No compression

2006 AUDI RS 4
95,000 MILES • 4.2L • V8 • 4WD • MANUAL
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ZIGGY266
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The inlet manifold on cylinder three the bolt had broken off and caused the bolt to fall into the engine where the piston is. The car was not driven as it was parked when I heard the noise and was not driven at all. There was no damage done as this was fully checked. However, it did leave a mark on the piston at the top only. After putting it back together one of cylinders number three had no compression.

Basically my question is cylinder three only has no compression what could this be?
Jul 1, 2018 at 4:43 PM
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JACOBANDNICKOLAS
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Hi and thanks for using 2CarPros.com.

If there is no compression, you must have bent a valve or damaged one and it is no longer sealing the compression in the cylinder. Even though you shut the engine down, you heard the problem and there was no way you could have shut it down quick enough. The damage was already done.

Take a look at this link. It discusses reasons for compression problems. If you page down to number 4, it discusses no compression in one cylinder.

https://www.2carpros.com/articles/the-reasons-for-low-compression

I do not like to say it, but chances are the cylinder head needs removed to inspect the valves. I have a feeling that is where the problem lies.

Let me know what you find or if you have other questions.

Take care,
Joe

Jul 2, 2018 at 5:53 PM