Piston: Service and Repair

1. Piston ring
- Offset gaps by 120°
- Remove and install with piston ring pliers
^ "TOP" faces towards piston crown
^ Ring gap, checking refer to Fig. 1
^ Ring to groove clearance, checking refer to Fig. 2
2. Piston
^ Installation position and allocation of piston/cylinder refer to Fig. 4
- Install using piston ring clamp
^ If any cracks found on piston skirt, replace piston
^ Piston projection at TDC, check.
3. Piston pin
^ If difficult to remove, heat piston to 60°C (140°F)
^ Remove and install using VW 222a
4. Circlip
5. Connecting Rod
- Only replace as a set
- Mark cylinder number -A-
^ Installation position:
Marking -8- faces pulley end
6. Bearing shell
^ Note installation position
^ Do not interchange used bearing shells
^ Ensure retaining lugs fit tightly in recesses
^ Axial clearance Wear limit: 0.37 mm
^ Check radial clearance using Plastigage (R):
Wear limit: 0.08 mm
Do not rotate crankshaft when checking radial clearance
7. Cylinder block
^ Cylinder bores, checking refer to Fig. 3
^ Piston and cylinder dimensions
8. Connecting Rod bearing cap
- Note installation position
9. Locating pin
^ Pin must seat securely in Connecting Rod, not in bearing cap
10. Oil spray jet
^ For piston cooling
11. 10 Nm (7 ft. lbs.)
- Install with AMV 188 100 02
12. Connecting Rod bolt, 30 Nm (22 ft. lbs.) + 1/4 turn (90°) further
- Replace
- Oil threads and contact surfaces
- Use, old bolts to measure radial clearance








Fig. 1 Piston ring gap, checking
- Push ring squarely from above down to approx. 15 mm from bottom end of cylinder.








Fig. 2 Checking ring to groove clearance
Clean groove before check.





Fig. 3 Cylinder bores, checking

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required
^ Inside dial gauge 50 to 100 mm
- Take measurements at 3 positions in both lateral -A- and longitudinal direction -B-, as illustrated.
^ Deviation from nominal dimension: 0.10 mm maximum

Note: Do NOT measure cylinder bore diameters when the cylinder block is mounted on an engine stand via the VW 540 adapter bracket, incorrect measurements could result.





Fig. 4 Piston/cylinder allocation installation position
Piston in cylinders 1 and 2:
Larger intake valve chamber towards flywheel -arrows-
Piston in cylinders 3 and 4:
Larger intake valve chamber towards belt pulley side -arrows-.

Note: New piston allocation to cylinders is 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