SEAT Workshop Service and Repair Manuals

Piston and connecting rod: disassembly and assembly

1 -	Safety key

2 -	Piston pin

q	If difficult to move, heat the piston to 60 oC

q	Remove and fit with the -T20019-

3 -

Piston

q	Testing → Fig.

q	Mark the fitting position and correspondence to the respective cylinder

q	The arrow on the piston head should point towards the pulley

q	Fit with sleeve for fitting rings

4 -	Compression rings

q	Stagger the cuts in 120o

q	Remove and fit the rings with ring pliers

q	The “TOP” mark must face the piston head

q	Check the play between the ends of the rings → Fig.

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

5 -	Oil scraper rings

q	Carefully remove and fit by hand the two parts of the rings

q	The “TOP” mark must face the piston head

q	Check the play between the ends of the rings → Fig.

q	Check the coupling play between the rings and the piston groove → Fig.

6 -	Connecting rod

q	Always replace the unit

q	Mark the correspondence to the cylinder -A-

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

q	Axial guide per piston

7 -	Connecting rod caps

q	Check the fitting position

q	Cracked connecting rods can be fitted in only one position and only with the corresponding connecting rod

8 -	Connecting rod bolt, 20 Nm + 1/4 turn (90o)

q

Replace

q	Lubricate the thread and support surface

q	Too measure the radial play tighten to 20 Nm, without retightening

q	Retightening may be done in several steps

q	The retightening angle may be measured with protractor -T20030-

9 -	Aluminium engine block

q	Check the bore of the cylinders → Fig.

q	Piston and cylinder dimensions → Chapter

10 -	Half bearing

q	Do not swap used half bearings

q	Fit the half bearings centred

q	Measure the radial play with Plastigage: New: 0.020...0.061 mm Wear limit: 0.091 mm When measuring the radial play do not turn the crankshaft

Checking ring gap –  From above fit the ring so that it is at a right angle in the lower opening in the cylinder, at about 15 mm from the edge of the cylinder.

Piston ring		Wear limit
Compression		1.0 mm
oil scraper		1.0 mm

Checking ring to groove clearance First clean the ring housing grooves:

Piston ring		Wear limit
Compression		1.5 mm
oil scraper		1.5 mm

Checking pistons Special tools and workshop equipment required t  Exterior micrometer 75...100 mm –  Measure approx. 10 mm from the lower edge, staggered 90o with respect to the axis of the piston pin. Divergence with respect to the nominal dimension max. 0.04 mm Nominal dimension → Chapter; Piston and cylinder dimensions.

Checking cylinder bore diameters Special tools and workshop equipment required t  Interior calliper 50...100 mm –  Measure at three points, crosswise, transversally -A- and lengthwise -B-. Divergence with respect to the nominal dimension 0.08 mm max. Nominal dimension → Chapter; Piston and cylinder dimensions.   Note! Do not measure cylinder bores with the engine fixed to assembly trestle -AR-2204 A- with engine support -T20082-, as the measurements may be erroneous.