Skoda Workshop Service and Repair Manuals

Disassembling and assembling pistons and conrods

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

q

replace

q	Oil thread and contact surface

2 -	Conrod bearing cap

q	do not interchange

q	mark assignment to cylinder -B- → Fig.

q	Fitting location: take note of the markings on the casting -A- → Fig.

3 -	Bearing shell

q	Check fitting position

q	do not mix up used bearing shells (mark)

q	new axial play for each new conrod pair: 0.20...0.44 mm, wear limit: 0.60 mm

4 -

Conrod

q	with a split bearing cap

q	always replace as a set only

q	mark assignment to cylinder -B-

q	Fitting location: take note of the markings on the casting -A- → Fig.

5 -

Circlip

6 -	Piston pin

q	if stiff, heat piston to 60°

q	with drift VW 222A removing and installing

7 -

Piston

q	Ø Piston: 78.253...78.261

q	Ø Cylinder: 78.306...78.310

q	with combustion chamber

q	mark installation position and matching cylinder

q	check → Fig.

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

q	arrow on piston crown faces towards the middle of the engine

q	use piston ring tensioning strap for installing

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

q	inspect piston projection at TDC → Chapter

8 -	Piston rings

q	Offset joint 120 °

q	use piston ring pliers for removing and installing

q	marking “TOP” must face towards piston crown

q	Inspect gap clearance → Fig.

q	Inspect end clearance → Fig.

9 -

9 Nm

10 -	Oil injection nozzle

q	for cooling pistons

Inspect piston ring gap clearance –  Push in ring at right angles to the cylinder wall from the top through to the bottom cylinder opening, about 15 mm from the cylinder edge. To insert use piston without rings.

Piston ring dimension in mm	New	Wear limit
1. Compression ring	0,20 ... 0,40	0,8
2. Compression ring	0,80 ... 1,00	1,4
Oil scraper ring	0,25 ... 0,50	0,8

Inspect piston ring end clearance –  Clean before inspecting the annular groove of the piston.

Piston ring dimension in mm	New	Wear limit
1. Compression ring	0,100...0,135	0,150
2. Compression ring	0,045...0,085	0,110
Oil scraper ring	0,025...0,065	0,090

Inspecting pistons –  Measure about 10 mm from the lower edge, offset at right angles to the piston pin shaft. t  Variations compared to nominal dimension max. 0.05 mm

Inspecting cylinder bore Special tools and workshop equipment required t  Internal precision measuring instrument 50...100 mm –  Measure at 3 points crosswise in a transverse direction -A- and lengthwise -B-. t  Variations compared to nominal dimension max. 0,08 mm

Installation position and assignment of piston/cylinder The pistons for cylinders 1...3 and 4...6 are different to each other. t  Fitting location: The arrows on the piston crowns must point towards the middle of the engine. –  Mark the order on the piston crown using an indelible felt-tip pen.   Note Do not use a centre punch since one may incur subsequent damage (cracks). For new pistons the cylinder assignment is colour-coded on the piston crown or engraved. t  Piston for cylinder 1, 2 and 3: Marking 1/2/3 t  Piston for cylinder 4, 5 and 6: Marking 4/5/6

Marking conrods   Note t  Always replace conrods only as a set. t  Do not interchange the conrod bearings. –  Mark the conrods and conrod bearing journals as a pair before removing -arrow-.

Conrod installed position The casting markings -arrows- → Item for the conrods lie as shown in the illustration.   Note The illustration shows them on the front conrod pair.