SEAT Workshop Service and Repair Manuals

Piston and piston rod: removing and fitting

1 -	Piston rings

q	Displace gaps 120º

q	Remove and install with piston ring pliers

q	The labelling “TOP” must face towards piston crown

q	Checking end clearance → Fig.

q	Check clearance between the piston rings and the grooves → Fig.

2 -

Piston

q	Testing → Fig.

q	Mark installation position and respective cylinder

q	Arrow on piston crown points to crankshaft pulley end

q	Install using piston ring installation sleeve

q	Piston and cylinder measurements → Chapter

3 -	Piston spring pin

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

q	Removing and installing with the tappet -T20019-

4 -	Safety washer

q

Replace

5 -

Conrod

q	Renew the set only.

q	Mark cylinder correspondence -B-

q	Marks -A- must face towards pulley

q	With a drilled hole for lubricating the piston pin

6 -	Bearing shell

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

q	Note installation position → Fig.

q	Do not interchange used bearing shells

q	Check for secure seating.

q	Axial play:

q	New: 0.10 … 0.35 mm

q	Wear limit: 0.4 mm

q	Measure the radial play with Plastigage

q	New: 0.01 … 0.05 mm

q	Wear limit: 0.12 mm

q	When measuring the radial play, do not rotate the crankshaft

7 -	Engine block

q	Check cylinder bore → Fig.

q	Piston and cylinder measurements → Chapter

8 -	Conrod bearing caps

q	Note installation position

q	Conrods divided by fracturing “cracking” can only be fitted in one position and only with the corresponding conrod

9 -	30 Nm +1/4 turn (90º)

q

Replace

q	Oil threads and contact surface.

q	To measure radial clearance tighten to 30 Nm

Piston ring ends: check gap Special tools and workshop equipment required t  Gauge Checking procedure –  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
1º compression ring		0,20…0,40	0,8
Oil scraper ring	mm	0,25…0,50	0,8

Checking play between the rings and grooves Special tools and workshop equipment required t  Gauge Checking procedure –  First clean piston ring housing groove.

Piston ring		Clearance
		New	Wear limit
1º compression ring	mm	0,06…0,09	0,20
Oil scraper ring	mm	0,03…0,06	0,15

Check the pistons Special tools and workshop equipment required t  Exterior micrometer 75 … 100 mm. Checking procedure –  Measure to approx. 10 mm from the lower edge, perpendicular to the pin axis. Tolerance regarding nominal measurement: max. 0.04 mm.

Bearing shells, fitting position Bearing shell -1- with oil hole -arrow- for conrod. Bearing shell -2- with no hole for conrod cover. –  Fit the bearing shells to the conrod and fit the conrod cover in the centre. Measurement -a- must be the same on left and right, max. tolerance: 0.2 mm.

Check the cylinder bores Special tools and workshop equipment required t  Bore gauge 50 … 100 mm. Checking procedure –  Take measurements at 3 diagonal positions, sideways -A- and lengthways -B-. –  Maximum tolerances in relation to the max. nominal measurement 0.08 mm.   Note Measuring the cylinder bores must not be done when the cylinder block is fixed to thecounterhold -T20172/1, /2, /3,-, as incorrect measurements would then be possible.