A4 Mk3
| Pistons and conrods - exploded view |
| 1 - | Piston rings |
| q | Offset gaps by 120° |
| q | Use piston ring pliers to remove and install |
| q | Inscription „TOP“ faces towards piston crown |
| q | Checking ring gap → Fig. |
| q | Checking ring-to-groove clearance → Fig. |
| 2 - | Piston |
| q | With combustion chamber |
| q | Mark installation position and cylinder number |
| q | Installation position and allocation of piston/cylinder → Fig. |
| q | Arrow on piston crown points to pulley end |
| q | Install using piston ring clamp |
| q | If cracking is visible on piston skirt, renew piston |
| q | Checking piston projection at TDC → Chapter |
| 3 - | Piston pin |
| q | If difficult to remove, heat piston to 60 °C |
| q | Remove and install using drift -VW 222 A- |
| 4 - | Circlip |
| 5 - | Conrod |
| q | Mark cylinder allocation -A- with coloured pen |
| q | Installation position: Marking -B- faces towards pulley end |
| q | With industrially cracked conrod bearing cap |
| 6 - | Bearing shell |
| q | Note installation position |
| q | Note version: Upper bearing shell (towards piston) made of a more wear resistant material. Identification: Black line on bearing surface in area of joint |
| q | Do not interchange used bearing shells |
| q | Insert bearing shells centrally |
| q | Check that it is securely seated |
| q | Axial clearance: wear limit: 0.37 mm |
| q | Check radial clearance with Plastigage: Wear limit: 0.08 mm. Do not rotate crankshaft when checking radial clearance |
| 7 - | Cylinder block |
| q | Checking cylinder bore → Fig. |
| q | Piston and cylinder dimensions → Chapter |
| 8 - | Conrod bearing cap |
| q | Note installation position |
| q | Due to the cracking method used to separate the bearing cap from the conrod in manufacture, the cap only fits in one position and only on the appropriate conrod |
| 9 - | Oil spray jet |
| q | For piston cooling |
| 10 - | Bolt for oil spray jet |
| q | 25 Nm |
| q | Insert without sealant |
| 11 - | Conrod bolt |
| q | 30 Nm + 90° |
| q | Renew |
| q | Lubricate threads and contact surface |
| q | Use old bolts when measuring radial clearance |
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| Piston ring Dimensions in mm | New | Wear limit |
| 1st compression ring | 0.20...0.40 | 1.0 |
| 2nd compression ring | 0.20...0.40 | 1.0 |
| Oil scraper ring | 0.25...0.50 | 1.0 |
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| Piston ring Dimensions in mm | New | Wear limit |
| 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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