Connecting Rod: Service and Repair

Pistons and connecting rods, disassembling and assembling





1. 30 Nm + 1/4 turn (90°) further
^ Replace connecting rod bolt -13-
^ Oil threads and contact surface
^ To measure radial clearance, tighten to 30 Nm but not further

2. Pressure relief valve, 27 Nm
^ Opens at: 2.5...3.2 bar

3. Oil spray jet
^ For piston cooling





4. Connecting rod bearing cap
^ Mark cylinder number -B-
^ Installed position: Marking -A- must face toward pulley end

5. Bearing shell
^ Note installed position
^ Do not interchange used bearing shells (mark)
^ Make sure that bearing shell is seated correctly in retaining lugs
^ 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
^ To measure radial clearance, tighten nut -1- to 30 Nm but not further





6. Cylinder block
^ Checking cylinder bore
^ Piston and cylinder dimensions

7. Bearing shell
^ With oil drilling for piston pin lubrication
^ Note installed position
^ Do not interchange used bearing shells (mark)
^ 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
^ To measure radial clearance, tighten nut -1- to 30 Nm but not further





8. Connecting rod
^ Only replace as set
^ Mark cylinder number -B-Installed position: Marking -A- must face toward pulley end
^ With oil drilling for piston pin lubrication

9. Circlip
10. Piston pin
^ If difficult to move, heat piston to approximately 60°C
^ Remove and install with VW 222a





11. Piston rings
^ Offset gaps by 120°
^ Remove and install with piston ring pliers
^ TOP must face toward piston crown
^ Checking ring gap Fig. 1
^ Checking ring to groove clearance Fig. 2

12. Piston
^ Checking Fig. 3
^ Mark installed position and cylinder number
^ Arrow on piston crown must point to pulley end
^ Install using piston ring clamp

13. Connecting rod bolt
^ Replace






Fig. 1 Checking piston ring gap
- Push ring squarely from above down to lower cylinder bore, approximately 15 mm from cylinder edge. 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 lower edge of skirt, at 90° to piston pin axis.
^ Deviation from nominal dimension: max. 0.04 mm





Fig. 4 Checking cylinder bore

Special tools and repair equipment required
^ Internal dial gauge 50...100 mm
- Take measurements at 3 positions in both lateral -A- and longitudinal -B- directions.
^ Deviation from nominal dimension: max. 0.08 mm