A5
Pistons and conrods - exploded view |
1 - | Bolts |
q | Renew |
q | Lubricate threads and contact surface |
q | 30 Nm + turn 90° further |
2 - | Conrod bearing cap |
q | Mark installation position for re-installation |
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. |
3 - | Bearing shell |
q | Ensure that retaining lugs are securely seated. |
q | Mark used bearing shells for re-installation but not on bearing surface |
q | Bearing shells worn down to base layer must be renewed |
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 | Measuring radial clearance → Chapter |
5 - | Piston pin |
q | If difficult to remove, heat piston to approx. 60 °C |
q | Remove and install using drift -VW 222 A- |
6 - | Circlip |
q | Renew |
7 - | Piston |
q | Mark installation position and cylinder number → Fig. |
q | Arrow on piston crown points to pulley end |
q | Checking → Fig. |
q | Renew piston if cracking is visible on piston crown or piston skirt |
q | Install using piston ring clamp |
q | Piston and cylinder dimensions → Chapter |
q | Measuring cylinder bore → Fig. |
8 - | Piston rings |
q | Offset gaps by 120° |
q | Use piston ring pliers to remove and install |
q | Installation position: marking “TOP” or side with lettering faces towards piston crown |
q | Measuring ring gap → Fig. |
q | Measuring ring-to-groove clearance → Fig. |
Piston ring | new mm | Wear limit mm |
1st compression ring | 0.35 … 0.50 | 0.8 |
2nd compression ring | 0.60 … 0.80 | 1.0 |
Oil scraper ring | 0.25 … 0.50 | 0.8 |
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Piston ring | new mm | Wear limit mm |
Compression rings | 0.02 … 0.08 | 0.20 |
Oil scraper ring | 0.02 … 0.08 | 0.15 |
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