I have a 1999 345 that was in a fire. I cleaned it up, put the flywheel back on and tried to turn the motor over with a socket on the flywheel nut. It turned about a quarter turn and then it would not go any farther. I noticed the intake valve one the left side was stuck. I broke the valve loose but I still can not get more than a quarter turn. All the pushrods seem to be in place. I do not think I have a valve hitting a piston. Is it possible for a tappet/valve lifter to dislodge and not allow the cam to turn?