SEAT Workshop Service and Repair Manuals

Piston and piston rod: dismantling and assembling

1 -	Piston rings

q	Displace gaps120º

q	Remove and install with piston ring pliers.

q	The labelling “TOP” must face towards the piston crown

q	Checking end clearance → Fig.

q	Checking piston ring side clearance → Fig.

q	2 or 3 part oil scraper ring, mixed installations permissible

2 -

Piston

q	Testing → Fig.

q	Mark installation position and respective cylinder

q	Arrow on piston crown faces pulley end

q	Install using piston ring installation sleeve

3 -	Piston pin

q	If it is difficult to attach the spring pin, heat the piston to 60 ºC

q	Removing and fitting with thetappet -T20019-

4 -	Securing ring

5 -

Conrod

q	Renew as set only.

q	Mark cylinder correspondence -B-

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

6 -	Half bearing

q	Note installation position

q	Do not interchange used bearing shells

q	Ensure retaining lugs fit tightly in recesses.

q	New axial play: 0,05 ... 0.31 mm Wear limit: 0.37 mm

q	Check the radial play using a Plastigage: New: 0,01 ... 0.06 mm Wear limit: 0.09 mm When measuring the radial play, do not rotate the crankshaft

7 -	Cylinder block

q	Check cylinder bore → Fig.

q	Piston and cylinder measurements → Chapter

8 -	Conrod bearing caps

q	Note installation position

9 -	Oil spray jet

q	for piston cooling

10 -	Pressure relief valve, 27 Nm

q	Opening pressure: 1,3 ... 1.6 bar

11 -	30 Nm + 1/4 vuelta (90°)

q

Replace

q	Oil threads and contact surface.

q	To measure radial play, tighten to 30 Nm, without retightening

Fitted position in the half bearings Bearing shell -1- with oil hole -arrow- for conrod. Bearing shell -2- without oil hole for conrod bearing cap. –  Centre the conrod bearings and the conrod bearing caps. The measurement -a- must be the same to the right and to the left.

Piston ring ends: check gap Special tools and workshop equipment required t  Gauge –  Insert ring at right angles from above into lower cylinder opening from of approx. 15 mm from the edge of the cylinder.

Piston ring		Clearance between ends
		New	Wear limit
Compression rings	mm	0,20 ... 0,40	0,8
Oil scraper ring	mm	0,25 ... 0,50	0,8

Checking piston ring side clearance checking Special tools and workshop equipment required t  Gauge First clean piston ring housing groove.

Piston ring		Clearance
		New	Wear limit
Compression rings	mm	0,06 ... 0,09	0,20
Oil scraper ring	mm	0,03 ... 0,06	0,15

Pistons: checking Special tools and workshop equipment required t  Outer micrometer 75... 100 mm Measure to approx. 10 mm from the lower edge, perpendicular to the shaft of the spring pin. Tolerance with respect to max. nominal measurement 0.04 mm.

Bore: checking Special tools and workshop equipment required t  Interior bore 50 ... 100 mm –  Take measurements at 3 positions in both lateral -A- and longitudinal -B-. Tolerance with respect to max. nominal measurement 0.08 mm.   Note Measuring the cylinder bores must not be done when the cylinder block is mounted on a engine bracket -T20172/3- and tower -T20172/2-as incorrect measurements would then be possible.