I have a 99 4.0 ohv, just rebuilt the motor and found while installing torque converter nuts that the crank would just come to a hard stop when turning it. stops at top dead center when going clockwise and 10 degrees to the left of tdc when going counter clockwise, only thing i can think of is that maybe i messed up the timing installing the cam synchronizer, but im really not sure

 

what did you rebuild? what was replaced? was the motor rotated before install? you could pull the cam sensor out and ck? but I dont see how that could do it?

 

it has new pistons, valves, cylinder heads, camshaft, timing chain, only thing that i think i could have messed up is timing but im not sure if that would cause it to lock up like that

 

when you were working on it im sure you turned it over many times? cam sensor I can't see how it could do it be to make sure you could pull it to ck. im not up on Auto trans but guessing something is wrong there?