Inspection and restoration of connecting rods and bearings (Mercedes-Benz E-Class W123)

A defective big end bearing can be identified by a knocking sound in the crankcase and a drop in pressure level.

1. Inspect the connecting rod bearing surfaces for chipping and scoring. Replace the liners, where necessary, with new ones of the same size. If the crankshaft has been reground, use new connecting rod bearing liners of the corresponding reduced repair size.

2. Check each connecting rod for bending, twisting and ensure it matches the stud diameter.

3. Install the connecting rods with bearing shells on the corresponding connecting rod journals of the crankshaft and tighten the bearing cap bolts to the specified torque. Check the radial offset for compliance with the specifications. If the radial offset is too great, replace the connecting rod bearing shells with new ones.

4. To remove the piston from the connecting rod, remove the snap ring from both ends of the piston pin and knock it out of the small end of the connecting rod. Do not heat the pistons, as the piston pins are installed in them on a floating fit.

5. If necessary, replace the small end bushing and piston pin. The difference in weight of any pair of six connecting rods should not exceed 5.0 g.

Text republished from the website Mercedesman.ru

6. Install the piston in a position in which the arrow on its bottom faces forward and the tabs of the bearings are directed toward the left side of the engine.