Piston and Connecting Rod Assembly Overview

Piston and Connecting Rod Assembly Overview





1 Piston rings

• Offset gaps by 120 degrees

• Position the oil scraping ring offset gaps closely in the wound area of the spring

• Use piston ring pliers for removal and installation

• "TOP" faces toward piston crown

• Checking ring gap => [ Piston Ring Gap, Checking ] Piston and Cylinder Bore, Checking

• Check piston ring groove clearance => [ Piston Ring Groove Clearance, Checking ] Piston and Cylinder Bore, Checking

2 Piston

• With combustion chamber

• Mark installed position and cylinder allocation

• Installed position and allocation, piston/cylinder => [ Installed Position of Piston and Piston/Cylinder Allocation ]

• Arrow on piston face points toward belt pulley side

• Install with piston ring compressor

• Replace if piston skirt is cracked

• Checking piston position at TDC => [ Piston Position, Checking at TDC ] Piston Position, Checking at TDC.

3 Piston pin

• If difficult to move, heat piston to 60° C

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

4 Circlip

5 Connecting rod

• Mark the allocation to the cylinder using a color marker - A -

• Installation position: Markings - B - point to belt pulley side

• With cracked bearing cap

6 Bearing shell

• Note installation position => [ Bearing Shells, Installation Location ] Bearing Shells, Installation Location

• Note version:

Upper bearing shell (to piston) made of wear-resistant material, identification: Black line on contact surface in area of separating point

• Do not interchange used bearing shells

• Insert bearing shells in center => [ Bearing Shells, Installation Location ] Bearing Shells, Installation Location

• Ensure seated tightly

• Axial Clearance, Measuring

Wear limit: 0.37 mm

• Measure radial clearance with Plastigage(R):

Wear limit: 0.08 mm (do not turn the crankshaft when checking radial clearance)

7 Cylinder block

• Cylinder bore, checking => [ Cylinder Bore, Checking ] Piston and Cylinder Bore, Checking

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

8 Connecting rod bearing cap

• Note installation position

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

9 Oil spray jet

• For piston cooling

10 25 Nm

• Install without sealant

11 Connecting rod bolt 30 Nm + 90° (1/4 additional turn)

• Replace

• Lubricate threads and contact surface

• Use old bolt to measure radial play

Installed Position of Piston and Piston/Cylinder Allocation





Pistons in cylinder 1 and 2:

Large valve pocket for intake valve toward flywheel side - arrows -

Pistons in cylinder 3 and 4:

Large valve pocket for intake valve toward belt pulley side - arrows -

• On new pistons, the cylinder allocation is stamped on the piston face in paint.

• Pistons for cylinder 1 and 2: identification 1/2

• Pistons for cylinder 3 and 4: identification 3/4