Audi Workshop Service and Repair Manuals

Pistons and conrods - exploded view of components

Oil spray jet and pressure relief valve → Fig.

1 -	Conrod bolt, 30 Nm + 90° (1/4 turn) further

q

Renew

q	Lubricate threads and contact surface

q	Use old bolt for measuring radial clearance

q	To measure radial clearance, tighten to 30 Nm but do not turn further

2 -	Conrod bearing cap

q	Mark cylinder allocation -B-

q	Installation position: Markings -A- face towards pulley side

3 -	Bearing shells

q	Upper bearing shell with oil hole for piston pin lubrication

q	Installation position → Fig.

q	Do not interchange used bearing shells (mark positions)

q	Axial clearance when new: 0.09 ... 0.35 mm; wear limit: 0.40 mm

q	Measuring radial clearance → Chapter

q	To measure radial clearance, tighten bolts → Item to 30 Nm but not further

4 -

Conrod

q	Only renew as a complete set

q	Mark cylinder allocation -B-

q	Installation position: Markings -A- face towards pulley side

q	With oil passage for piston pin lubrication

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	Checking → Fig.

q	Mark installation position and cylinder allocation

q	Arrow on piston crown points to pulley end

q	Install using piston ring clamp

q	Piston and cylinder dimensions → Chapter

q	Checking cylinder bore → Fig.

8 -	Piston rings

q	Compression ring

q	Offset gaps by 120°

q	Remove and install using piston ring clamp

q	“TOP” must face towards piston crown

q	Checking ring gap → Fig.

q	Checking ring-to-groove clearance → Fig.

9 -	Piston ring

q	Oil scraper ring

q

3 pieces

q	Offset gap of top steel element of piston ring by 120° to next compression ring

q	Offset gaps of individual parts of oil scraper ring

q	Checking ring gap → Fig.

q	Checking ring-to-groove clearance → Fig.

Checking 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 Dimensions in mm	New	Wear limit
Compression rings	0.20 … 0.40	0.80
Steel elements of oil scraper ring	0.20 … 0.60	0.90

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

Piston ring Dimensions in mm	New	Wear limit
Compression rings	0.06 … 0.09	0.20
Oil scraper rings	0.04 … 0.12	0.20

Checking piston –  Measure approx. 10 mm from the bottom edge, perpendicular to the piston pin axis. l  Difference between measured value and nominal value: max. 0.04 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  Difference between measured value and nominal value: max. 0.08 mm. Nominal dimension → Chapter „Piston and cylinder dimensions“.

Installation position of bearing shells in conrods –  Insert bearing shells in centre of conrod/conrod bearing cap. l  Dimension -a- = 3.0 mm.   Note The bearing shell with the oil bore must be inserted in the conrod.

Oil spray jet and pressure relief valve 1 -  Bolt with pressure relief valve, 27 Nm 2 -  Oil spray jet for piston cooling