Connecting Rod: Service and Repair

Pistons And Connecting Rods, Disassembling And Assembling
1. Piston ring
^ Offset ring gaps 120°
^ Remove and install using piston ring pliers
^ "TOP" faces towards crown
^ Ring gap, checking: go to Fig. 1
^ Ring to groove clearance checking: go to Fig. 2
2. Piston
^ Mark installation position and cylinder number
^ Arrow on piston crown points to: pulley end
^ Install using piston ring tool
^ If any cracks on piston skirt, replace piston
^ Piston projection at TDC, checking, Refer to Piston, Engine, Testing and Inspection
3. Piston pin
^ If difficult to remove, heat piston to 60°C
^ Remove and install using VW222A
4. Circlip
5. Connecting rod
^ Only replace as a set
^ Mark cylinder number -A-
^ Installed position: Marking -B- faces pulley end
6. Fitted pin
^ Pin must seat securely in connecting rod, not in bearing cap
7. Bearing shell
^ Note installed position
^ Do not interchange used bearing shells
^ Make sure retaining lugs fit tightly in recesses
^ Axial clearance Wear limit: 0. 37 mm
^ Check radial clearance with Plastigage: Wear limit: 0. 08 mm Do not rotate crankshaft while checking.
8. Cylinder block
^ Checking cylinder bores go to Fig 3
^ Piston and cylinder dimensions, Refer to Piston, Engine, Specifications
9. Connecting rod bearing cap
^ Note installed position
10. Oil spray jet
^ For piston cooling
11. 25 Nm (18 ft. lbs.)
^ Install without sealant
12. Connecting rod bolt
^ 30 Nm (22 ft. lbs.) plus additional 1/4 turn (90°)
^ Always replace
^ Oil the threads and contact surfaces
^ Use old bolts to measure radial clearance





Fig. 1 Piston ring gap, checking





- Squarely insert ring into top of cylinder and push it down to approximately 15 mm from lower edge of cylinder.





Fig. 2 Ring to groove clearance, checking





Clean groove before checking.





Fig. 3 Cylinder bores, checking

Special tools and equipment
^ Internal dial gauge 50 to 100 mm

- Take measurements at 3 positions in both lateral -A- and longitudinal -B- directions, as illustrated.

^ deviation from nominal dimension: 010 mm maximum

Note: Do NOT measure the cylinder bores when the block is mounted on a repair stand using the VW540 adaptor bracket. Bending stresses resulting from the mass overhang will make incorrect measurements likely.





Fig. 4 Piston installation position and piston/cylinder allocation
Piston in cylinders 1 and 2:
Larger intake valve chamber points toward flywheel (arrows)
Piston in cylinders 3 and 4:
Larger intake valve chamber points toward belt pulley side (arrows).

Note: New piston/cylinder allocations are shown by a colored mark on the piston crown.

^ Piston for cylinder 1 and 2: marked 1/2
^ Piston for cylinder 3 and 4: marked 3/4