[Trak Ratt]

Did he have any thoughts on why it was running poorly and the "oil on the pistons?"

[Spike]

Dave, not sure if your tach was accurate or just bouncing when it showed you 8500RPM.
But, if you think you did hit 8500, you may want to investigate whether the extra acceleration of the piston/rod at those speeds would be enough to stretch the rod, rod botls, or force the bearings out of round. 8500 is a lot higher than 6500, so may represent stress higher than the rod/bearings were designed to withstand. So even if it runs you may have higher clearances than before, etc....is your oil pressure as high as it was prior when the engine warmed up? I'm just raising the question, I don't have the facts from Porsche. But you may want to investigate.

[Rennen]

Originally Posted by david riley

Did he have any thoughts on why it was running poorly and the "oil on the pistons?"

It was running poorly because of the #1 exhaust valve adjuster retaining nut coming off and the adjuster backing all the way out. I don't know about the little daub of oil in #6 but it didn't seem to smoke when I fired it up so maybe no biggie. I have to tear it back down to replace a valve cover stud and put new gaskets in so I'll re-scope #6 when I do that and see if there is anything in the cylinder now.

[Rennen]

Originally Posted by Spike

Dave, not sure if your tach was accurate or just bouncing when it showed you 8500RPM.
But, if you think you did hit 8500, you may want to investigate whether the extra acceleration of the piston/rod at those speeds would be enough to stretch the rod, rod botls, or force the bearings out of round. 8500 is a lot higher than 6500, so may represent stress higher than the rod/bearings were designed to withstand. So even if it runs you may have higher clearances than before, etc....is your oil pressure as high as it was prior when the engine warmed up? I'm just raising the question, I don't have the facts from Porsche. But you may want to investigate.

I didn't warm it all the way up because it was so freaking loud w/ the exhaust off, but the oil pressure was coming up just fine. I will talk to a pro about the over-rev to find out if there is anything else I need to be worried about assuming it contines to run fine. I need to re-drain the case & re-seal the valve covers properly before I even think about driving it.

[Noah]

You may have dodged a bullet, but IMHO you really can't listen to a 911 engine that is running without mufflers. It's too loud to hear whether the motor sounds right or not.

[}{arlequin]

why not just do leakdown and compression? isn't that how engines are diagnosed during ppi's?

[Rick V]

You will need to run the car up to operating temp to properly perform a leakdown test. Button it up, fire it up and see what you are facing. If it runs like crap, drop it.

[roundel]

I hope it runs well with the exhaust on, warms up nicely, and passes leak down and compression with flying colors. The lack of shiney on the half moons on the pistons does sound like you may have avoided the interaction of valves and pistons. I was always most afraid of floating valves causing the impact with an over rev. I would think that fractions of a second of over rev from a missed shift would have less impact on the crank and lower end than the valves unable to flutter that quickly.

[Eli]

Here's a clip of what my 964 sounded like after a similar experience at the track. Broken rocker arms, bent valves, etc...Ended up rebuilding both top and bottom.

SOUNDCLIP

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Good luck, hope it's something minor.

[SkipC]

Anyone,
Are there any symptoms of over-rev damage to the rods, bolts, and/or bearings ? Or, does the car run and sound fine until the rod lets go ?