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 spiral-type expander 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	The caps only fit in one position and only on the appropriate con-rod, this is due to the breaking procedure (cracking) separating the cap from the con-rod

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

q

Renew

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 angle which must be turned further can be measured with protractor -T20030-

9 -	Bearing shell

q	Do not interchange used bearing shells

q	Insert bearing shells centrally

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

10 -	Cylinder block

q	Checking cylinder bores → Fig.

q	Piston and cylinder dimensions → Chapter

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

Piston ring	Wear limit
Compression rings	1.0 mm
Oil scraper ring	1.0 mm

Checking ring to groove clearance Clean groove before check.

Piston ring	Wear limit
Compression rings	0.15 mm
Oil scraper ring	0.15 mm

Checking piston Special tools and workshop equipment required t  External 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; Piston and cylinder dimensions

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; Piston and cylinder dimensions   Note! The cylinder block bore must not be measured with the engine secured in engine mounting bracket AR-2204A using engine brackets -T20082-, as there is a possibility that the measurements will be falsified.