SEAT Workshop Service and Repair Manuals

Dismantling and assembling pistons and conrods

1 -

Circlip

2 -	Piston pin

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

q	Remove and install with drift -T20019-

3 -

Piston

q	Checking → Fig.

q	Mark installation position and cylinder number

q	Arrow on piston crown points to pulley end

q	Install using piston ring clamp

4 -	Compression rings

q	Offset gaps by 120°

q	Remove and install compression rings with piston ring pliers

q	“TOP” faces towards piston crown

q	Checking ring gap → Fig.

q	Checking ring to groove clearance → Fig.

5 -	Oil scraper ring

q	Remove and install 2-part oil scraper rings carefully by hand

q	“TOP” faces towards piston crown

q	Checking ring gap → Fig.

q	Checking ring to groove clearance → Fig.

6 -

Conrod

q	Only renew as a set

q	Mark cylinder number -A-

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

q	Guided axially via piston

7 -	Conrod bearing cap

q	Note installation position

q	Link rods split through cracking may only be placed in one position and only with the proper link rod

8 -	Conrod bolt, 20 Nm + 1/4 turn (90°) further

q

Renewing

q	Oil threads and contact surface

q	To measure radial clearance tighten to 20 Nm but not further

q	The turning further can be done in several stages

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

9 -	Aluminium cylinder block

q	Checking cylinder bores → Fig.

q	Piston and cylinder dimensions → Chapter

10 -	Bearing shell

q	Do not interchange used bearing shells

q	Insert bearing shells in the centre

q	Check radial clearance with Plastigage: New: 0.020...0.061 mm Wear limit: 0.091 mm Do not rotate crankshaft when checking radial clearance

Checking piston ring gap –  Push ring squarely from above down to approx. 15 mm from bottom end of cylinder.

Piston segment	Wear limit
for compression	1.0 mm
oil scraper	1.0 mm

Checking ring to groove clearance Clean groove before check

Piston segment	Wear limit
Kompressionsring	0.15
Ölabstreifring	0.15

Checking piston Special tools and workshop equipment required t  Outside micrometer 60...90 mm –  Approx. 10 mm from lower edge and offset 90° to piston pin axis. Deviations from nominal dimensions max. 0.04 mm. Nominal dimension → Chapter.

Checking cylinder bores Special tools and workshop equipment required t  Internal dial gauge 50...100 mm –  Take measurements at 3 positions in both lateral -A- and longitudinal -B- directions, as illustrated. Deviation from nominal dimension max. 0.08 mm. Nominal dimension → Chapter.   Note! Measuring the cylinder bores must not be done when the cylinder block is mounted on repair stand AR-2204A with assembly bracket -T20082-, as incorrect measurements would then be possible.