What are these called?

[PFPJeep]

Replaceing the manifold and found that 2 of these are leaking oil. After a few minutes of searching I can't figure out their name.
97 4.0

 

[jjvw]

Often incorrectly referred to as freeze plugs.

 

[Steel City 06]

They also block off coolant channels, and not oil. They're plugs for holes left behind during the casting process.

If they're leaking oil, something is very wrong. Punch one out and it would let out coolant.

Typically the one closest to the radiator is the one used to install a block heater. The heater is a small 600 watt heating coil on a replacement plug.

 

[PFPJeep]

Thought it was oil, but you are correct. Coolant

 

[PFPJeep]

Thanks for the replies

 

[Blackjack]

Often incorrectly referred to as freeze plugs.

Yep you will hear a few different names for them. Freeze plugs, soft plugs, casting plugs etc. Correct term for them is Expansion plugs but you are better off calling them freeze plugs when you go to the parts stores as even Melling refers to them as freeze plugs.

 

[jjvw]

Yep you will hear a few different names for them. Freeze plugs, soft plugs, casting plugs etc. Correct term for them is Expansion plugs but you are better off calling them freeze plugs when you go to the parts stores as even Melling refers to them as freeze plugs.

The claim that these plugs will pop before the block cracks in the event of the coolant freezing never made any sense to me. That isn't how freezing liquids work.

 

[PFPJeep]

So I'm assuming I should drain the coolant and replace all the plugs while I have the manifold off, correct? Or attempt to seal?

So far on this particular job.
Replaced the valve cover gasket, PCV valve, breather valve.
Cleaned the throttle body
Cleaned the injectors and replaced the "O" rings.
Put heat shield on the fuel rail and injectors
Cleaned and degreased a bunch of other parts...

 

[Blackjack]

The claim that these plugs will pop before the block cracks in the event of the coolant freezing never made any sense to me. That isn't how freezing liquids work.

Yeah it is not like water behaves like expanding foam and looks for the open hole lol. I am sure a few plugs have been pushed out but then you have to ask what about all the water below the plug?

So I'm assuming I should drain the coolant and replace all the plugs while I have the manifold off, correct? Or attempt to seal?

So far on this particular job.
Replaced the valve cover gasket, PCV valve, breather valve.
Cleaned the throttle body
Cleaned the injectors and replaced the "O" rings.
Put heat shield on the fuel rail and injectors
Cleaned and degreased a bunch of other parts...

Yes while you have easy access drain the coolant and replace the plugs.

 

[TJ4Jim]

The claim that these plugs will pop before the block cracks in the event of the coolant freezing never made any sense to me. That isn't how freezing liquids work.

Freezing water expands here, what does it do by you. lol