Audi Workshop Service and Repair Manuals

Pistons and conrods - exploded view

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.

Oil spray jet for piston cooling 1 -  Bolt, 9 Nm 2 -  Oil spray jet with spray nozzle valve for piston cooling

Checking piston ring gap –  Insert piston ring at right angle to cylinder wall from above and push down into lower cylinder opening approx. 15 mm from bottom of cylinder. –  Use a piston without piston rings to push in the ring.

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

Checking ring-to-groove clearance –  Clean groove in piston before checking clearance.

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

Checking piston –  Using a micrometer (75 ... 100 mm), measure approx. 10 mm from the lower edge, perpendicular to the piston pin axis. l  Maximum deviation from nominal dimension: 0.05 mm. Nominal dimension → Chapter „Piston and cylinder dimensions“.

Checking cylinder bore –  Use 50 ... 100 mm internal dial gauge to take measurements at 3 points in transverse direction -A- and longitudinal direction -B-. l  Maximum deviation from nominal dimension: 0.08 mm. Nominal dimension → Chapter „Piston and cylinder dimensions“.

Installation position of pistons l  Installation position: Arrow -item 1- on piston crown points to pulley end.   Note t  If used pistons are being re-installed, use chalk or waterproof felt-tip pen to mark installation position and cylinder number on piston crown. t  Do not use a centre punch or scriber, as this would damage the coating of the piston crown.

Marking conrods –  Before removing, mark mating positions of conrods and conrod bearing caps with coloured pen -arrow-.   Note t  Only renew conrods as a complete set. t  Do not interchange conrod bearings.

Conrod installation position The larger contact shoulder on the conrod -arrows- faces towards the adjacent main bearing.   Note Illustration shows front pair of conrods.