Volkswagen Workshop Service and Repair Manuals

Assembly overview - pistons and conrods

1 -	Piston rings

q	Offset gaps by 120°.

q	Remove and install using piston ring pliers.

q	“TOP” faces towards piston crown.

q	Checking ring gap → Fig..

q	Checking ring-to-groove clearance → Fig..

2 -

Piston

q	With combustion chamber.

q	Mark installation position and cylinder number.

q	Installation position and allocation of piston to cylinder → Fig..

q	Arrow on piston crown points to pulley end.

q	Install using piston ring clamp.

q	Cracks on piston skirt, renew piston

q	Checking piston projection at TDC → Chapter.

3 -	Piston pin

q	If difficult to remove, heat piston to 60 °C.

q	Remove and install with drift -VW 222-.

4 -

Circlip

5 -

Conrod

q	Mark cylinder allocation -A- with coloured pen.

q	Installation position: Marking -B- faces towards pulley end.

q	With industrially cracked bearing caps.

6 -	Bearing shell

q	Note installation position.

q	Do not interchange used bearing shells.

q	Insert bearing shells centrally.

q	Check for secure seating.

q	Axial clearance wear limit: 0.37 mm.

q	Check radial clearance with Plastigage: Wear limit: 0.08 mm, do not rotate crankshaft when checking radial clearance.

7 -	Cylinder block

q	Checking cylinder bores → Fig..

q	Piston and cylinder dimensions → Chapter.

8 -	Conrod bearing cap

q	Note installation position.

q	Caps fit only in one position and only on the corresponding con-rod due to breaking procedure (cracking) for separating cap from con-rod.

9 -	Oil spray jet

q	For piston cooling.

10 -

25 Nm

q	Insert without sealant.

11 -	Conrod bolt, 30 Nm + 1/4 turn (90°) further

q

Renew.

q	Oil threads and contact surface.

q	Use old bolts to measure radial clearance.

Checking piston ring gap Special tools and workshop equipment required t  Feeler gauges –  Push piston ring squarely from above down to approx. 15 mm from bottom end of cylinder.

Piston ring Dimensions in mm	New	Wear limit
1st compression ring	0.20...0.40	1.0
2nd compression ring	0.20:..0.40	1.0
Oil scraper ring	0.25...0.50	1.0

Checking ring-to-groove clearance Special tools and workshop equipment required t  Feeler gauges –  Clean ring groove before checking.

Piston ring Dimensions in mm	New	Wear limit
1st compression ring	0.06...0.09	0.25
2nd compression ring	0.05...0.08	0.25
Oil scraper ring	0.03...0.06	0.15

Checking cylinder bores Special tools and workshop equipment required t  Internal dial gauge 50...100 mm –  Take measurements at 3 positions in both transverse -A- and longitudinal -B- directions, as illustrated. Difference between actual and nominal diameter: not more than 0.10 mm.   Note Cylinder bores must not be measured when cylinder block is mounted on a repair stand with engine support bracket -VW 540-, as measurements may then be incorrect.

Piston installation position and allocation of piston to cylinder. Piston in cylinders 1 and 2: Larger inlet valve chamber -arrows- towards flywheel. Piston in cylinders 3 and 4: Larger inlet valve chamber towards belt pulley side -arrows-.   Note t  New piston allocation to cylinders is shown by a coloured marking on piston crown. t  Piston for cylinders 1 and 2: marked 1/2 t  Piston for cylinders 3 and 4: marked 3/4