Truck Repair: n14 cummins, poor quality fuel, n14 cummins

Question
the engine rattles. sounds like a gas engine spark-knock
it does this sound above 1300-1350 rpms with a vibration
no smoke at all. please help. i'm a poor boy trying to get by in this world.

Answer
Dennies,
I tried to lay my hands on further details you provided on this question without success. Please find my answer as follows:
It is quite possible that your engine may be detonating. Detonation simply put is the burning of end gases inside a compression ignition engine.
Probable causes may be faulty injectors nozzles dripping diesel into the combustion space; injection/engine timing problems, poor quality fuel; stuck injector plunger in one of he cylinders may also be a probable cause.

Let me have your follow up actions on this.

Kind regards,