SEAT Workshop Service and Repair Manuals

Pistons and conrods - general over view of components t  Piston ring ends: check clearance → Fig. t  Checking ring-to-groove clearance → Fig.. t  Checking piston → Fig. t  Checking cylinder bores → Fig.. t  Half-bearing: installation position → Fig.

1 -	Conrod bolt, 30 Nm + 1/ further 4 turn (90°)

q

replace

q	Oil threads and contact surface.

q	To measure the radial play, use used bolts

q	To measure radial clearance, tighten to 30 Nm but do not turn further

2 -	Bolt with pressure relief valve, 27 Nm

q	Opening pressure 1.3 ... 1.6 bar.

3 -	Oil spray jet

q	For cooling the piston

4 -	Conrod bearing cap

q	Mark cylinder number -B-

q	Fitting position: The marks -A- should point towards the pulley

5 -	Bearing shells

q	Upper bearing shell with a drilled hole for lubricating the piston pin

q	Installation position → Fig.

q	Do not interchange used bearing shells (mark).

q	New axial play: 0.10 ... 0.35 mm. Wear limit: 0.40 mm

q	Recheck the radial play using a Plastigage New: 0.02 ... 0.06 mm. Wear limit: 0.09 mm do not rotate the crankshaft during the radial play measurement

6 -

Conrod

q	With industrially cracked conrod cap.

q	Renew as set only.

q	Mark cylinder number -B-

q	Fitting position: The marks -A- should point towards the pulley

q	With a drilled hole for lubricating the piston pin

7 -

Circlip

8 -	Piston pin

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

q	Removing and installing with the awl -T20019-

9 -

Piston

q	check → Fig.

q	Mark installation position and cylinder number.

q	Arrow on piston crown points to belt pulley end.

q	Install using piston ring clamp.

q	Piston and cylinder dimensions → Chapter

q	Checking cylinder bores → Fig..

10 -	Piston rings

q	Displace the gaps at 120° from each other

q	Use piston ring pliers to remove and install.

q	„TOP“ faces towards piston crown.

q	Piston ring ends: check clearance → Fig.

q	Checking ring-to-groove clearance → Fig..

Checking piston ring gap Special tools and workshop equipment required t  Calibre –  Insert ring at right angles from above into lower cylinder opening approx. 15 mm from edge of cylinder. Push in using a piston without piston rings.

Piston ring dimensions in mm	new	Wear limit
Compression ring	0.20 ... 0.40	0.8
Oil scraping ring	0.25 ... 0.50	0.8

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

Piston ring dimensions in mm	new	Wear limit
Compression ring	0.06 ... 0.09	0.20
Oil scraping ring	0.03 ... 0.06	0.15

Checking pistons Special tools and workshop equipment required t  Outer micrometer 75... 100 mm Measure pistons approx. 10 mm from lower edge of skirt, vertical to the piston pin axis. Deviations compared to the nominal value: max. 0.04 mm

Checking cylinder bores Special tools and workshop equipment required t  Interior bore 50 ... 100 mm –  Measure at 3 different points, crossways, across the engine -A- and in line with crankshaft -B-. Deviations compared to the nominal value: max. 0.08 mm   Note Measuring the cylinder bores must not be done when the cylinder block is fixed to thesupport tool -T20172-, as incorrect measurements may result.

Half-bearing: installation position Upper bearing shell -1- with a drilled hole for lubricating -arrow- the piston pin Lower bearing shell -2- without a drilled hole for lubricating the piston pin –  Fit the bearing shells centrally in the conrod or in the conrod bearing cap. Distance -a- should be identical on both sides.