F250 Knock

[dannymoz71]

Hi, first off please excuse my signature for being Chevy. I am asking a question about my moms truck. I am a mechancic in the army and help her with it whenever I can, currently stationed in Korea so cant really look at it myself.

She has a 93 F250 extended cab 4X4 flatbed. It has a 7.3L turbo deisel and a five speed tranny. About six months ago it developed a harsh knock. I looked at it best i could means i didnt have much time (on my way here) and didnt have any tools with me. To me it sounded like something in the fuel system, and she had had the injector pump replaced recently so I told her to have the injectors checked out. The place she took it pulled the injectors and found one had a broken tip. So they pulled the head and removed the tip from the top of the piston,and replaced that injector. Ran good after that. Then she drove it from Iowa to South Dakota. While there it developed another knock. It occurs after the truck has warmed up and is noticable in the mid RPM range. At highway speed it is not noticable. So she took it to the dealership there where they pulled that head off again and found a peice of glowplug stuck to the top of the piston, but not much else. They also changed the oil and found some copper fillings in the filter. 1200 dollars later they hadnt fixed anything, and all they could say was they thought it might be the cam bearings. The mechs around her cant figure it out and she is getting tired of paying them for guesses and new parts that dont do anything. If anyone has a suggestion, idea, or has encountered this problem please help.

[AmysTrooper]

Go to ford truck enthusiasts . com
Free to register and they will answer your question,sorry I can not.

[ModMech]

Well,

If they "removed a piece from the piston", and did not replace the piston, you have big problems.

The pistons in these engines are NOT capeable of being used once they get this type of damage. It is not unlikely that one of the two pistons that had a FO in it broke, which is now causing the noise.

It could also be that the timing is just wrong, but they are easy to time, so that is not supre likely, but definately possible.

With one injector and one GP tip broken over such a short period, there may be some other issue (like improper GP control use, poor service procedures etc) at play.

[dannymoz71]

It wasnt a peice of the glowplug they removed, it was a peice of the injector tip that was stuck to the top of the piston.

[unclebubbles]

I dont know what the deck height, or the piston skirt clearence is on that engine, but if the pieces of injector/glow plug they found on top of the piston (s) got squezzed between the head and piston, it could have caused piston damage, rod damage, rod bearing damage, or a combination of the above. Those rods and pistons are pretty healthy, but when a piece of metal gets between the piston and the head, its like the piston running into a brick wall for a moment. It can crack the piston, especially in the wrist pin boss area.(which is what your noise sounds like based on the description) It can bend the rod , sometimes enuff to cause the piston skirt to hit the crank counterweights, and it can also cause bearing damage. All of this could contribute to the metal shavings they found. Just a few possibilities to have checked. Good luck.
Later
Ed