odd intermittent knock and miss? i need some help

[carolinasmoker13]

so im new to the site and i just bought my first diesel its a bone stock 86 f250 ext cab 4spd with the 6.9. last week i decided to take the interstate home as it was late and i was tired, now normally i take the back roads as the 4spd likes to tach out on the highway and i try to save the fuel but long story short i pulled off on my exit and noticed a knock and miss in the truck and really got worried. ive read a few threads on here and have tired a few different things and some have helped a bit but its still not fixed. so my question is this, how does one know for sure that a diesel has a bent rod or spun bearing without a tear down? this is my only means of transport right now

 

[icanfixall]

WElcome to the forum. Your question is suspect in that you have gone way over to the dark side so to speak as the question is suspect. Why are you asking this. We are needing plenty of questions first. So you just got this rig. Whats the mileage on the truck. How many miles on the injectors or injection pump. Are these parts new when replaced or used. Many times a used injector or a rebuilt replaced injector is suspect. Any injector can open early and cause a cylinder knock. An early opening injector will cause a knock that sounds like a bad rod knock. so find the suspect knocking cylinder and either replace that injector or move another cylinders injector for that cylinder and see if it moves to another cylinder. So please help us answer some questions.

 

[carolinasmoker13]

sry to be vague, im just new to diesel problems. i found a suspect cylinder i.e. i cracked all the lines till i found one that didnt seem to change the idle much and replaced said injector with a new one and it hasnt made any difference. the truck has 160k on it and there is no written or spoken history on it other than i found a biodiesel filter that was seriously clogged and removed it from the fuel lines and cleaned out the tanks all a month ago. it currently has fresh oil and filters on it now with fresh fuel. i do know it needs new gps bad and ive had to use ether to start it in the mornings but im very light with it as i know the dangers. im currently waiting for my raise to kick in and once that happens i plan on new pump, injectors, and lines. but right now im just trying to keep her goin till i can make some much needed upgrades

 

[carolinasmoker13]

also i pulled the valve covers looking for sludge and loose rockers and found none of that. very clean on both sides and all were tight. im just not sure whats going on. but right now ive got the fuel filter full of atf and run through to sit in the fuel system, ive seen alot of mention of this trick working so im giving it a try hoping theres just some leftover gunk in the ip or something