Can anyone help? Is there supposed to be a cap on the side of this? Why is all my coolant leaking out the side? I've taken it out and blown air through both ports multiple times thinking maybe it was a stuck valve or something. This radiator is not that old.... It's leaking out everything I put in. 1997 F350 Gas with Duallys

View from the top of the engine

 

Welcome to the site

Check the O ring/seal on the thumb screw end…

 

O rings are a good idea but it sure looks to me like the screw plug is not all the way tightened.
Don't force it to much or it could break.

 

So the plug was definitely tightened all the way. There was no o-ring / seal, but I put one on there and it fixed the issue.

 

Thanks for the update…