Connecting Rod: Service and Repair

Pistons and Connecting Rod Assembly Overview

• Oil injector jet for piston cooling.





1 Bolts

• Replace

• Lubricate the threads and contact surface

• 40 Nm plus an additional 120° turn

2 Connecting Rod Bearing Cap

• Mark for installation later

• Mark affiliation to cylinder with paint

• Installation position of connecting rod pairs

3 Fitting Pin

• 2 pieces

• Make the connecting rod bearing cap fits securely

4 Bearing Shells

• Check that retaining tabs are secured

• Replace any worn bearing shells

• Oversized bearings are available for reworked crankshaft connecting rod journals

5 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 => [ Connecting Rod, Measuring Radial Clearance ] Testing and Inspection

6 Circlip

• Replace

7 Piston Pin

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

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

8 Piston

• Mark the installation position and cylinder allocation

• Checking

• Measuring cylinder bore

• Piston and cylinder dimensions, refer to => [ Piston and Cylinder Dimensions ] [1][2]Piston, Engine

• Install with piston ring compressor

9 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

Measuring the Piston Ring Gap

- Push the piston ring squarely from above down to approximately 15 mm from the bottom end of the cylinder.





- Use a piston without a piston ring for sliding in.





Measuring the Ring to Groove Clearance

- Clean the piston ring groove before checking.









Pistons, Checking

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





• Maximum deviation from the specified 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 the specified dimension: 0.08 mm.

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

Piston Installed Position

CAUTION!
The coating on the piston crown could be destroyed.

• Mark the allocation to the cylinder on the piston crown with paint to install used pistons. Do not mark the piston head with a punch, notch or something similar.

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 the connecting rods as a set.

- Mark the connecting rod and connector rod bearing caps to each other and to the cylinder - arrow - with paint for installation.





Connecting Rod Installation Position

• The molded tabs - arrows - on the beveled surface of the connecting rod pairs 1 and 2, 3 and 4, 5 and 6, 7 and 8 as well as 9 and 10 must face each other.





Oil Spray Jet for Piston Cooling





1. Oil spray jet

2. Insert the bolt with locking compound. Tighten to 9 Nm.

• Do not bend the oil injector jets.

• Bent oil injector jets must be replaced.