A5
Pistons and conrods - exploded view |
1 - | Bolt |
q | Renew |
q | Lubricate threads and contact surface |
q | 30 Nm + turn 90° further |
2 - | Conrod bearing cap |
q | Due to the cracking method used to separate the bearing cap from the conrod in manufacture, the caps only fit in one position and only on the appropriate conrod |
q | Mark cylinder allocation in colour -B- |
q | Installation position: Markings -A- face towards pulley end |
3 - | Bearing shell |
q | Installation position → Fig. |
q | Renew used bearing shells |
q | Note version: Upper bearing shell (closest to piston) is constructed from a more wear-resistant material. Distinguishing feature on new bearing shells: black marking on bearing surface near joint |
q | Check that it is securely seated |
4 - | Conrod |
q | Only renew as a complete set |
q | With industrially cracked conrod bearing cap |
q | Separating parts of new conrod → Fig. |
q | Mark cylinder allocation in colour -B- |
q | Installation position: Markings -A- face towards pulley end |
q | Axial clearance: wear limit: 0.37 mm |
q | Measuring radial clearance → Chapter |
5 - | Circlip |
q | Renew |
6 - | Piston pin |
q | If difficult to move, heat piston to approx. 60 °C |
q | Remove and install using drift -VW 222 A- |
7 - | Piston |
q | With combustion chamber |
q | Version fitted in vehicle may differ from illustration |
q | Mark installation position and cylinder number → Fig. |
q | Checking → Fig. |
q | Install using piston ring clamp |
q | Piston and cylinder dimensions → Chapter |
q | Measuring cylinder bore → Fig. |
q | Measuring piston projection at „TDC“ → Chapter |
8 - | Piston rings |
q | Compression 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. |
9 - | Piston ring |
q | Oil scraper ring |
q | Offset gap 120° from bottom compression ring |
q | Use piston ring pliers to remove and install |
q | Measuring ring gap → Fig. |
q | Measuring ring-to-groove clearance → Fig. |
Piston ring | new mm | Wear limit mm |
1st compression ring | 0.25 … 0.40 | 1.00 |
2nd compression ring | 0.25 … 0.40 | 1.00 |
Oil scraper ring | 0.25 … 0.50 | 1.00 |
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Piston ring | new mm | Wear limit mm |
1st compression ring | 0.06 … 0.09 | 0.25 |
2nd compression ring | 0.05 … 0.08 | 0.25 |
Oil scraper ring | 0.03 … 0.06 | 0.15 |
Note
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