Volkswagen Workshop Service and Repair Manuals

Assembly overview - pistons and conrods

1 -	Conrod bolt

q	M8: 30 Nm + turn 90° further.

q	M9: 45 Nm + turn 90° further.

q

Renew.

q	Oil threads and contact surface.

q	Use old bolt for measuring radial clearance.

q	For radial clearance measurement, do not turn 90° further

2 -	Conrod bearing cap

q	Note installation position.

q	The caps only fit in one position and only on the appropriate conrod due to the breaking procedure (cracking) separating the cap from the conrod.

q	Mark with cylinder number -A-.

q	Installation position: Marking -B- faces towards pulley end.

3 -	Bearing shells

q	Installation position → Fig..

q	Do not interchange used bearing shells (mark).

q	Axial clearance new: 0.10…0.35 mm , wear limit: 0.40 mm

q	Measure radial clearance using Plastigage; new: 0.02…0.06 mm; wear limit: 0.09 mm. Do not rotate crankshaft when checking radial clearance.

4 -	Pressure relief valve

q

27 Nm

q	Opening pressure: 1.6…1.9 bar

5 -	Oil spray jet

q	For piston cooling.

6 -

Circlip

7 -	Piston pin

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

q	Remove and install using drift -VW 222 A-.

8 -

Piston

q	Check → Anchor.

q	Mark installation position and cylinder number.

q	Arrow on piston crown points to belt pulley end.

q	Install using piston ring clamp.

q	Piston and cylinder dimensions → Chapter.

q	Checking cylinder bores → Anchor.

9 -	Compression rings

q	Offset gaps by 120°.

q	Use piston ring pliers to remove and install.

q	„TOP“ must face towards piston crown

q	Checking ring gap → Fig..

q	Checking ring-to-groove clearance → Fig..

10 -	Oil scraper ring

q

2 parts

q	Offset gap of top steel element of piston ring by 120° to next compression ring

q	Offset gaps of individual parts of oil scraper ring.

q	Checking ring gap → Fig..

q	Ring-to-groove clearance cannot be checked.

11 -

Conrod

q	Renew as set only.

q	Mark with cylinder number -A-.

q	Installation position: Marking -B- faces towards pulley end.

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

Piston ring dimensions in mm	New	Wear limit
compression ring	0.20 … 0.40	0.8
Oil scraper ring	0.25 … 0.50	0.8

Checking ring-to-groove clearance –  Clean ring groove of piston before checking.

Piston ring dimensions in mm	New	Wear limit
1st compression ring	0.06 … 0.09	0.20
2nd compression ring	0.03 … 0.06	0.15
Oil scraper rings	Not measurable

Checking piston Special tools and workshop equipment required t  Micrometer 75 - 100 mm -VAS 6071-

–  Measure approx. 10 mm from the bottom edge, perpendicular to the piston pin axis. t  Deviation from nominal dimension max. 0.04 mm Checking cylinder bores Special tools and workshop equipment required t  Cylinder gauge -VAS 6078-   Caution The cylinder bore may not be worked on (reboring, honing, grinding) may not be carried out using workshop tools! This will damage the surface of the cylinder bore.

–  Take measurements at 3 positions in both lateral direction -A- and longitudinal direction -B-. t  Deviation from nominal dimension max. 0.08 mm   Note Cylinder bores must not be measured when cylinder block is mounted on engine and gearbox support -VAS 6095-, as measurements may be incorrect.

Installation position of bearing shell –  Position bearing shells in centre of conrod and conrod bearing cap when fitting. Dimension -a- must be identical on both sides.