A4 Cabriolet Mk2
Pistons and conrods - exploded view |
Note
Oil spray jet for piston cooling → Fig.. |
1 - | Conrod bolts, 30 Nm + turn 90° 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 in colour -B- → Fig. |
q | Installation position: Note position of lugs on casting -A- |
3 - | Bearing shells |
q | Note installation position |
q | Renew used bearing shells |
q | Measuring radial clearance → Chapter |
q | For measuring radial clearance, tighten bolts -item 1- to 30 Nm but do not turn further |
4 - | Conrod |
q | Only renew as a complete set |
q | Mark cylinder allocation in colour -B- → Fig. |
q | Installation position: Note position of lugs on casting -A- |
q | Axial clearance for each conrod pair (when new): 0.20 … 0.44 mm |
5 - | Circlip |
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 | Mark installation position and cylinder number → Fig. |
q | Checking → Fig. |
q | Install using piston ring clamp |
q | If cracking is visible on piston skirt, renew piston |
q | Piston and cylinder dimensions → Chapter |
q | Checking piston projection at TDC → Chapter |
q | Checking cylinder bore → Fig. |
8 - | Piston 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. |
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Piston ring Dimensions in mm | New | Wear limit |
1st compression ring | 0.25 … 0.38 | 0.80 |
2nd compression ring | 0.70 … 0.90 | 1.30 |
Oil scraper ring | 0.40 (maximum) | 0.70 |
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Piston ring Dimensions in mm | New | Wear limit |
1st compression ring | 0.120 … 0.160 | 0.175 |
2nd compression ring | 0.020 … 0.090 | 0.115 |
Oil scraper ring | 0.020… 0.090 | 0.115 |
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