Connecting Rod: Service and Repair

Pistons and Connecting Rod Assembly Overview

• Oil injector jet for piston cooling.





1 Connecting Rod Bolt

• Replace

• 50 Nm plus an additional 90° turn

• Lubricate the threads and contact surface

2 Connecting Rod Bearing Cap

• Do not interchange

• Mark affiliation to cylinder with paint

• Installation position of connecting rod pairs

3 Bearing Shells

• Check that retaining tabs are secured

• Mark used bearing shells for reinstallation but not on the running surface

• Replace the bearing shells worn down to the base layer

• Oversized bearings are available for reworked crankshaft connecting rod journals

4 Connecting Rod

• Only replace as set

• Mark affiliation to cylinder with paint

• Installation position of connecting rod pairs

• Axial play for each new connecting rod pair: 0.20 to 0.38 mm

• Radial clearance, measuring, refer to => [ Connecting Rod, Measuring Radial Clearance ] Connecting Rod, Measuring Radial Clearance

5 Piston Pin

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

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

6 Circlip

• Replace

7 Piston

• Installation position of pistons

• Piston and cylinder dimension, piston allocation to cylinder bore, refer to => [ Piston and Cylinder Dimensions ] [1][2]Piston, Engine

• Checking

• Install with piston ring compressor

• Measuring cylinder bore

8 Piston Rings

• Offset gaps by 120°

• Use piston ring pliers for removal and installation

• "TOP" marking or inscribed side must point to piston head

• Gap, measuring

• Measuring side clearance

Piston Ring End Gap, Measuring





- Slide piston ring down from above at a right angle to cylinder wall until it is approximately 15 mm from bottom edge of cylinder.

- When sliding in, use a piston without piston rings.





Measuring Piston Ring Side Clearance





- Clean the ring groove of piston before checking.





Pistons, Checking





- Measure approximately 15 mm from the lower edge at a 90° angle to the piston pin axis using an external micrometer 75 to 100 mm.

• Maximum deviation from nominal dimension: 0.03 mm.

Nominal dimension, refer to => [ Piston and Cylinder Dimensions ] [1][2]Piston, Engine.

Measuring Cylinder Bore





- Measure diagonally at 3 positions transversely - A - and longitudinally - B - using a cylinder gauge (VAS 6078).

• Maximum deviation from nominal dimension: 0.08 mm.

Nominal dimension, refer to => [ Piston and Cylinder Dimensions ] [1][2]Piston, Engine.

Piston Installation Position

- Identify allocation to cylinder with paint on piston crown.

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

Installation position:

• Arrows on piston heads point to belt pulley side.

• Large valve recesses - 1 - point toward center of engine.





Mark Connecting Rod





• Only replace connecting rod as a set.

• Do not interchange connecting rod bearings.

- Before removing, mark allocation of connecting rod and connecting rod bearing caps to each other and to cylinder with paint - arrow -.

Connecting Rod, Installed Location





• Molded tabs - arrows - at the beveled surfaces of the connecting rod pairs 1 and 2, 3 and 4, 5 and 6, 7 and 8 as well as 9 and 10 must point toward each other.

Oil Spray Jet For Piston Cooling





1. Oil spray jet

2. Bolts - 9 Nm. Insert with locking compound.

CAUTION!
• Do not bend the oil injector jets.

• Bent oil injector jets must be replaced.