Help please! new 87 6.9 IDI

[Ian Rebmann]

I just bought a 87 f250 6.9 diesel IDI. I have a international school bus with the same engine so I've climbed around it a bit. The lift pump gave out about an hour into my ride home after I towed it back I ensured it was the lift pump causing issues by ensuring flow from tanks, aswell as no flow to the fuel filter. Replaced the lift pump and bleed the stream and she fired right up. A knock started to occur pretty much right away, it did not go away after 20 minutes of warming up. The knock seems to be coming from the front right cylinder. My initial guess is the injector is clogged. This knock also sounds the same as the one that started as she was stalling on the way home from lack of fuel from the pump failure. Just today as she was running I cracked the nut that secures the metal fuel tube from the pump to the injector the engine bogged a little but the knock remained. I was hoping that was an indication of the source of my problem. To check I did the same to each injector and the result was the same so now I'm not sure. I'm a bit of a novice when it comes to diesels. Motorcycles are more my cup of tea. If anyone has any advice before I start replacing the injectors then pump I would love to hear it! I am also thinking of putting some clear hose in place of the traditional fuel lines to see if any air bubbles are still stuck in the system. There is little to no white smoke from the exaughst.

 

[Skidtech]

It is not uncommon to see a bent pushrod do that especially if the truck has been sitting very long. It would also be worth it to pull the glow plug for that cylinder I have seen the tips of glow plugs break off and rattle around the cylinder until it is either beat small enough to exit the exhaust or until it breaks a valve.