Pistons and Connecting Rods Disassembling and Assembling

Vehicles with engine codes: AWP, AWW





1-Piston ring
^ Offset gaps by 120
^ Remove and install with piston ring pliers
^ "TOP" faces towards piston crown
^ Checking ring gap = Fig. 1
^ Checking ring to groove clearance = Fig. 2
2-Piston
^ Checking = Fig. 3
^ Mark installation position and cylinder number
^ Arrow on piston crown points to pulley end
^ Install using piston ring clamp
3-Piston pin
^ If difficult to remove, heat piston to 60°C
^ Remove and install with VW 222a
4-Circlip
5-Connecting rod
^ Only replace as a set
^ Mark cylinder number-B
^ Installation position: Marking-A-faces towards pulley end
6-Bearing shell
^ Note installation position = Fig. 4
^ Do not interchange used bearing shells
^ Axial clearance New: 0.05 to 0.31 mm Wear limit: 0.37 mm
^ Check radial clearance with Plastigage: New: 0.01 to 0.06 mm Wear limit: 0.09 mm Do not rotate crankshaft when checking radial
7-Cylinder block
^ Checking cylinder bores = Fig 5
^ Piston and cylinder dimensions
8-Connecting rod bearing cap
^ Note installation position
9-Oil spray jet
^ For piston cooling
10-Pressure relief valve, 27 Nm
^ Opening pressure: 1.3 to 1.6 bar
11-Connecting rod bolt, 30 Nm + 1/4 turn (90°) further
^ Always replace
^ Oil threads and contact surface
^ To measure radial clearance use old bolts
^ To measure radial clearance tighten to 30 Nm but not further





Fig. 1 Checking piston ring gap
^ Special tools and equipment
^ Feeler gauges





- Push ring squarely from above down to approx. 15 mm from bottom end of cylinder.





Fig. 2 Checking ring to groove clearance
Special tools and equipment
^ Feeler gauges





- Clean groove before check.





Fig. 3 Checking piston
Special tools and equipment
^ Micrometer 75 to 100 mm

Measure pistons approx. 10 mm from the lower edge of skirt, at 90° to the piston pin axis.
Deviation from nominal dimension max. 0.04 mm





Fig. 4 Bearing shells-installation position
Bearing shell-1-for connecting rod (with hole-arrow-for oil channel).
Bearing shell-2-for bearing cap (without hole for oil channel).
- Insert bearing shell centered in connecting rod and bearing cap.
Dimension-a-must be the same on left and right. Max. deviation: 0.2 mm





Fig. 5 Checking cylinder bores
Special tools and equipment
^ Internal dial gauge 50 to 100 mm
^ Measure bores at 3 locations in both directions-A-across the engine and-B-in line with crankshaft.
^ Deviation from nominal dimension max. 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 be possible.





Piston and cylinder dimensions (engine codes AWP, AWW)