Hi all, I need a little advice regarding coolant loss. Recently my truck seems to losing/leaking coolant. Hoses and radiator seem to be fine, coolant appears to be dripping from under the engine. I have enclosed a pic, showing (excuse my ignorance here please) the hole where the fluid appears to be dripping from. Should this hole have a plug? Should coolant even be in there? Truck is a 95 Silverado 5.7l Any advice would be much appreciated, thanks.