks for the help!