Tractor Repair: perkins diesel knocking, perkins diesel, wrist pins

Question
I have a MF135 Perkins 3 cyl diesel engine that is knocking around the fuel injector..Fuel pump was recently replaced but engine oil was not changed at time of replacement so fuel could have been mixed with the oil..After running under load for 2 hrs knocking began, then I changed the oil..A friend say its possible bearing and/or rod damage, but knocking noise is up high on motor..Without hearing the noise yourself do you have a best guess as to what could be going on here and how I should proceed? thanks

Answer
Hello,

  Noises are some of the hardest things to diagnose sometimes, because the noise can travel through the metal in such a way that it can make it sound like it's coming from somewhere else.  The first thing to do is to check all the valve clearances and adjust them if necessary.  If the noise is still there, there's no other choice than to remove the oil pan and start checking the bearings and crankshaft.  If nothing is found there, check the pistons and wrist pins.

                           Good luck,

                                Arnie