Piston and Conrod, Disassembling and Assembling

Piston and Conrod, disassembling and assembling
1- Piston rings
^ Offset gaps by 120°
^ Use piston ring pliers to remove and install
^ "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 and cylinder number her
^ Arrow on piston crown points to pulley end
^ Install using piston ring clamp
3- Floating piston pin
^ If difficult to remove, heat piston to 60°C
^ Remove and install with VW 222A
4- Snap ring
5- Conrod
^ With cracked bearing cap
^ Only replace as a set
^ Mark relationship to cylinder-B
^ Installation position: Marking -A- faces toward belt pulley end
6- Bearing shell
^ Observe installation position, Refer to Fig. 4
^ Insert bearing shells centrally
^ Do not interchange used bearing shells
^ Check seated securely
^ Axial clearance, New: 0.10...0.35 mm; Wear limit: 0.4 mm
^ Check radial clearance with Plastigage: New: 0.01...0.05 mm Wear limit: 0.09 mm; Do not rotate crankshaft when checking radial clearance
7- Cylinder block
^ Checking cylinder bore, Refer to Fig. 5
8- Conrod bearing cap
^ Observe installing position
^ Caps only fit in one position and only on appropriate conrod due to breaking procedure (industrially cracking) separating cap from conrod
9- 30 Nm 1/4 turn (90°) further
^ Torx E 10
^ Replace
^ Oil thread and contact surface
^ To measure radial clearance tighten to 30 Nm, but do not turn further





Fig. 1 Checking piston ring gap
Special tools, testers, measuring instruments and auxiliary items required





^ Feeler gauge

Test sequence





^ Push ring squarely from above down to approximately 15 mm from bottom end of cylinder.





Fig. 2 Checking ring to groove clearance
Special tools, testers, measuring instruments and auxiliary items
^ Feeler gauge
Test sequence





Clean groove before checking.





Fig. 3 Checking piston
Special tools, testers, measuring instruments and auxiliary items required
^ External micrometer 75...100 mm

Test sequence
^ Measure pistons approximately 10 mm from lower edge of skirt, 90° offset to axis of floating piston pin.
Deviation from nominal dimension: maximum 0.04 mm





Fig. 4 Installation position of bearing shells
Bearing shell -1- with oil channel (arrow) for conrod
Bearing shell -2- without oil channel conrod bearing cap
^ Insert bearing shells and conrod bearing cap centrally.
Dimension -a- must be same on both left and right sides





Fig. 5 Checking cylinder bores
Special tools, testers, measuring instruments and auxiliary items required
^ Internal dial gauge 50...100 mm
^ Measure bores at 3 locations in both directions -A- across engine and -B- in line with crankshaft.
Deviation from nominal dimension: maximum 0.08 mm

Note: 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 result.