Need a little help, best way I can describe the sound is, its like a diesel running and you can here that chatter they make.
Here is when it happens, under very light load starting around 2500 rpms in any gear. Doesn't do it under heavy acceleration or under decelertion. Guesses have been rocker arm, lifter and/or maybe valve spring. Pulled the valve covers off and all rocker arms are tight except one on driver's side and it has just a little bit of motion side to side. None have any up/down play, but we did not rotate the motor at all, just checked as it stopped.
Here is when it happens, under very light load starting around 2500 rpms in any gear. Doesn't do it under heavy acceleration or under decelertion. Guesses have been rocker arm, lifter and/or maybe valve spring. Pulled the valve covers off and all rocker arms are tight except one on driver's side and it has just a little bit of motion side to side. None have any up/down play, but we did not rotate the motor at all, just checked as it stopped.