Procedure for taking Main Engine Bottom End Bearing Clearance

Lead Wire Method : Its the traditional method, but requires that bearing are tightened just to obtain clearance. the procedure for taking clearance is as follows
1.  Turn the crank shaft and set the crank at TDC position. 
2.  Remove locking arrangements, mark the nut position. 

3.  Slacken the nut and lower the bottom half with bolts. 
4.  Then three lengths of lead wires would be laid circumferentially in the bottom half at three places. 
5.  Place the bottom half into position and tighten the nut to its tightening torque. 
6.  Lower down the bottom half again.

7.  Remove the lead wires and take the measurement. 
8.  It must have within the limit, if out of limit, the bearing shell must be replaced with new ones or readjust the clearance by adjusting shims. 
Feeler Gauge Method: Its a quick method, but more difficult to be accurate when using the long feelers. The procedure for taking clearance is as follows
1. Turn the crank shaft and set the crank at BDC. 
2.  Insert the feeler gauge between lower half and crank pin. 
3.  Take the measurement readings.


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  1. where do we fit adjusting shim if ME bottom end bearing clearance is more?

  2. Replies
    1. at other position bearing is under load.

  3. Bottom of the connecting or piston rod foot we have to add
    Just type marine foot connecting rod u can understand
    In this crank pin bearing is not required to be opened to take out piston
    As like in compressor

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