Connecting Rod: Service and Repair

Pistons and connecting rods, disassembling and assembling





Notes: When working on the engine it should be secured to engine stand with engine bracket VW 540.

1 - Piston ring
^ Offset gaps by 120°
^ Remove and install with piston ring pliers
^ "TOP" faces toward piston crown
^ Checking ring gap, refer to Fig. 1
^ Checking ring to groove clearance, Refer to Fig. 2
2 - Piston
^ Checking, Refer to Fig. 3
^ Mark installation position in relation to connecting rod and cylinder number with a permanent felt - marker.
- Arrow on piston crown points to pulley end
- Install using piston ring clamp
- Refer to Piston and cylinder dimensions.
3 - Connecting rod
^ Only replace as a set
^ Mark cylinder number - B - .
- Installation position: Marks - A - must be aligned and facing belt pulley side
- With hole for lubricating piston pin
4 - Connecting rod bearing cap
^ - Mark cylinder number - B -.
- Installation position: Marks - A - must be aligned and facing belt pulley side
5 - 30 Nm + 1/4 turn (90°) further
^ Replace
^ Oil threads and contact surface
^ To measure radial clearance tighten to 30 Nm, but not further
6 - Pressure relief valve, 27 Nm
^ Opens at 2.5 - 3.2 bar
^ Do not apply sealant when installing
7 - Oil spray jet
^ For piston cooling
8 - Bearing shell
^ Note installation position
^ Do not interchange used bearing shells (mark)
^ Ensure retaining lugs fit tightly in recesses
^ Axial clearance:
- New: 0.10 - 0.35 mm
- Wear limit: 0.40 mm
^ Check radial clearance with Plastigage:
- New: 0.01 - 0.05 mm
- Wear limit: 0.12 mm
^ Do not rotate crankshaft when checking radial clearance
^ With hole for lubricating piston pin
9 - Cylinder block
^ Checking cylinder bores Fig. 4
^ Refer to Piston and cylinder dimensions.
10 - Connecting rod bolt
^ Replace together with item - 5
11 - Circlip
12 - Piston pin
^ If difficult to move, heat piston to approximately 60°C.
^ Remove and install with drift VW 222a







Fig. 1 Checking piston ring gap
^ Push ring squarely from above down to approximately 15 mm from bottom end of cylinder. To do this use a piston without rings.








Fig. 2 Checking ring to groove clearance

^ Clean groove before checking clearance.





Fig. 3 Checking piston
^ Measure pistons approximately 10 mm from the lower edge of skirt, at 90° to the piston pin axis.
^ Permissible deviation from nominal dimension: maximum 0.04 mm





Fig. 4 Checking cylinder bores
^ Use internal dial gauge (50 - 100 mm).
^ Take measurements at 3 positions in both lateral direction - A - and longitudinal direction - B - .
^ Permissible deviation from nominal dimension: maximum 0.10 mm

Notes: Measuring the cylinder bores must not be done when the cylinder block is mounted on a repair stand with adapter bracket VW 540, as incorrect measurements would then be possible.





Piston and cylinder, dimensions