i bought a 96 cummins with a knock as a project. the truck white smokes and it is real low on power. the guy said it was a rod knock but it has oil pressure. i thought it was a fuel knock but i changed the fuel filter, had my injectors checked and they were fine. i pulled the head off and piston #2 was kinda clean and i can spin it side to side and it clunks like it has a bad wrist pin. would a bad wrist pin cause real low power? it has a fine scratch in the cylinder wall. you can feel it with your finger but my nail doesnt really get caught in it. thanks for any help.

 

define low on power

 

barely moves. i can back out of driveway and floor it and it doesnt accelerate fast at all. i can try to powerbrake it and it wont even come close too turning a tire over. i had trouble getting it too drive up on a car trailer.

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So i pulled the pan and the #2 rod bearing is destroyed. Would that cause it to run like crap? Do I have to pull the motor to take the crank out or can i do it with it in the truck?

 

you need to pull motor to take crank out. if the piston has any kind of movment in the cylinder, NOT good.

Since you bought this for a project, I would do a complete rebuild, these motors are fun to work on and are not that hard to rebuild, they are also not the exspensive to rebuild, as long as you do the work yourself.

Good luck

 

I have no problem doing the work myself. I just don't feel like buying a bigger engine stand and pulling the front of the truck off. That's why i was asking.