Does anyone know what this hole is for? It spews exhaust fumes and makes it sound like I have a serious exhaust leak. Feels like I should have more power too. Don’t want to cap/plug without knowing more about it.

is it supposed to be there? Some suggestions from friends include casting leftover or testing port. I was hoping someone else with an 8.1 would chime in.

 

Looks like an engine block water plug to me.

 

If that’s the case I can just plug it no problem.

 

On some of the older model trucks, there used to be a temperature gauge sensor in that hole.