My heater hose nipples in the engine bay were corroded. The left one had holes and leaking for me, JB Weld with high heat epoxy overlap the holes and create a semi smooth cylinder surface for the hose to go over. I placed high heat rtv to prevent any coolant slipping out from un even surface and has been holding strong. Will be replacing my heater core from my parts truck when an issue arises, but I noticed these nipples are usually corroded from my junkyard visits.

 

Did yours leak into the cab? Or just the engine bay