Overhaul

Pistons and connecting rods, disassembling and assembling

Note: Refer to Oil injector jet for piston cooling.





1 - Connecting rod bolt, 30 Nm plus an additional 90 ° (1/4 turn)
^ Always replace
^ Grease thread and contact surface
^ Tighten to 30 Nm when measuring radial clearance, but do not turn further

2 - Connecting rod bearing cap
^ Do not interchange
^ Mark allocation to cylinder using a color marker -B-.
^ Observe when installing bearing cap: Tabs at contact surfaces at face of connecting rod must be aligned -A-

3 - Bearing shell
^ Note installed position
^ Do not interchange run-in connecting rod bearing shells (mark)
^ Refer to Measuring radial play
^ Tighten bolts item -1- to 30 Nm when measuring radial clearance, but do not turn further

4 - Connecting rod
^ Replace only as a set
^ Mark allocation to cylinder using a color marker -B-
^ Observe when installing bearing cap: Tabs at contact surfaces at face of connecting rod must be aligned -A-

5 - Snap ring

6 - Piston pins
^ In case of difficulty of movement, warm piston to approx. 60 ° C
^ When removing and installing, use VW222a Pilot drift

7 - Pistons
^ Arrow on piston head points to belt pulley side

8 - Piston rings
^ Offset gaps by 120 °
^ Use piston ring pliers to remove and install
^ Marking or identification "TOP" i.e. marked side must face toward piston head





Fig. 1 Checking piston ring end gap

- Insert ring at right angle to cylinder wall from above to lower cylinder opening approx. 15 mm from cylinder edge. Use piston without rings to insert.








Fig. 2 Checking piston ring side clearance

- Before measuring, clean piston ring groove








Fig. 3 Checking pistons

Special tools and equipment
^ External micrometer 75-100 mm

- Measure approx. 10 mm from lower edge, at a 90 ° angle to piston pin axis.

^ Deviation from nominal dimension: max. 0.04 mm

Refer to Specified dimension; piston and cylinder measurements





Fig. 4 Checking cylinder bore

Special tools and equipment
^ Inner bore gauge 50-100 mm

- Measure diagonally at 3 positions, horizontally -A- and lengthwise -B-.

^ Deviation from nominal dimension: max. 0.08 mm

Refer to Specified dimension; piston and cylinder measurements





Fig. 5 Piston installed position and application piston/cylinder

- Mark installed position and allocation to cylinder on piston head using chalk or waterproof felt pen.

Note: Do not use a center punch or scribe, since the piston head coating will be damaged.

^ Installed position:

Arrow on piston head points to belt pulley side





Fig. 6 Marking connecting rods

Note:
^ Replace the connecting rods only as a set.
^ Do not interchange the connecting rod bearings.

- Before removing, mark allocation of connecting rod and connecting rod bearing caps to each other and to cylinder using a color marker (arrow).





Fig. 7 Installed position of connecting rods

^ Molded tabs (arrows) at the bevelled surfaces of the connecting rod pairs 1 and 2, 3 and 4 as well as 5 and 6 must point toward each other.





Fig. 8 Oil injector jet for piston cooling

1 - Bolt, 10 Nm

2 - Oil injector jet for piston cooling