Piston: Service and Repair

Piston and Connecting Rod Assembly Overview





1 Bolt, 30 Nm + 90° (1/4) additional turn

• Always replace

• Lubricate the threads and contact surface.

• Tighten to 30 Nm to measure radial play, do not turn further.

2 Bolt with Pressure Relief Valve, 27 Nm

• Opening pressure: 1.3 to 1.6 bar.

3 Oil Spray Jet

• For piston cooling.

4 Connecting Rod Bearing Cap

• Note 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 -.

• Installation position: Marking - A - point to the belt pulley side.

5 Bearing Shell

• Note the installed position, refer to => [ Bearing Shell Installation Location ] Bearing Shell Installation Location.

• Do not interchange used bearing shells.

• Axial play: new 0.10 to 0.35 mm.

• Wear limit: 0.4 mm.

• Measure radial clearance with Plastigage.

• Radial clearance: new 0.02 to 0.06 mm.

• Wear limit: 0.09 mm.

• Do not turn the crankshaft when checking the radial clearance.

6 Connecting Rod

• With cracked bearing cap.

• Only replace as set.

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

• Affiliation to the cylinder mark - B -.

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

7 Circlip

8 Piston Pin

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

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

9 Piston

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

• Mark installed position and cylinder allocation.

• Arrow on the piston face points toward the belt pulley side.

• Install with a piston ring compressor.

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

• Piston and cylinder dimensions. Refer to => [ Piston and Cylinder Dimensions ] Piston and Cylinder Dimensions.

10 Piston Rings

• Use piston ring pliers for removal and installation.

• TOP marking faces the piston crown.

• Offset gaps by 120 degrees.

• 2 part oil scraping ring.

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

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