SEAT Workshop Service and Repair Manuals

Piston and conrod: dismantling and assembling

1 -	Piston rings

q	Offset gaps by 120 °

q	Remove and install with piston ring pliers

q	Carefully remove and install 3-part oil scraper rings by hand

q	“TOP” faces towards piston crown

q	Check ring gap → Fig.

q	Check ring to groove clearance → Fig.

2 -

Piston

q	Checking → Fig.

q	Mark installation position and piston/cylinder correspondence

q	Arrow on piston crown points to pulley end

q	Install using piston ring sleeve

3 -	Piston pin

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

q	Remove and install with -T20019-

4 -	Safety washer

5 -

Conrod

q	Only renew as a set

q	Mark cylinder number -A-

q	Assembly position: markings -B- should face towards the pulley end

q	Guided axially via piston

6 -	Bearing shells

q	Place bearing shells in correct position

q	Do not interchange used bearing shells

q	Measure pretension → Fig.

q	Check radial clearance with Plastigage:

New: 0,020…0,061 mm

Wear limit: 0,091 mm

Do not rotate the crankshaft when checking the radial clearance

7 -	Cylinder block

q	Checking cylinder bores → Fig.

q	Piston and cylinder dimensions → Chapter

8 -	Conrod bearing caps

q	Note the fitting position

q	The caps only fit in one position and only on the corresponding conrod, this is due to the breaking procedure (cracking) separating the cap from the conrod

9 -	Conrod bolt

q	M7: 20 Nm + 1/4 turn (90°)

q	M8: 30 Nm + 1/4 turn (90°)

q

Renew

q	Oil the threads and contact surface

q	To measure radial clearance tighten to 20 or 30 Nm but no further.

Checking ring gap –  Insert the ring from the top and push ring squarely from above down to approx. 15 mm from the edge of the cylinder.

Piston ring		Wear limit
Compression ring		1,0 mm
Oil scraper ring	1 part	1,0 mm
	3 parts	- → Note

1)  No wear limit details.

Checking ring to groove clearance –  Clean groove before checking.

Piston ring		Wear limit
Compression ring		0,15 mm
Oil scraper ring	1 part	0,15 mm
	3 parts	not measured

Checking pistons Special tools and workshop equipment required t  Micrometer 75…100 mm –  Measure approx. 10 mm from lower edge and offset 90 ° to piston pin axis. Deviations from nominal dimensions max. 0.04 mm

Checking cylinder bore diameters 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. Deviation from max. nominal dimension 0.08 mm   Note! Do not measure the cylinder bores when the cylinder block is mounted on a repair stand with adapter bracket -Ar-2204A-, as this could result in incorrect measurements.

Measuring bearing shell pretensio Special tools and workshop equipment required t  Depth gauge The bearing shell pretension is calculated as follows:

	dimension -a- of the bearing shell
-	conrod diameter -b-
=	Pretension

Minimum dimension: 1.5 mm If the pretension is not achieved: –  Renew bearing shells.