brass? its supposed to be copper, and when it fails what you get is compression from the cylinders escaping.not a good sound if its liquid diesel your getting, its from the injector bodies, high pressure lines or usually from the return lines.don't get your naked fingers anywhere near a diesel leak, if you get a tiny spec into your skin its byebye finger, or hand depending how far to the nearest hospital
ive had diesel on my finger and in my mouth and all over my face (dont ask)i didnt go to hospital and nothing bad happendi feel great