SEAT Workshop Service and Repair Manuals

Piston and connecting rod: disassembly and assembly

1 -	Piston rings

q	Stagger the cuts by 120°

q	Remove and install, with the help of pliers for rings

q	Carefully remove and install the oil scraper rings made up of three pieces, by hand

q	The word “TOP” indicates the piston head

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

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

2 -

Piston

q	Check → Fig.

q	Mark the assembly position and the cylinder to which it belongs.

q	The arrow on the piston head should point toward the pulley.

q	Assemble with casing to assemble rings.

3 -	Piston pin

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

q	Remove and install with -T20019-

4 -	Securing washer

5 -	Connecting rod

q	Renew unit only

q	Mark the position on cylinder -A-

q	Assembly position: the marks -B- should point toward the pulley

q	Axial guided by piston

6 -	Half bearings

q	Place the half bearings on the block, ensuring they are centred

q	Ensure that used half bearings are not used.

First measure pre-tension → Fig.

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.

7 -	Engine block

q	Check the bore of the cylinders → Fig.

q	Pistons and cylinder dimensions → Chapter

8 -	Connecting rod caps

q	Check the assembly position

q	If the connecting rods are cracked, the cap can only be placed in one position, and only on a given connecting rod

9 -	Connecting rod bolt

M7: 20 Nm + 1/4 turn (90°)

M8: 30 Nm + 1/4 turn (90°)

q

Renew

q	Apply lubricant to the threads and contact surface

q	To measure the radial play, tighten to 20 or 30 Nm, without retightening.

Check the play between the ends of the piston rings –  Install the ring from above, so that it is at a straight angle to the lower cylinder opening, and separated approximately 15 mm from the cylinder edge.

Piston ring		Wear limit
Ring compression		1.0 mm
Oil scraper rings	1 piece 3 pieces	1.0 mm _ → Note

1)	It is not possible to make an indication as to the wear limit.

Check the play between piston rings and piston grooves –  First clean the piston ring grooves.

Piston ring		Wear limit
Ring compression		0.15 mm
Oil scraper rings	1 piece 3 pieces	0.15 mm not measured

Check the pistons Special tools and workshop equipment required t  Exterior micrometer 75 … 100 mm –  Measure approximately 10 mm from the lower edge, staggering 90° from the piston pin shaft. Divergence over nominal dimensions max. 0.04 mm.

Check the bore of the cylinders Special tools and workshop equipment required t  Interior gauge 50 … 100 mm –  Measure at three points, crosswise -A- and lengthwise -B-. Variations over nominal dimension max. 0.08 mm.   Note! The cylinder bore should not be measured when the engine block is fixed to the assembly trestle by engine mount -AR-2204 A-, as erroneous measurements can result.

Measure the pre-tension of the half bearings Special tools and workshop equipment required t  Gauge The pre-tension of the half bearing is calculated as follows:

	dimension -a- of the half bearing
-	diameter of the connecting rod -b-
=	pre-tension

Minimum dimension: 1.5 mm If the pre-tension is not reached: –  Renew the half bearing.