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	“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	Fitting position and piston/cylinder correspondence → Fig.

q	Arrow on piston crown points to pulley end

q	Install using piston ring clamp

q	If the piston pin is cracked, replace the piston

q	Check position at TDC → Chapter

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 correspondence of cylinder -A- with a coloured pencil

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

6 -

Pin

q	The pins should house firmly in the bearing and not in the cap

7 -	Halfshell bearing

q	Note the fitting position.

q	Do not interchange used bearing shells

q	Observe right positioning onto attachment flanges

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

8 -	Cylinder block

q	Checking cylinder bores → Fig.

q	Piston and cylinder dimensions → Chapter

9 -	Conrod bearing caps

q	Note the fitting position.

10 -	Oil spray jet

q	For piston cooling

11 -

25 Nm

q	Fit without sealer

12 -	Conrod bolt,

q	30 Nm + 1/4 turn (90 °)

q

Renew

q	Oil threads and contact surface

q	To measure the radial play used the old bolt

Checking piston ring play Special tools and workshop equipment required t  Feeler gauge Checking process –  Push ring squarely from above down to approx. 15 mm from bottom end of cylinder. 15 mm from the edge of the cylinder.

Piston ring Dimensions in mm	New	Wear limit
1st Compression ring	0,25...0,40	1,0
2st 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 Checking process Clean groove before checking.

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 bore diameters Special tools and workshop equipment required t  Internal dial gauge 50...100 mm Checking process –  Take measurements at right angles -A- and -B- at 3 positions. Deviation from specification 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 -Ar-2204A-, as incorrect measurements would then be possible.

Assembly position of pistons and piston/cylinder correspondence Pistons in cylinders 1 and 2: Large cut-out for inlet valve facing towards the flywheel -arrows- Pistons in cylinders 3 and 4: Large cut-out for inlet valve facing towards the pulley -arrows-   Note! t  New pistons have the numbers of the corresponding cylinders stamped on the crown. t  Pistons for cylinders 1 and 2: Numbers ½ t  Pistons for cylinders 3 and 4: Numbers ¾