i've got a bad rattle that doesn't sound as deep as a big end bearing. really noticeable when the engine is at temperature. clearly heard in neutral. when driving the car the noise isn't there under full throttle acceleration, it's when you come off the throttle or on the overrun or light acceleration.

the engine is in pieces now as i've taken it apart looking for obvious signs of wear. #4 big end bearing has very bad pitting grooves on them and was stuck on the crank journal to the web on the right. all the others came off easily except that one. part of the #4 big end bearing had split too. but the noise seemed too high a pitched rattle instead of a deep knocking.

any ideas? i'm going to take to water pump off to see if the impellers are ok