1985 6.9L Slight Knock Sound
 

Hey guys, i just picked up my 1985 F250 with a Banks Sidewinder turbo'd 6.9L IDI and it has a slight knock sound at idle that is very persistent. Its not loud, but you can definitely hear it. As I start to drive, it becomes sporadic and only makes a noise every 2-4 seconds depending. Is this the Fuel Knock issue ive read about due to a bad/failing injector? Also, i dont know how reliable the Oil Pres gauge is, but i read about 7-9 psi at idle after the truck is warmed up. It has about 20 psi when the engine is cold. Any ideas on where to start tackling these issues? Am i gonna hurt the truck daily driving 40mi with this knocking sound? Its my only transport to work, and i have to make it on time everyday.