i have a 2003 f-350 7.3 diesel.i had the hood up yesterday just checking thinks out while it was running. i hear a tapping noise under the left valve cover the motor has 88,000 miles on it. would anyone have a idea what this tapping noise might be and how serious it might be

 

Its probably the #8 injector knock. Do a search for injector knock or cackle and you will get all the info you need. Hope this helps

 

I would consider doing the "in tank" and "pre pump" mods, also an HPX crossover line from one of the site sponcers will quite the motor down alot. You'll get a nice even sound, no more rattles, knocks, and tapping. Of course ive done all of those and still have injector knock, caused by a failing #8 injector I think.

 

i have a buddy that has the old body ford 7.3, (wish i could remeber the year of it) and he had a loud knock that was coming from the same place ours does with the #8, anyways he farted around trying to figure out what it was and finaly he had someone tear into the engine and it turned out to be that a piston had lost a piesce below the rings, on the skirt and that made the piston sloppy and causeing the knock, but i am sure what you have is the infamous #8 cackle, i have it from time to time, and i just keep on driving.