Piston: Service and Repair

Piston and Connecting Rod Overview






1 Bolt

• 45 Nm + an additional 90° (1/4) turn.

• Always replace.

• Lubricate the threads and contact surfaces.

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

2 Bolt with Pressure Relief Valve

• 27 Nm

• Opening pressure: 1.3 to 1.6 bar pressure.

3 Oil Spray Jet

• For piston cooling.

4 Connecting Rod Bearing Cap

• Pay attention to the installed position.

• Due to the separation procedure (cracking) of the connecting rod, the cap only fits in one position and only to the corresponding connecting rod.

• Mark which cylinder to which it belongs - B -.

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

5 Bearing Shell

• Note the installed position, refer to => [ Bearing Shell, Installed Position ] 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(R):

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.

• Always replace as a set.

• Mark which cylinder to which it belongs - B -.

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

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

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 => [ Piston, Checking ] Testing and Inspection.

• Mark the installed position and 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.