Skoda Workshop Service and Repair Manuals

Disassembling and assembling pistons and conrods 1 -  Piston rings –  Offset joint 120° –  use piston ring pliers for removing and installing –  Marking “TOP” faces piston crown –  Inspect gap clearance → Fig. –  Inspect end clearance → Fig. 2 -  Piston –  with combustion chamber –  mark installation position and matching cylinder –  Installation position and assignment of piston/cylinder → Fig. –  arrow on piston crown faces towards the belt pulley –  use piston ring tensioning strap for installing –  replace piston if there is any sign of crack formation on the piston body –  inspect piston projection at TDC → Chapter –  Ø Piston = 79.47 mm 3 -  Piston pin –  if stiff, heat piston to 60°C –  removing and installing with -MP 3-400- 4 -  Circlip 5 -  Conrod –  always replace as a set only –  mark matching cylinder -A- –  Fitting position: Markings -B- point towards the belt pulley side 6 -  Bearing shell –  pay attention to correct installation position –  do not mix up used bearing shells –  ensure tightly located in retaining lugs –  Axial play wear limit: 0.37 mm 7 -  Cylinder block –  inspect cylinder bore → Fig. –  Ø Cylinder = 79.51 mm 8 -  Conrod bearing cap –  mark matching cylinder -A- –  Fitting position: Markings -B- point towards the belt pulley side 9 -  Oil injection nozzle –  for piston cooling 10 -  25 Nm –  with the overpressure valve –  replace without sealant 11 -  30 Nm + torque a further 1/4 turn (90°) –  replace –  Oil thread and contact surface

Inspecting piston ring gap clearance Special tools and workshop equipment required t  Feeler gauge Test sequence –  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.

Piston ring dimensions in mm	new	Wear limit
1. Compression ring	0,20...0,40	1,0
2. Compression ring	0,20...0,40	1,0
Oil scraper ring	0,25...0,50	1,0

Inspect piston ring end clearance Special tools and workshop equipment required t  Feeler gauge –  Clean before inspecting the annular groove 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 cylinder bore Special tools and workshop equipment required t  Internal fine measuring instrument 50...100 mm Test sequence –  Measure cylinder at 3 points crosswise in transverse direction -A- and lengthwise -B-. t  Variations compared to nominal dimension max. 0.10 mm   Note Do not measure the cylinder bore if the cylinder block is fixed to the assembly stand with the engine and gearbox mount -MP 1-202 -, as this may result in incorrect measurements.

Piston fitting position and assignment of the piston/cylinder Special tools and workshop equipment required t  Electric stylus Work procedure –  Mark the fitting position and assignment on the piston inner side (not on the piston crown) using an electric stylus or a marker. Pistons in cylinders 1 and 2: Large piston relief for inlet valve to flywheel side -arrows-. Pistons in cylinders 3 and 4: 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