SEAT Workshop Service and Repair Manuals

Dismantling and assembling pistons and conrods

1 -	Piston ring

q	Offset gaps by 120 °

q	Remove and install with 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	Mark installation position and allocation piston/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 punch -U-20008-

4 -

Circlip

5 -

Conrod

q	Only renew as a set

q	Mark cylinder number -A-

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

6 -	Bearing shell

q	Note installation position

q	Do not interchange used bearing shells

q	Ensure retaining lugs fit tightly in recesses

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

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

Renewing

q	Oil threads and contact surface

q	The quarter turn further can be done in several stages.

q	The turning further angle can be measured with protractor -T20030-

q	To measure radial clearance use old bolts

Checking piston ring gap Special tools and workshop equipment required t  Feeler gauge Test sequence –  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 gauge Test sequence Clean groove before check.

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 Test sequence –  Take measurements at 3 positions in both lateral -A- and longitudinal -B- directions, as illustrated. Deviation from nominal dimension max. 0.10 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 installation position and piston/cylinder allocation Piston in cylinders 1 and 2: Larger inlet valve chamber towards flywheel -arrows- 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 cylinder 1 and 2: marked 1/2 t  Piston for cylinder 3 and 4: marked 3/4