Audi Workshop Service and Repair Manuals

Pistons and conrods - exploded view

1 -

Bolts

q

Renew

q	Lubricate threads and contact surface

q	30 Nm + turn 90° further

2 -	Conrod bearing cap

q	Mark installation position for re-installation

q	Mark cylinder allocation in colour -B- → Fig.

q	Note when fitting bearing cap: the wide contact shoulder -A- must point towards same side on conrod and conrod bearing cap

q	Installation position of conrod pairs → Fig.

3 -	Bearing shell

q	Ensure that retaining lugs are securely seated.

q	Mark used bearing shells for re-installation but not on bearing surface

q	Bearing shells worn down to base layer must be renewed

4 -

Conrod

q	Only renew as a complete set

q	Mark cylinder allocation in colour -B- → Fig.

q	Note when fitting bearing cap: the wide contact shoulder -A- must point towards same side on conrod and conrod bearing cap

q	Installation position of conrod pairs → Fig.

q	Measuring radial clearance → Chapter

5 -	Piston pin

q	If difficult to remove, heat piston to approx. 60 °C

q	Remove and install using drift -VW 222 A-

6 -

Circlip

q

Renew

7 -

Piston

q	Mark installation position and cylinder number → Fig.

q	Arrow on piston crown points to pulley end

q	Checking → Fig.

q	Renew piston if cracking is visible on piston crown or piston skirt

q	Install using piston ring clamp

q	Piston and cylinder dimensions → Chapter

q	Measuring cylinder bore → Fig.

8 -	Piston 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.

Measuring piston ring gap –  Insert ring at right angle to cylinder wall from above and push down into lower cylinder opening approx. 15 mm from bottom of cylinder. –  To do so, use a piston without rings.

Piston ring	new mm	Wear limit mm
1st compression ring	0.35 … 0.50	0.8
2nd compression ring	0.60 … 0.80	1.0
Oil scraper ring	0.25 … 0.50	0.8

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

Piston ring	new mm	Wear limit mm
Compression rings	0.02 … 0.08	0.20
Oil scraper ring	0.02 … 0.08	0.15

Checking piston –  Using a micrometer (75 ... 100 mm), measure approx. 15 mm from the lower edge, perpendicular to the piston pin axis. l  Maximum deviation from nominal dimension: 0.04 mm. Nominal dimension → Chapter „Piston and cylinder dimensions“.

Measuring cylinder bore –  Use a cylinder gauge -VAS 6078- to take measurements at 3 points in transverse direction -A- and in longitudinal direction -B-. l  Maximum deviation from nominal dimension: 0.08 mm. Nominal dimension → Chapter „Piston and cylinder dimensions“.

Installation position of pistons   Caution Do not damage the coating of the piston crown. Use a coloured pen to mark piston/cylinder allocation on piston crown for re-installation. Do not mark piston crown by means of centre punch, notch or the like. Installation position: l  Arrows on piston crowns point to pulley end.

Marking conrods   Note Only renew conrods as a complete set. –  Use a coloured pen to mark matching conrods and conrod bearing caps with cylinder numbers -arrow- for re-installation.

Installation position of conrods l  The cast lugs -arrows- on the ground surfaces of the conrod pairs “1 and 2”, “3 and 4”, and “5 and 6” must face each other.

Oil spray jet for piston cooling 1 -  Apply locking fluid to bolt and tighten to 9 Nm; for locking fluid refer to → Electronic parts catalogue. 2 -  Oil spray jet with spray nozzle valve (opening pressure: 2 ... 2.4 bar)   Note t  Take care not to bend oil spray jets. t  Always renew bent oil spray jets.