1998 Honda civic water pump plastic or metal inside (OEM)?
OEM have plastic impellers. pretty sure.
nearly all honda water pumps are all metal construction...including this one.
Water pumps are metal including the frame, the water pulley, and the fins on the other side. Plastic fins would not be ideal as it would spin constantly and come in contact with hot coolant for the duration your engine is on. Eventually, it would soften, bend and become insufficient in pushing and circulating coolant throughout your engine. Hope this helps!
