Piston: Service and Repair

Pistons and Connecting Rod Assembly Overview





1 30 Nm plus an additional 90°

• Replace

• Lubricate the threads and contact surface

2 Connecting rod bearing cap

• Do not interchange

• Mark allocation to cylinder using a color marker - B

• When installing bearing cap, observe: The wide thrust flange - A - must point to the same side on connecting rod and connecting rod bearing cap

3 Bearing shell

The version depends on the construction:

• Lower bearing shell (for bearing cap), identified by a dark-colored bearing. Upper bearing shell (for connecting rod) made of wear-resistant material, identified by a light-colored bearing

or

• The same bearing, no allocation

• Check that retaining tabs are secured

• Mark used bearing shells for reinstallation but not on the running surface

• Replace the bearing shells worn down to the base layer

4 Connecting rod

• Only replace as set

• Mark allocation to cylinder with paint - B

• When installing bearing cap, observe: The wide thrust flange - A - must point to the same side on connecting rod and connecting rod bearing cap

• Radial clearance, measuring => [ Connecting Rod, Checking Radial Clearance ] Connecting Rod, Checking Radial Clearance

5 Piston pin

• If tight, heat piston to 60 °C

• Removing and installing using a Drift (VW 222 A)

6 Circlip

• Replace

7 Piston

• Arrow on piston face points toward belt pulley side

• Checking, refer to => [ Pistons, Checking ] Pistons, Checking

• Install with piston ring compressor

• Piston and cylinder dimensions, refer to => [ Piston and Cylinder Dimensions ] Piston and Cylinder Dimensions

• Cylinder bore, checking, refer to => [ Cylinder Bore, Checking ] Cylinder Bore, Checking

8 Piston rings

• Offset gaps by 120°

• Use piston ring pliers for removal and installation

• "TOP" marking or inscribed side must point to piston head

• Checking ring gap, refer to => [ Piston Ring Gap, Checking ] Piston Ring Gap, Checking

• Check piston ring groove clearance, refer to => [ Piston Ring Groove Clearance, Checking ] Piston Ring Groove Clearance, Checking

Installed position of piston and piston/cylinder allocation





- Mark installed position and allocation to cylinder on piston head using chalk or waterproof felt pen.

• Do not use a center punch or scribe, since the piston head coating will be damaged.

• Installation position: Arrow on piston face points toward belt pulley side.

Mark connecting rod





• Only replace connecting rod as a set.

• Do not interchange connecting rod bearings.

- Before removing, mark allocation of connecting rod and connecting rod bearing caps to each other and to cylinder with paint - arrow -.

Connecting Rod, Installed Location





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

Oil Spray Jet for Piston Cooling





1. Install the bolt - 9 Nm - using a locking compound.

2. Oil spray jet with spray nozzle valve

CAUTION!
• Do not bend the oil injector jets.

• Bent oil injector jets must be replaced.