A3 Mk1
Pistons and conrods - exploded view |
Note
Oil spray jet and pressure relief valve → Fig. |
1 - | 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. |
2 - | Piston |
q | Checking → Fig. |
q | Mark installation position and cylinder number |
q | Arrow on piston crown points to pulley end |
q | Install using piston ring clamp |
q | Piston and cylinder dimensions → Chapter |
3 - | Conrod |
q | Only renew as a complete set |
q | Mark cylinder number -B- |
q | Installation position: Markings -A- face towards pulley end |
q | With oil drilling for piston pin lubrication |
4 - | Conrod bearing cap |
q | Mark cylinder number -B- |
q | Installation position: Markings -A- face towards pulley end |
5 - | 30 Nm + 90° (1/4 turn) further |
q | Renew conrod bolt → Item |
q | Lubricate threads and contact surface |
q | To measure radial clearance, tighten to 30 Nm but do not turn further |
6 - | Bearing shell |
q | Upper bearing shell with oil hole for piston pin lubrication |
q | Note installation position |
q | Do not interchange used bearing shells (mark positions) |
q | Ensure tight fit in retaining lugs |
q | Axial clearance (new): 0.10 ... 0.35 mm |
q | Axial clearance: wear limit: 0.40 mm |
q | Measuring radial clearance → Chapter |
7 - | Cylinder block |
q | Checking cylinder bore → Fig. |
q | Piston and cylinder dimensions → Chapter |
8 - | Conrod bolt |
q | Renew |
9 - | Circlip |
10 - | Piston pin |
q | If difficult to move, heat piston to approx. 60 °C |
q | Remove and install using drift -VW 222 A- |
Piston ring Dimensions in mm | New | Wear limit |
1st compression ring | 0.20 … 0.40 | 0.80 |
2nd compression ring | 0.20 … 0.40 | 0.80 |
Oil scraper ring | 0.25 … 0.50 | 0.80 |
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Piston ring Dimensions in mm | New | Wear limit |
1st compression ring | 0.06 … 0.09 | 0.20 |
2nd compression ring | 0.05 … 0.08 | 0.20 |
Oil scraper ring | 0.03 … 0.06 | 0.15 |
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