I bought this truck, the blow by was normal, all the fluids were clean and normal, the truck ran and drove without issues. I used it to tow my car on a uhaul trailer5 hours home and about half way through the trip I could hear the engine knocking. Using a stethoscope I listened to each cylinder and I can hear the knocking distinctly from the #7 and slightly from the #5 cylinder. When I crack the #7 injector line the knock goes away. So I bought new injectors and a new injector pump from typ4. Installed everything, new fuel filter and glow plugs. Got it running and the knock is still there. I advanced and retarded the timing a few degrees several times with no noticeable difference in the knock. I noticed when removing the old glow plug from the #7 cylinder it was kind of difficult to remove (like sliding in and out) and then putting the new one in it was tricky to slide in and get down to the threads. Could there be a bunch of carbon build up on the head messing with the glow plug and the spray pattern? For shits and giggles I checked my coolant reservoir today and I know it was perfectly clean when I purchased the truck and now there is black liquid in the bottom.... The blow by is still the same and the oil is still black and not milky (I also changed the oil when I got home no milkyness when it was drained) The only time I drove the truck was the test drive and the drive home. Here is a video of the knock and me cracking the injector line. Im ready to rebuild this motor if I have to but it needs to be done soon, i only have the remainder of this month and October while I work full time and to do the rebuild. I just need a reliable vehicle I have to tow a trailer loaded with 9000 lbs nearly 800 miles on November 1st when I move home from the military. Obviously since its an IDI I have to sleeve the cylinders and since its a turbo get the turbo piston rings. Rod, main and cam bearings and fel pro gaskets. What else am I in for?