metal particals in frame filter cap

[hopperwagonbob]

I have ask this question before but didnt get a real clear answer. so here it is again. when I changed my fuel filters at 6000k the frame mounted filter cap had shiney glitter in the cap. tore the filter apart an found nothing and the engine mounted one was fine. did this come frome the tank? or did it come return fuel? this was the first filter change. thanks! also will an airdog help if the tank is contamenated. or is it to late. have always used fords cetane booster.

[Stroke4Fun]

Mine was the same way when i did my first change at 10k the answer i got was it was from the fuel you never know what you are pumping! I have changed them two times since them and have not seen the metal so i don't know!
Chris