SEAT Workshop Service and Repair Manuals

Pistons and conrods - general over view of components Piston ring ends: check clearance → Fig. Check play with piston groove → Fig. Checking piston → Fig.. Installation position and piston/cylinder correspondence → Fig. Checking cylinder bores → Fig.. Oil jets and pressure release valve → Fig. Separating new conrod → Fig.. Installation position of the bearing shells → Fig..

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

q

Renew

q	Oil threads and contact surface.

q	To measure the radial play, use used bolts

2 -	Conrod bearing cap

q	Mark cylinder number -B-

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

3 -	Bearing shell

q	Installation position → Fig..

q	Do not interchange used bearing shells (mark).

q	Note design: Upper half-bearing (to piston) made from more resistant material. Distinguishing factors with new bearing shells: Black line on the contact surface in the cutting area

q	Check for secure seating.

q	Axial clearance: Wear limit: 0.37 mm

q	Check radial clearance with Plastigage.

q	Do not rotate crankshaft when checking radial clearance.

q	Radial play; wear limit: 0.08 mm

4 -

Conrod

q	Renew as set only.

q	Mark cylinder number -B-

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

5 -

Circlip

6 -	Piston pin

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

q	Remove and install with the installation tool -VW 222 A-, see equivalent → Anchor

7 -

Piston

q	With combustion chamber

q	Mark the installation position and the cylinder correspondence

q	Installation position and allocation of piston to cylinder → Fig..

q	Arrow on piston crown points to belt pulley end.

q	If the piston is scratched, replace it

q	Checking piston → Fig..

q	Piston and cylinder dimensions → Chapter.

q	Checking cylinder bores → Fig..

q	Install using piston ring clamp.

q	Checking piston position at TDC → Chapter

8 -	Piston rings

q	Compression rings

q	Displace the gaps at 120° from each other

q	Use piston ring pliers to remove and install.

q	„TOP“ must face towards piston crown

q	Piston ring ends: check clearance → Fig.

q	Check play with piston groove → Fig.

9 -	Piston ring

q	Oil scraper ring

q	Displace the gaps by 120° towards the lower compression ring

q	Use piston ring pliers to remove and install.

q	Piston ring ends: check clearance → Fig.

q	Check play with piston groove → Fig.

Checking piston ring gap –  Push ring squarely from above down to approx. 15 mm from bottom end of cylinder. Push in using a piston without piston rings.

Piston ring (Dimensions in mm)	New	Wear limit
1. compression ring	0,20 … 0,40	1,00
2. compression ring	0,20 … 0,40	1,00
Oil scraper ring	0,25 … 0,50	1,00

Checking ring-to-groove clearance –  Before the test, clean the neck for the piston ring.

Piston ring (Dimensions in mm)	New	Wear limit
1. compression ring	0,06 … 0,09	0,25
2. compression ring	0,05 … 0,08	0,25
Oil scraper ring	0,03 … 0,06	0,15

Checking piston –  Measure pistons approx. 10 mm from the lower edge of skirt, at 90° to the piston pin axis. l  Maximum deviation from the nominal dimension: max. 0.04 mm

Installation position and piston/cylinder correspondence l  The arrow points to the cylinder 1 -arrows-.

Checking cylinder bores –  Measure, with a precision interior gauge 50 … 100 mm at three different points across in a transversal -A- and longitudinal direction -B-. l  Maximum deviation from the nominal dimension: max. 0.10 mm

Oil spray jet and pressure relief valve 1 -  Bolt with pressure relief valve, 27 Nm 2 -  Oil spray jet for cooling piston

Separating new conrod On new conrods it is possible that the breaking point is not fully separated. Proceed as follows, when the conrod bearing cap cannot be removed by hand: –  Mark the conrod correspondence to the cylinder –  Gently clamp conrod, as shown in illustration, in a vice with soft aluminium jaws.   Note t  Secure the conrod slowly so that it does not break. t  The conrod is attached below the cutting line. –  Unscrew the two bolts -arrows- approx. 5 turns.

–  Using a plastic hammer, carefully knock against conrod bearing cap in -direction of arrow- until it is loose.

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. Dimension -a- must be identical on both sides.