Engine Failure

I posted this on Pelican also and it was recommended I come here. Thanks in advance for any help you can give me. I am now driving a Porsche 997.1 from 2008. Or, at least, I was. Suddenly there was a huge amount of smoke and rough idling upon start up so I shut it off and it was taken to my local Porsche mechanic (certified and years of experience). Upon tear down there was oil in the third cylinder and a bent rod. There was also slight oil in the other cylinders but #3 was the worst. We assumed it was the air-oil separator. However, upon tearing open the AOS we found it looked perfectly normal inside and the diaphragm was intact! The engine was never overfilled with oil. It has been maintained according to the manual. No problems up to this point. No major work ever done. I have full records going back to the original sale, one owner. My question is this: what else could cause oil to get into the cylinders besides the AOS? Also, the cylinders were ovalized, out of round. Could this be a cause of oil leaking into the cylinder? Could it be something with the intake manifold? Anything else??? Again, thanks. I'm going to have to rebuild the engine but would like to know what caused it.

Had you recently added ANY oil? If the oil was overfilled and the AOS evacuated a big gob of oil from the crankcase to the engine, that's one way enough oil could be introduced into the cylinder to cause damage. I know you stated that it has never been overfilled, but... Your initial post doesn't say whether you were driving along happily and this suddenly happened or if this occurred just after starting the car. Had the car been sitting for days, or were you in the middle of a drive, or... ? Sorry for the loss.

I had just started the car and was pulling out of my garage. I have never added oil to the engine since it hasn't needed it. Planet 9 shows a technical white paper that details the history of the engines and the reason for uneven cooling of cylinders leading to ovalization of the cylinders and eventually oil getting up into the combustion chamber causing hydrolock. I'm wondering if that could have happened?

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What are the #3 cylinder's bore readings? I'm wondering how oval was the cylinder? Barring ovality producing a gap between the piston and its rings and the cylinder big enough to drive a truck through I am having a tough time removing the AOS from the #1 suspect position.

Thanks for your reply. I don't have the numbers at hand but will find out and post them. They were significantly off. It does seem that the AOS is involved but it appears normal. It couldn't be tested on the car because we were afraid to start it and do more damage. If I can prove something besides the AOS then my aftermarket warranty may cover part of the cost.

Hope your car gets sorted out. Best of luck.

Thanks. It will be expensive. Ill bore out the cylinders, new sleeves and probably new pistons and rods, IMS solution, new AOS and lots of other fixes to try to prevent another failure.

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^$15 - 20k job^ If you're lucky... Ouch! Best of luck with the prognosis and any necessary repairs

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sounds like a call to Jake is worth looking into with this price tag?

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FYI, sleeving these engines with cast iron liners is not advised, IIRC what Jake Raby has to say on the subject.

Thanks. Which liners are best?

I've heard of engines with bad bore scoring with loads of piston slap tapping like hell but still no compression loss or oil burning having been tracked to death I can't see ovality causing oil in your cylinders it's got to be in the induction side!!

Do you have any photos that I can review? You have lots to study, and learn before pulling the trigger. Remember: Failure is the opportunity to begin again, but more intelligently.