SEAT 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	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	If piston skirt is cracked, 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 222A-.

4 -

Circlip

5 -

Conrod

q	Renew as set only.

q	Mark cylinder allocation -A- with coloured pen.

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

6 -	Bearing shell

q	Note installation position.

q	Note version: Upper bearing shell (towards piston) is made of a more wear resistant material. Identification: Black line on bearing surface in area of joint.

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.

q	Do not rotate crankshaft when checking radial clearance

7 -	Cylinder block

q	Checking cylinder bores → Fig..

q	Piston and cylinder dimensions → Chapter.

8 -	Bearing cap

q	Note installation position.

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 bolt for measuring radial clearance

Checking piston ring gap Special tools and workshop equipment required t  Feeler gauges –  Push 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 groove in piston before checking clearance.

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  Cylinder gauge 50...100 mm –  Take measurements at 3 positions in both lateral -A- and longitudinal -B- directions. 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 recess -arrows- towards flywheel. Piston in cylinders 3 and 4: Larger inlet valve recess -arrows- towards belt pulley end.   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