Piston: Service and Repair

Piston and Connecting Rod Overview






1 Bolt

• 30 Nm + 90° (1/4) additional turn.

• Always replace.

• Lubricate the threads and contact surface.

• Tighten to 30 Nm to measure the radial play, do not tighten the additional turn.

2 Pressure Relief Valve

• 27 Nm

• Opening pressure 1.3 to 1.6 bar.

3 Oil Spray Jet

• For the piston cooling.

4 Connecting Rod Cap

• Pay attention to the installed position.

• Due to the way the separated connecting rod breaks (cracks), the cap fits only in one position and only onto the respective connecting rod.

• Affiliation to the cylinder mark - B -.

• Installed position: The marks - A - point to belt pulley side.

5 Bearing Shell

• Note the installed position, refer to => [ Bearing Shell Installed Position ].

• Do not interchange used bearing shells (mark them).

• Axial play new: 0.10 to 0.35 mm.

Wear limit: 0.4 mm.

• Measure the radial clearance using Plastigage:

New: 0.02 to 0.06 mm.

Wear limit: 0.09 mm.

Do not rotate the crankshaft when measuring the radial play.

6 Connecting Rod

• With a cracked bearing cap.

• Separating a new connecting rod. refer to => [ New Connecting Rod, Separating ] Procedures.

• Only replace as a set.

• Affiliation to the cylinder mark - B -.

• Installed position: The marks - A - point to belt pulley side.

7 Circlip

8 Piston Pin

• If difficult to move, heat the piston to 60 °C (140 °F).

• Remove and install using a pilot drift (VW 222 A).

9 Piston

• Checking, refer to => [ Pistons, Checking ] Testing and Inspection.

• Mark the installed position and the cylinder allocation.

• The arrow on the piston face points toward the belt pulley side.

• Install using a piston ring compressor.

• Cylinder bore, checking. Refer to => [ Cylinder Bore, Checking ] Testing and Inspection.

• For the correct piston and cylinder dimensions, refer to => [ Piston and Cylinder Dimensions ] Piston and Cylinder Dimensions.

10 Piston Rings

• Offset gaps by 120°

• Use piston ring pliers for removal and installation.

• Marks face toward the piston crown.

• Ring gap, checking. Refer to => [ Piston Ring Gap, Checking ] Testing and Inspection.

• Piston ring groove clearance, checking. Refer to => [ Piston Ring Groove Clearance, Checking ] Testing and Inspection.

Bearing Shell Installed Position





The bearing shell - 1 - with a oil bore - arrow - is for the connecting rod.

The bearing shell - 2 - without a oil bore is for the connecting rod cap.

- Place the bearing shells centrally into the connecting rod and cap.

Dimension - a - must be the same on the left and right sides.