Skoda Workshop Service and Repair Manuals

Disassembling and assembling pistons and conrods (Octavia II)

1 -	Piston rings

q	Offset joint 120°

q	use piston ring pliers for removing and installing

q	marking “TOP” faces piston crown

q	Inspect gap clearance → Fig.

q	Inspect end clearance → Fig.

2 -

Piston

q	with combustion chamber

q	with oil labyrinth for cooling

q	mark installation position and matching cylinder

q	Installation position and assignment of piston/cylinder → Fig.

q	arrow on piston crown faces towards the belt pulley side

q	replace piston if there is any sign of crack formation on the piston body

q	Inspecting piston → Fig.

q	Piston: Ø 79.47 mm

q	use piston ring tensioning strap for installing

q	inspect piston projection at TDC → Chapter

3 -	Piston pin

q	if stiff, heat piston to approx. 60°C

q	with drift -VW 222A- removing and installing

4 -

Circlip

5 -

Conrod

q	always replace as a set only

q	mark matching cylinder -A-

q	Fitting position: Markings -B- point towards the belt pulley side

q	with a split bearing cap

q	separate new conrod → Chapter

6 -	Bearing shell

q	Fitting position → Fig.

q	do not mix up used bearing shells (mark)

q	Observe version: top bearing shell (towards the piston) must be made from a long lasting material, recognition feature for new bearing shells: black marking on the contact surface near the separation point

q	insert in middle

q	check for firm seating

q	Axial play wear limit: 0.37 mm

7 -	Cylinder block

q	inspect cylinder bore → Fig.

q	Cylinder: Ø 79.51 mm

8 -	Conrod bearing cap

q	Check fitting position

q	cracked cover fits only in one position at the relevant conrod

9 -	Oil injection nozzle

q	for cooling pistons

10 -

25 Nm

q	replace without sealant

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

q

replace

q	oil thread and head contact surface

Inspecting piston ring gap clearance Special tools and workshop equipment required t  Feeler gauges –  Insert ring at right angles from above down into lower cylinder opening, about 15 mm away from edge of cylinder. To insert use piston without rings.

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

Inspect piston ring end clearance Special tools and workshop equipment required t  Feeler gauges –  Clean before inspecting the annular grooves of the piston.

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

Inspecting pistons Special tools and workshop equipment required t  External micrometer –  Measure about 10 mm from the lower edge, offset at right angles to the piston pin shaft. l  Max. deviation from specified dimension: 0.04 mm.

Installation position and assignment of piston/cylinder Pistons in cylinders 1 and 2: l  Large piston relief for inlet valve to flywheel side -arrows-. Pistons in cylinders 3 and 4: l  Large piston relief for inlet valve to belt pulley side -arrows-.   Note t  For new pistons the cylinder assignment is colour-coded on the piston crown. t  Piston of cylinder 1 and 2: Marking 1/2. t  Piston of cylinder 3 and 4: Marking 3/4.

Inspecting cylinder bore Special tools and workshop equipment required t  Internal precision measuring instrument –  Measure cylinder at 3 points crosswise in transverse direction -A- and lengthwise -B-. l  Max. deviation from specified dimension: 0.10 mm.

Fitting position of the bearing shells in the conrods –  Insert bearing shell in the conrod or in the center of the conrod bearing cap. l  Dimension -a- = 2.5 mm