Audi A8 2003 Workshop Manual page 106

Audi A8 2003 ➤
8-cylinder TDI engine (4.2 ltr. 4-valve common rail), mechanics - Edition 12.2013
Measuring ring-to-groove clearance
– Clean groove in piston before checking clearance.
Piston ring
Dimensions in mm
1st compression ring
2nd compression ring
Oil scraper ring
Checking piston
– Using a micrometer (75 ... 100 mm), measure approx. 10 mm
from the lower edge, perpendicular to the piston pin axis.
• Maximum deviation from nominal dimension: 0.04 mm.
Nominal dimension
⇒ "5.3 Piston and cylinder dimensions", page 102
Measuring cylinder bore
– Use 50 ... 100 mm internal dial gauge to take measurements
at 3 points in transverse direction -A- and longitudinal direction
-B-.
• Maximum deviation from nominal dimension: 0.08 mm.
Nominal dimension
⇒ "5.3 Piston and cylinder dimensions", page 102
Piston installation position and piston/cylinder allocation
– Use chalk or waterproof felt-tip pen to mark cylinder allocation
on piston crown.
Note
Do not use a centre punch or scriber, as this would damage the
coating of the piston crown.
Installation position:
• Arrows on piston crowns point to pulley end.
100
Rep. gr.13 - Crankshaft group
New Wear limit
0.120 ... 0.160
0.050 ... 0.090
0.030 ... 0.070
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with respect to the correctness of information in this document. Copyright by AUDI AG.
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