audi r8 part1.pdf


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

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Atomisation of the injectors is not correct or leaking injectors



Injection pressure too low



Compression pressure too low – possibly caused by incorrect head gasket, piston rings etc



Use of starting aids (start sprays)



Use of non-approved fuel additives

1.4 Hydraulic Locks
Hydraulic locks can be caused by fluid entering the combustion chamber. This can be attributed
mainly to one of the points below:


Water from flood damage



Coolant entry due to other external influence (EGR cooler, head gasket, cracked bore etc)



Engine oil – customer may have expressed excessive oil use



Fuel – faulty injector for example

1.5 Installation errors
When the engine builder inserted the piston, they did not compress the rings correctly or knocked the
piston in rather than slid it into place. In this case, the ring land fracture is the opposite shape and
clearly indicates that it has moved in the upwards direction.

2.0 Removal of material from the piston crown and ring zone

In the case of material being removed from the piston crown and down to the piston rings (sometimes
behind the rings), this is caused by glow-ignition within the combustion chamber. Ultimately, parts
within the combustion chamber are glowing hotter than the flash point of the air/fuel ratio. These
components are likely to be the spark plugs, exhaust valve and areas of carbon build up on the piston
crown.
In this situation, it is often found that material has also been removed from the exhaust valve (intake
valve is fine due to the cooling effect of incoming air).

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

12/05/2015