Piston: Service and Repair

Piston and Connecting Rod Assembly Overview





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

• Replace

• Lubricate threads and contact surface

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

2 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

• 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.

• Affiliation to the cylinder mark - B -

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

5 Bearing shell

• Note installation position => [ Bearing Shells, 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:

New: 0,02 to 0,06 mm

Wear limit: 0,09 mm

Do not turn crankshaft when measuring radial play.

6 Connecting rod

• With cracked bearing cap

• Separate new connecting rod => [ New Connecting Rod, Separating ] Procedures

• only replace as set

• Affiliation to the cylinder mark - B -

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

7 Circlip

8 Piston pin

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

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

9 Piston

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

• Mark installed position and cylinder allocation

• Arrow on piston face points toward belt pulley side

• Install with piston ring compressor

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

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

10 Piston rings

• Offset gaps by 120°

• use piston ring pliers for removal and installation

• Markings face toward piston crown

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

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

Bearing Shells, Installation Location





Bearing shell - 1 - with oil bore - arrow - for connecting rod.

Bearing shell - 2 - without oil bore for connecting rod cover.

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

Dimension - a - must be the same at left and right.