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 cylinder allocation before removing -A-

q	Installation position: marking -B- faces towards pulley end (apply marking before removal if no marking is visible)

3 -	Bearing shells

q	Upper bearing shell with oil hole for piston pin lubrication

q	Installation position → Fig.

q	Renew used bearing shells

4 -

Conrod

q	Only renew as a complete set

q	Mark cylinder allocation before removing -A-

q	Installation position: marking -B- faces towards pulley end (apply marking before removal if no marking is visible)

q	Guided axially via piston

q	Measuring radial clearance → Chapter

5 -	Piston pin

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

q	Remove and install using drift -VW 222 A-

6 -

Circlip

q

Renew

7 -

Piston

q	Checking → Fig.

q	Mark installation position and cylinder number

q	Installation position: arrow on piston crown points to pulley end

q	Install using piston ring clamp

q	Measuring cylinder bore → Fig.

q	Piston and cylinder dimensions → Chapter

8 -	Compression ring

q	Pay attention to cross section

q	Offset gap by 120° to next compression ring

q	Use piston ring pliers to remove and install

q	Inscription „TOP“ faces towards piston crown

q	Measuring ring gap → Fig.

q	Measuring ring-to-groove clearance → Fig.

9 -	Compression ring

q	Pay attention to cross section

q	Offset gap 120° relative to adjacent oil scraper ring

q	Use piston ring pliers to remove and install

q	Inscription „TOP“ faces towards piston crown

q	Measuring ring gap → Fig.

q	Measuring ring-to-groove clearance → Fig.

10 -	Oil scraper ring

q

3 parts

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	Measuring ring gap → Fig.

q	Ring-to-groove clearance cannot be checked

Measuring 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. To do so, use a piston without rings.

Piston ring	new mm	Wear limit mm
1st compression ring	0.20 … 0.40	1.00
2nd compression ring	0.40 … 0.60	1.00
Oil scraper ring	0.20 … 0.80	No wear limit data available

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

Piston ring	new mm	Wear limit mm
1st compression ring	0.04 … 0.08	0.15
2nd compression ring	0.02 … 0.06	0.15
Oil scraper ring	Cannot be measured

Checking piston –  Using a micrometer (75 ... 100 mm), measure approx. 12 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“.   Note Do not mount cylinder block on engine and gearbox support -VAS 6095-, as incorrect measurements may result.

Installation position of bearing shells in conrods –  Insert bearing shells centrally in conrod/conrod bearing cap. l  Distance -a- = approx. 1.5 mm.

Oil spray jet and pressure relief valve 1 -  Bolt with pressure relief valve, 27 Nm 2 -  Oil spray jet for piston cooling l  Installation position: align locating edge of oil spray jet with machined surface of cylinder block.   Caution Avoid damage to oil spray jets. t  Do not bend oil spray jets. t  Always renew bent oil spray jets.