Skoda Workshop Service and Repair Manuals

Piston and conrod - Summary of components

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	mark installation position and matching cylinder

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

q	arrow on the 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 dimension: Ø 80,95 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 60°C

q	use drift -VW 222A- for removing and installing

4 -

Circlip

q

replace

5 -

Conrod

q	with a split bearing cap

q	always replace as a set only

q	mark matching cylinder -A-

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

q	separate new conrod → Chapter

q	Axial clearance: Wear limit 0.37 mm

6 -	Bearing shell

q	Fitting position → Fig.

q	do not mix up already 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 → Fig.

q	pay attention to correct position

7 -	Cylinder block

q	Inspect cylinder → Fig.

q	Cylinder dimension: Ø 81,01 mm

8 -	Conrod bearing cap

q	Check fitting position

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

q	separate new conrod → Chapter

9 -	Oil injection nozzle

q	for piston cooling

q	removing and installing → Fig.

10 -	Pressure valve, 27 Nm

q	replace without sealant

q	removing and installing → Fig.

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

q

replace

q	Oil thread and 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 parts	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

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 parts	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 l  The arrow on the piston crown -arrows- faces towards the belt pulley side.

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 centre of the conrod bearing cap. l  Dimension -a- = 2.5 mm

Oil spray nozzle and pressure valve 1 -  Screw with pressure valve 2 -  Oil spray nozzle (for cooling piston) l  Fitting position: Align the guide edge of the oil spray nozzle to the edge of the cylinder block being worked on.   Note t  The oil injection nozzles must not be bent. t  Replace the oil injection nozzles if they are bent.