Piston: Description and Operation

Pistons and Connecting Rod Overview





1 Piston Rings

• Offset gaps by 120°

• Use piston ring pliers for removal and installation.

• "TOP" faces toward the piston crown.

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

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

2 Piston

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

• Mark the installed location to the connecting rod and affiliation to cylinder.

• The two deep valve recesses in the piston head point toward the center of the cylinder block.

• Installing, refer to => [ Piston, Installing ] Service and Repair.

3 Circlip

• Ensure the circlip is securely seated.

4 Connecting Rod

• Only replace as a set.

• Affiliation to the cylinder mark - B -.

• Installed position: the marks - A - must align.

5 Bearing Shell

• Note the installed position.

• Do not interchange used bearing shells.

• Bearing shell retaining tabs must be firmly seated in the notches.

• Axial play new: 0.05 to 0.31 mm, wear limit: 0.40 mm

• Check radial clearance using Plastigage, new: 0.02 to 0.07 mm, wear limit: 0.10 mm Do not turn the crankshaft when checking the radial clearance.

6 Connecting Rod Bearing Cap

• Affiliation to the cylinder mark - B -.

• Installed position: the marks - A - must align.

7 Bolt

• 30 Nm + 90° (1/4) additional turn

• Replace

• Lubricate the threads and contact surface.

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

8 Cylinder Block

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

• Crankshaft overview, refer to => [ Crankshaft ] Service and Repair.

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

9 Piston Pin

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

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