A4 Cabriolet Mk2
Pistons and conrods - exploded view of components |
Note
Oil spray jet for piston cooling → Fig.. |
1 - | Conrod bolt, 30 Nm + 90° (1/4 turn) further |
q | Renew |
q | Lubricate threads and contact surface |
q | To measure radial clearance, tighten to 30 Nm but do not turn further |
2 - | Conrod bearing cap |
q | Do not interchange |
q | Mark cylinder allocation with a coloured pen -B- → Fig. |
q | Note when fitting bearing cap: the wide contact shoulder -A- must point towards same side on conrod and conrod bearing cap |
q | Installation position of conrod pairs → Fig. |
3 - | Bearing shells |
q | Ensure that retaining lugs are securely seated. |
q | Do not interchange used bearing shells (mark accordingly, but not on the running surface) |
q | Measuring radial clearance → Chapter |
q | To measure radial clearance, tighten bolts → Item to 30 Nm but do not turn further |
q | There are oversized bearings available for machined crankshaft conrod journals → Parts catalogue |
4 - | Conrod |
q | Only renew as a complete set |
q | Mark cylinder allocation in colour -B- → Fig. |
q | Note when fitting bearing cap: the wide contact shoulder -A- must point towards same side on conrod and conrod bearing cap |
q | Installation position of conrod pairs → Fig. |
q | Axial clearance for each conrod pair (when new): 0.20 … 0.38 mm |
q | Wear limit (axial clearance): 0.60 mm |
q | Measuring radial clearance → Chapter |
5 - | Piston pin |
q | If difficult to move, heat piston to approx. 60 °C |
q | Remove and install using drift -VW 222 A- |
6 - | Circlip |
7 - | Piston |
q | Installation position for piston → Fig. |
q | Piston and cylinder dimensions → Chapter |
q | Checking → Fig. |
q | Install using piston ring clamp |
q | Measuring cylinder bore → Fig. |
8 - | Piston rings |
q | Offset gaps by 120° |
q | Use piston ring pliers to remove and install |
q | Marking “TOP” or side with identification mark must face piston crown |
q | Measuring ring gap → Fig. |
q | Measuring ring-to-groove clearance → Fig. |
Piston ring (in mm) | New | Wear limit |
1st compression ring | 0.25 … 0.40 | 0.8 |
2nd compression ring | 0.20 … 0.40 | 0.8 |
Oil scraper ring | – | 0.4 |
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Piston ring (in mm) | New | Wear limit |
1st compression ring | 0.04 … 0.08 | 0.20 |
2nd compression ring | 0.005 … 0.045 | 0.20 |
Oil scraper ring | 0.01 … 0.05 | 0.15 |
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