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How do you check a 997.2 for bore scoring?

 
Old 02-10-2019, 07:50 PM
  #16  
gopirates
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Originally Posted by prairiedawg View Post
Thank you for sharing you experience and I'm glad everything worked out for you. This just shows that what happened to Bronz is not a one off event and is likely much more common than realized. 25K on an engine is still new unless it was tracked as far as I'm concerned. This is what bothers me about buying one without a warranty and even a CPO is only two years. Scoring could easily develop and not present symptoms until well after the warranty has expired. "They did all of this, the leak down and compression came back fine" This raises concerns with a PPI. This kind of confirms that a compression test can come back normal and still have early or even severe scoring with little to no symptoms.
How severe was the scoring and which cylinder was affected? How much of the damage was revealed by the bore scope? I'm curious if this will be the same cylinder as Bronz? I don't subscribe to the theory of just buy a well sorted car and hope for the best. 25K miles and a CPO to boot sounds well sorted to me.
I try to be an educated consumer no matter what I buy and just want to be sure I don't purchase the wrong 911.
Pretty sure my car was not tracked. If so, it was done by a grandma based on the DME report I was provided. I also requested a new DME report with the new engine as a reference point if I have to sell the car down the road (as a point in time datapoint after the new install) and it confirmed these overrevs were the same from my recollection.

Number of ignitions at speed > maximum speed, range 1 261
Operating hours counter reading at overspeed, range 1 543.73 h
Number of ignitions at speed > maximum speed, range 2 0
Operating hours counter reading at overspeed, range 2 0.00 h
K040_Test counter for c.c. diagnosis b1 0
K050_Test counter for c.c. diagnosis b2 0
M120_Misfire counter for every ignition 10562
Number of ignitions at speed > maximum speed, range 3 0
Operating hours counter reading at overspeed, range 3 0.00 h
Number of ignitions at speed > maximum speed, range 4 0
Operating hours counter reading at overspeed, range 4 0.00 h
Number of ignitions at speed > maximum speed, range 5 0
Operating hours counter reading at overspeed, range 5 0.00 h
Number of ignitions at speed > maximum speed, range 6 0
Operating hours counter reading at overspeed, range 6 0.00 h
Operating hours counter 563.53 h


As far as scoring, I just reviewed the email threads I had with the dealership and it was cylinder #1 that showed the scoring. They said it was light scoring, though scoring nonetheless and enough to warrant for engine replacement under CPO.
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Old 02-10-2019, 08:07 PM
  #17  
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The leak down and compression test for my 2008 997.1 C2S came back "normal" as well, even after I suspected a problem, which also ultimately turned out to be a scored bore in cylinder #6. I recognize it is completely different from a 9A1 engine, but it is quite true that these two tests don't necessarily tell you anything about scored bores. I also did not get any indication about the problem with my oil analyses until after I already knew for sure I had a scored bores.

I would not at all be afraid to buy a 997.2, but one way or another, I would have the bores scoped through the top AND sump. And I would pay close attention to what Charles Navarro and Jake Raby say about what they are finding and how they recommend maintaining it. I also would not be afraid of buying a well-cared-for 997.1 rebuilt to their standards or with a replacement RND engine.

CPO and other extended warranties are probably a good idea, but they will always require the engine to be replaced with another OEM engine with potentially the same problems. So once the very thorough PPI was done and the sale consummated, I would put away the same amount of money such a warranty would cost, and add another 5%-10% to this fund each month to partially defray the cost of a proper Raby rebuild eliminating known risks. Then, if Murphy's Law holds true, you will never have an engine problem, but you will end up with a very nice down payment on your next Porsche. But that's just me. Everybody has their own unique tolerance to risk.
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Old 02-10-2019, 08:38 PM
  #18  
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Originally Posted by JustinCase View Post
I would have the bores scoped through the top AND sump.
It doesn't appear to be feasible to scope through the sump.
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Old 02-10-2019, 08:57 PM
  #19  
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Originally Posted by gopirates View Post
Pretty sure my car was not tracked. If so, it was done by a grandma based on the DME report I was provided. I also requested a new DME report with the new engine as a reference point if I have to sell the car down the road (as a point in time datapoint after the new install) and it confirmed these overrevs were the same from my recollection.

Number of ignitions at speed > maximum speed, range 1 261
Operating hours counter reading at overspeed, range 1 543.73 h
Number of ignitions at speed > maximum speed, range 2 0
Operating hours counter reading at overspeed, range 2 0.00 h
K040_Test counter for c.c. diagnosis b1 0
K050_Test counter for c.c. diagnosis b2 0
M120_Misfire counter for every ignition 10562
Number of ignitions at speed > maximum speed, range 3 0
Operating hours counter reading at overspeed, range 3 0.00 h
Number of ignitions at speed > maximum speed, range 4 0
Operating hours counter reading at overspeed, range 4 0.00 h
Number of ignitions at speed > maximum speed, range 5 0
Operating hours counter reading at overspeed, range 5 0.00 h
Number of ignitions at speed > maximum speed, range 6 0
Operating hours counter reading at overspeed, range 6 0.00 h
Operating hours counter 563.53 h


As far as scoring, I just reviewed the email threads I had with the dealership and it was cylinder #1 that showed the scoring. They said it was light scoring, though scoring nonetheless and enough to warrant for engine replacement under CPO.
Thanks for adding to the discussion. It looks like yours would have been an ideal purchase and the proverbial cream puff. Scary when you cannot discern the maintenance history. Makes the Carmax 5yr/60k warranty look better and better. Too bad the cars aren't the cream of the crop.
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Old 02-10-2019, 09:37 PM
  #20  
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My experience is documented here with a thread I started back in 2016 about oil consumption. Jake weighed in then and also was very helpful and consultative in the fact that the leak down and compression tests would yield no results that would really be very deterministic from my recollection.
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Old 02-10-2019, 10:19 PM
  #21  
Dennis R. Cliff
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My 2009 C2S coupe had thick, fuzzy, soot deposits in the tailpipe tips as well as in the actual exhaust ports pre-cat. As the engine management aspects of the car's computer can be assumed to insure optimal air fuel ratios, I feared bore scoring. I bought a borescope off of Ebay, removed the mufflers and spark coils, took pictures at or near BDC and decided that the engine had no bore scoring. These engines have short strokes and the pistons don't have long skirts, so I am thinking that bore scoring to a degree that you are going to get symptoms will probably show up at BDC. It turned out that the PO of my car had over filled the oil by about eighteen ounces hence all the unburned carbon. Now with the correct oil level and new spark plugs there is next to no soot. I think that we have to wait for the report and videos from Flat six innovations to get to the causes of bore scoring. Checking the bores with a scope isn't that difficult.
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Old 02-11-2019, 10:57 AM
  #22  
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Originally Posted by prairiedawg View Post
Thank you for sharing you experience and I'm glad everything worked out for you. This just shows that what happened to Bronz is not a one off event and is likely much more common than realized. 25K on an engine is still new unless it was tracked as far as I'm concerned. This is what bothers me about buying one without a warranty and even a CPO is only two years. Scoring could easily develop and not present symptoms until well after the warranty has expired. "They did all of this, the leak down and compression came back fine" This raises concerns with a PPI. This kind of confirms that a compression test can come back normal and still have early or even severe scoring with little to no symptoms.
How severe was the scoring and which cylinder was affected? How much of the damage was revealed by the bore scope? I'm curious if this will be the same cylinder as Bronz? I don't subscribe to the theory of just buy a well sorted car and hope for the best. 25K miles and a CPO to boot sounds well sorted to me.
I try to be an educated consumer no matter what I buy and just want to be sure I don't purchase the wrong 911.
You can never be sure that any used car wont have a failure. if engine concerns are your primary, but a turbo or gt3. the 9a1 is a solid motor, particularly compared to the m96/m97. if thats not good enough for you, you need to look at a different car
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Old 02-11-2019, 11:30 AM
  #23  
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If I want to educate myself and be prepared to conduct a PPI to catch a catastrophic failure before purchasing then I shouldn't join your club. Thanks.

I'm starting to understand why Jake Raby doesn't want to discuss these engines publicly.
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Old 02-11-2019, 11:49 AM
  #24  
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Originally Posted by prairiedawg View Post
If I want to educate myself and be prepared to conduct a PPI to catch a catastrophic failure before purchasing then I shouldn't join your club. Thanks.

I'm starting to understand why Jake Raby doesn't want to discuss these engines publicly.
no, people have explained to you the issues with conducting in depth PPIs on this motor with respect to borescoping.

additionally, just because the bores aren't scored when you buy it doesn't mean they won't score after the fact.

You seem to want a guarantee that you won't have issues with the motor and that will not happen.

Either you have to be ok with the very slim chance that your 9A1 fails or you have to look towards other cars. There is only so much mitigation for risk that can happen. A PPI is just a snapshot at a very specific time.
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Old 02-11-2019, 12:07 PM
  #25  
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Just goes to show 997.1 or .2 although less frequent .... **** can happen ..at the end of the day all mass produced products be it cars or dishwashers will have a small percentage of failures.

All industries will not speak to it directly but part of my prior job occupation was tracking (SIR) failure incident rates as we call it for a major retailer and i can tell you the target failure rate is always less than 2% incident rate, and almost all brands never achieve this low rate other than electronic merchandise.

The average failure rate for any "mechanical product" is anywhere from 8-10% on average and would be considered acceptable.
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Old 02-11-2019, 01:38 PM
  #26  
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Originally Posted by rileyracing1 View Post
Just goes to show 997.1 or .2 although less frequent .... **** can happen ..at the end of the day all mass produced products be it cars or dishwashers will have a small percentage of failures.

All industries will not speak to it directly but part of my prior job occupation was tracking (SIR) failure incident rates as we call it for a major retailer and i can tell you the target failure rate is always less than 2% incident rate, and almost all brands never achieve this low rate other than electronic merchandise.

The average failure rate for any "mechanical product" is anywhere from 8-10% on average and would be considered acceptable.
Agree with you. Even new cars have problems. The difference is that you have warranty. Even than, at times it happens that they cannot fix it and under law would have to replace the car.
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Old 02-11-2019, 03:09 PM
  #27  
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So what, if anything can be done to mitigate the chances of scoring in the 997.2? Anything in additon to proper warm up?
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Old 02-11-2019, 04:06 PM
  #28  
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Originally Posted by rileyracing1 View Post
Just goes to show 997.1 or .2 although less frequent .... **** can happen ..at the end of the day all mass produced products be it cars or dishwashers will have a small percentage of failures.

All industries will not speak to it directly but part of my prior job occupation was tracking (SIR) failure incident rates as we call it for a major retailer and i can tell you the target failure rate is always less than 2% incident rate, and almost all brands never achieve this low rate other than electronic merchandise.

The average failure rate for any "mechanical product" is anywhere from 8-10% on average and would be considered acceptable.
Very much agreed, if cars didnĺt break people wouldnĺt make a good living as a mechanic. The whole response to an engine failure on this forum is quite entertaining!
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Old 02-11-2019, 04:14 PM
  #29  
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What I am interested in finding out; is the occurrence of bore scoring in the 997.2 the result of issues in the design and production of the motors by Porsche or is bore scoring the result of driver practices and other circumstances that an engine is subjected to after it is purchased new from a dealer. Air cooled Porsche engines are generally described as "bullet proof". Buyers generally have no qualms about buying high mileage air cooled cars. In my opinion, the engines in 1999 to 2008 cars are certainly not "bullet proof", excepting Mezgers. So might there be bad batches of pistons going into some .2s or variations in the coating process for the pistons? The cylinder bores supposedly do not wear out, The coating of pistons with a tough, friction reducing, wear resistant silicone compound is fairly old and common technology. Engine design and manufacture is Porsche's forte. They build racing engines!!!. So even if an owner of one of these cars doesn't maintain his car properly and tends to run the Beejesus out of it I would hope that the engine isn't so delicate as to develop scored bores. I am tending to suspect that the bore scoring problem is due to the design and production of these motors and to a lesser degree the fault of owners practices or air temps. I suppose we will eventually find out.
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Old 02-11-2019, 04:15 PM
  #30  
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On Jake's video on the other post from Bronze, he shows the number 1 spark plug and it looks very oily compared to the other 5, and this is the plug from the affected cylinder with scoring. i wonder if there is any correlation. I would think that scoring would allow oil to bypass and contaminate the plugs, but that is pure conjecture on my behalf. Not too hard to pull spark plugs on a PPI and check for unusual excess oil in the spark plug.
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