There is a fine line when it comes to making log book entries. There are many things to take into account before you put pen to paper. I would suggest having a discussion with your engineer prior to putting anything in the log book. I have witnessed more than one occasion where the First officer writes up an item while the captain is not present. Upon the captains return we inform him he will not be flying this Aircraft because of lack of parts or the write up was a grounding item. Several of these were smaller items that the captain was fine with till they terminated at a maintenance base. Needless to say it was a long walk up the jetway for the F/O with the captain yelling at him. The more time you fly you'll figure out what to put in the logbook and what to put on scratch paper. Good Luck
