Answer:-The following precautions should be taken prior to carrying out a crank case examination of the main ngine.
•At least 20 minutes should elapse after the engine is stopped before any attempt to enter the crank case.
•The safety check list for entry should be carried out and the check list duly filled up.
•the crank case must be thoroughly wiped and made free of smeared oil so that no one slips inside and injures himself..
The following checks and clearances are to be measured.
•The clearances , using the appropriate or long feelers, of the top end bearings, the bottom enfd bearings and the main bearings must be taken.
When checking top end bearings the clearance is taken from the top when the crank is on TDC.
When checking bottom end bearings, the clearance is taken on the bottom side with crank on BDC.
•Guide clearances are to be taken at top, mid stroke and bottom.
•All holding bolts must be hammer tested for tightness and the locking devices checked for their intact condition.
•The bottom end bearing must be checked by nipping the bearing using a long crow bar to check for free movement of the bearing on the crank pin.
•The Main bearing clearances are checked from the top side of the bearing with the webs turned to the starboard side.
•The tie rod pinching screws must be checked for their tightness. Missing pinching screws must be fitted and suitably tightened.
•The sweepings from the crank case are checked for metal particles and other impurities . This is necessary to investigate any undue wear from bearings and other components.
•The cam shaft chain sag on the slack side is to be measured for record.
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