Audi Workshop Service and Repair Manuals

Pistons and conrods - exploded view

1 -

Nut

q	Renew conrod bolt -item 13-

q	Lubricate threads and contact surface

q	30 Nm + 90°

2 -	Pressure relief valve

q	Opens at: 2.5 ... 3.2 bar

q

27 Nm

3 -	Oil spray jet

q	For piston cooling

4 -	Conrod bearing cap

q	Mark cylinder number -B-

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

5 -	Bearing shell

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

q	Bearing shells worn down to base layer must be renewed

q	Note installation position

q	Ensure tight fit in retaining lugs

6 -	Cylinder block

q	Checking cylinder bore → Fig.

q	Piston and cylinder dimensions → Chapter

7 -	Bearing shell

q	With oil drilling for piston pin lubrication

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

q	Bearing shells worn down to base layer must be renewed

q	Note installation position

8 -

Conrod

q	With oil drilling for piston pin lubrication

q	Only renew as a complete set

q	Mark cylinder allocation in colour -B-

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

q	Axial clearance (new): 0.10 ... 0.35 mm

q	Axial clearance (wear limit): 0.40 mm

q	Measuring radial clearance → Chapter

9 -

Circlip

q

Renew

10 -	Piston pin

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

q	Remove and install using drift -VW 222 A-

11 -	Piston rings

q	Offset gaps by 120°

q	Use piston ring pliers to remove and install

q	“TOP” must face towards piston crown

q	Measuring ring gap → Fig.

q	Measuring ring-to-groove clearance → Fig.

12 -

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

q	Checking cylinder bore → Fig.

13 -

Bolt

q

Renew

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. –  Check gap using feeler gauge.

Piston ring	new mm	Wear limit mm
1st compression ring	0.20 … 0.40	0.8
2nd compression ring	0.20 … 0.40	0.8
Oil scraper ring	0.25 … 0.50	0.8

Checking ring-to-groove clearance –  Clean annular groove of piston. –  Check gap using feeler gauge.

Piston ring	new mm	Wear limit mm
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

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: 0.04 mm. Nominal dimension → Chapter „Piston and cylinder dimensions“.

Checking cylinder bore –  Use an internal dial 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“.