Audi TT (2007 year). Manual - part 22

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not 
 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability 
     with respect to the correctness of information in this document. Copyright by AUDI AG.

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

Piston ring

new

mm

Wear limit

mm

1st compression ring

0.06 … 0.09

0.25

2nd compression ring

0.05 … 0.08

0.25

Oil scraper ring

0.03 … 0.06

0.15

Checking piston
– Using a micrometer (75 ... 100 mm), measure approx. 15 mm

from the lower edge, perpendicular to the piston pin axis.

• Maximum deviation from nominal dimension: 0.04 mm.
Nominal dimension

⇒ “4.3 Piston and cylinder dimensions”, page 82

 .

Note

Renew piston if cracking is visible on piston skirt.

Installation position of pistons and allocation of piston/cylinder
• Arrow on piston crown points to pulley end -arrows-.

Measuring cylinder bore
– Use a cylinder gauge -VAS 6078- to take measurements at 3

points in transverse direction -A- and in longitudinal direction

-B-.

• Maximum deviation from nominal dimension: 0.10 mm.
Nominal dimension

⇒ “4.3 Piston and cylinder dimensions”, page 82

 .

4. Pistons and conrods    

79

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not 
 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability 
     with respect to the correctness of information in this document. Copyright by AUDI AG.

Installation position of bearing shells in conrods
1 - Bearing shell with oil drilling -arrow- for conrod.
2 - Bearing shell without oil drilling for conrod bearing cap.
– Position bearing shells in centre of conrod and conrod bearing

cap when fitting.

• Distance -a- is the same on both sides.

Separating parts of new conrod
It is possible that the two parts of a new conrod are not completely

separated as intended. If it is not possible to take off the conrod

bearing cap by hand, proceed as follows:
– To avoid any risk of damage, the conrod should only be clam‐

ped lightly in a vice using jaw covers as shown in illustration.

• The conrod is clamped in position below the dotted line.
– Unscrew bolts -arrows- approx. 5 turns.

– Using a plastic hammer, carefully knock conrod bearing cap

loose -arrow-.

Oil spray jet and pressure relief valve
1 - Bolt with pressure relief valve, 27 Nm
2 - Oil spray jet (for cooling of pistons)
• Installation position: align locating edge of oil spray jet with

machined surface of cylinder block.

Note

♦

Take care not to bend oil spray jets.

♦

Always renew bent oil spray jets.

80

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not 
 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability 
     with respect to the correctness of information in this document. Copyright by AUDI AG.

4.2

Measuring piston projection at “TDC”

Note

♦

Piston projection at “TDC” must be measured when installing

new pistons or a short engine.

♦

If the measured values for piston projection are not the same

for all pistons, use the highest value to determine the correct

gasket size.

♦

Depending upon piston projection, install the corresponding

cylinder head gasket according to the table below.

Special tools and workshop

equipment required
♦ Measuring bridge -

VW 382/7- from measuring

tool -VW 382-

♦ Measuring plate -

VW 385/17- from universal

measuring tool -VW 385-

♦ Dial gauge -VAS 6079-

4. Pistons and conrods    

81

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not 
 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability 
     with respect to the correctness of information in this document. Copyright by AUDI AG.

Procedure
– Secure dial gauge -VAS 6079- with measuring bridge -

VW 382/7- and measuring plate -VW 385/17- to cylinder block

as shown in illustration.

– Measure piston projection at two points marked with

-arrows- for each piston.

Piston projection above top sur‐

face of cylinder block

mm

Identification

(No. of holes)

0.91 … 1.00

1

1.01 … 1.10

2

1.11 … 1.20

3

Identification of cylinder head gasket
1 - Part number
2 - Holes
3 - Ignore

Note

If the measured values for piston projection are not the same for

all pistons, use the highest value to determine the correct gasket

size.

4.3

Piston and cylinder dimensions

Honing dimension

Piston ∅

mm

Cylinder bore ∅

mm

Basic dimension

80.96 

1)

81.01

•

1)

 Dimensions including coating (thickness 0.02 mm). The

coating will wear down in service.

4.4

Measuring radial clearance of conrods

Special tools and workshop equipment required
♦ Plastigage
Procedure
– Remove conrod bearing cap. Clean bearing cap and bearing

journal.

– Place a length of Plastigage corresponding to the width of the

bearing on the bearing journal or in the bearing shell.

82