audi r8 part1.pdf


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Engine Component Damage (UK TPI)(2029773/4)

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In the case of impact marks on the piston crown and cylinder head, it’s important to check the vehicle
history and observe areas of the intake system that may have had parts dislodged (turbo/EGR/throttle
valve etc).
In some cases, it’s found that there is material washout around the ring groove area. This is a result
of debris becoming lodged in the ring groove which causes abrasion to the area surrounding the
piston ring.

3.1 Possible causes


New engine fitted but parts of damaged engine not cleaned out of the intake/exhaust system



Parts of the intake system have broken off and entered the combustion chamber
(turbo/EGR/throttle valve etc)



Parts within the combustion chamber broken off (glowplug/spark plug/injector)



Incorrect valve timing



Incorrect valve clearance (wrong cylinder head gasket or excessive piston protrusion)



Engine over-revved (valves no longer close in time and impact on the piston crown)



Excessive clearances in the conrod bearings leading to excessive piston protrusion

4.0 Erosion of material from the top of the piston land and crown

The top of the piston land and crown show evidence of material being carried away in an erosion type

file:///D:/ElsaWin/docs/hs2/A/en-GB/src/2b/714283/master.htm

12/05/2015