Cummins ISX air in fuel return line

Hello! Ive been going through the same problem, started with vibration on accelaration and a diffrent pitch or sound hard to describe. Started by changing motor mounts,then mid-shaft bearing,pulled oil pan just to check and replaced rods and mains,and oil pump,then went to turbo no problem,went to fuel side and like you found black substance in fuel and air in the inlet fuel and the return.replaced fuel line from tank then transfer pump fixed the inlet air problem. Replaced pump,complete fuel block (minis actuators and shut-off) still had air in return and shutter on top end . Replaced injectors and found out the black substance is alge looks like burnt motor oil.injectors cured vibration but still had the return air problem. Several say in will have air in return.alge-x or killem for alge problem that starts in the tanks.this has wore me out!!!

 

yes the injectors fixed the shutter. i got the injectors from TRUCK-PRO for 340.00 each. but i could still hear the noise it is hard to describe but it was sort of like haveing the back windows down in a 4 door car, sort of a beating, but not in the exhaust,and yes only 30 psi on manifold pressure. the charge cooler was checked again and is now leaking,why all this at once i dont know? getting a cooler from radiators-r-us out of des moines ia. for a w-900 for 485.00. hope that takes care of the noise will find out wed.or thur. hope this may help you.