Connecting Rod: Service and Repair

Pistons and Connecting Rod Overview

• Lubricate all bearings and running surfaces.

• Oil injector jet for piston cooling, refer to => [ Oil Spray Jet for Piston Cooling ].






1 Bolts

• 50 Nm + 90° additional turn

• Replace

• Lubricate the thread and contact surface

2 Connecting Rod Bearing Cap

• Mark for installation later

• Use color to identify the cylinder and connecting rod to which it belongs, refer to => [ Mark Connecting Rod ]

• Installation position of connecting rod pairs, refer to => [ Connecting Rod Installation Position ]

3 Bearing Shells

• Make sure the tabs are tight

• Replace any worn bearing shells

• Oversized bearings are available for reworked crankshaft connecting rod journals. Refer to the Parts Catalog

• The connecting rod tabs are above each other

4 Connecting Rod

• Always replace as a set

• Use color to identify the cylinder and connecting rod bearing cap to which it belongs, refer to => [ Mark Connecting Rod ]

• Installation position of connecting rod pairs, refer to => [ Connecting Rod Installation Position ]

• Axial play for each new connecting rod pair: 0.20 to 0.45 mm

• Radial clearance, measuring, refer to => [ Connecting Rod, Measuring Radial Clearance ] Testing and Inspection

5 Locking Ring

• Replace

6 Piston Pin

• Removing and installing, refer to => [ Piston ] Piston

7 Piston

• Mark the installation position and cylinder allocation, refer to => [ Piston Installed Position ]

• Removing and installing, refer to => [ Piston ] Piston

• Replace the piston if there are cracks on the piston head or piston shaft

• Piston and cylinder bore, checking, refer to=> [ Piston and Cylinder Bore, Checking ] Testing and Inspection

8 Piston Rings

• Gap, measuring, refer to => [ Piston Ring End Gap, Measuring ] Testing and Inspection

• Measuring side clearance, refer to => [ Measuring Piston Ring Side Clearance ] Testing and Inspection

• Use piston ring pliers (commercially available) for removing and installing

• Installed position: The "TOP" marking or side with writing faces the piston crown.

• Offset gaps by 120°

Piston Installed Position





The coating on the piston crown could be destroyed.

• Mark the allocation to the cylinder on the piston crown with paint to install used pistons. Do not mark the piston head with a punch, notch or something similar.

Installed position:

• The arrows on the piston heads point to the belt pulley side.

Mark Connecting Rod





• Only replace the connecting rods as a set.

- Mark the connecting rod and connector rod bearing caps to each other and to the cylinder - arrow - with paint for installation.

Connecting Rod Installation Position





• The molded tabs - arrows - on the beveled surfaces of the connecting rod pairs "1 and 2", "3 and 4" and "5 and 6" must face each other.

Oil Spray Jet for Piston Cooling





1. Insert the bolt with locking compound and tighten to 9 Nm; locking compound, refer to the Parts Catalog.

2. Oil spray jet with spray nozzle valve (opening pressure 2 to 2.4 bar)


The oil spray jets could get damaged.

• Do not bend the oil injector jets.

• Bent oil injector jets must be replaced.