SEAT Workshop Service and Repair Manuals

Piston and piston rod: removal and refitting

1 -	Piston segment

q	Descale the cuts by 120°

q	Remove and refit using segment pliers

q	The label “TOP” must point at the piston head

q	Check the gap between the ends of the segments → Fig.

q	Check the coupling play between the segments and the grooves of the piston → Fig.

2 -

Piston

q	With combustion chamber

q	Mark the assembly position and the correspondence with the respective cylinder

q	Assembly position and piston/cylnder correspondence → Fig.

q	The arrow of the piston head must point at the pulley

q	Fit using segment assembly shirt

q	Should the piston stem become cracked, replace the piston

q	Check the position of the piston on TDC → Chapter

3 -	Piston pin

q	If the movement is heavy, heat the piston to 60 °C

q	Remove and refit using the -T20019-

4 -	Safety washer

5 -

Rod

q	Only replace as a unit

q	Mark the correspondence with cylinder -A-

q	Assembly position: The marks -B- must point at the pulley

6 -

Pin

q	The pins must be firmly fitted in the rod, not in the cap

7 -	Semibearing

q	Note the version

q	Note the fitting position

q	Do not swap worn semibearings

q	Note the correct position on the fixing lips

q	Axial play

Wear limit: 0.37 mm

q	Measure the radial play with Plastigage:

Wear limit: 0.08 mm

Do not turn the crankshaft when measuring the radial play

8 -	Engine block

q	Check the diameter of the cylinders → Fig.

q	Piston and cylinder measurements → Chapter

9 -

Rod caps

q	Note the fitting position

10 -	Oil injector

q	To cool the pistons

11 -

25 Nm

q	Fit without sealant

12 -	Rod bolt, 30 Nm + 1/4 turn (90°)

q

Replace

q	Lubricate the thread and the support surface

q	Use the worn bolt to measure the radial play

Checking the gap between the ends of the piston segments –  Fit the segment from the top in such a way that it is in a right angle in the lower opening of the cylinder, with an approx. separation of 15 mm from the edge of the cylinder.

Piston segment Measurements in mm	New	Wearlimit
1stcompression segment	0.20 … 0.40	1.0
2nd compression segment	0.20 … 0.40	1.0
Oil scraper segm.	0.25 … 0.50	1.0

Check the coupling play between the segments and the piston grooves Clean between the housing grooves of the pistons.

Piston segment Measurements in mm	New	Wearlimit
1stcompression segment	0.06 … 0.09	0.25
2nd compression segment	0.05 … 0.08	0.25
Oil scraper segm.	0.03 … 0.06	0.15

Checking the diameter of the cylinders Special tools and workshop equipment required t  Interior calliper 50 … 100 mm –  Cross measure three different points in a transversal -A- and longitudinal -B- direction.    Difference over nominal measurement 0.10 mm max.   Note! The measurement of the interior diameter of the cylinder should not be taken when the engine block is fixed to the assembly jack by the engine support-AR-2204A- as such measurements might be incorrect.

Assembly position of pistons and piston/cylinder correspondence Pistons in cylinders 1 and 2: Large box for intake valve to the flywheel -arrows-. Pistons in cylinders 3 and 4: Large box for intake valve to the pulley -arrows-.   Note! t  New pistons bear the numbering of the corresponding cylinders marked in colour on the piston head. t  Pistons for cylinder s1 and 2: Numbering 1/2 t  Pistons for cylinders 3 and 4: Numbering 3/4