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How do you check a 997.2 for bore scoring?

 
Old 02-10-2019, 12:27 PM
  #1  
prairiedawg
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Default How do you check a 997.2 for bore scoring?

I'm in the market for a 997.2 Cab and am waiting for the right one to come along. I'm in the Chicago area and am somewhat limited to the local marketplace. I have been following Bronz's ordeal https://rennlist.com/forums/997-foru...e-failure.html especially closely as he is in the same area as myself. It sound like the mode of failure is bore scoring in his engine but Flat Six hasn't publicly stated the likely cause yet that I'm aware of. It sounds like there are a number of aggravating factors that contribute to this such as cold climate, ethanol in the fuel, DFI injectors leaking into the cylinders, and I'm sure others I have missed. It seems that any car within 500 miles would be subjected to some or all of these issues. After following these forums and reading all I can it looks like most of the issue starts at the bottom of the cylinder and will not present itself with a bore scope through the spark plug unless severe?

Seeing that a PPI is required before any purchase, I decided when the right one comes along I would simply pay extra to drop the pan and have the bottom of the cylinders examined. Imagine my surprise and horror to find that isn't the case: https://rennlist.com/forums/997-foru...der-check.html
A member Doclouie decided to be proactive and check his cylinders and found they weren't visible from underneath without removing a significant amount of parts to view. Nor is likely that an owner would authorize to disassemble all this as part of a PPI. I probably wouldn't!

Unless you're buying from a private owner who kept meticulous records and oil analysis', how can you tell if the engine is starting to or has bore scoring inside? Are there any telltale signs besides the carbon on the tail pipes? I know its a sign but everyone I've looked at in the last 6 months has some so either its just a common byproduct of combustion or they all have scored bores. If so that's a scary thought. Looking for some technical insight but any thoughtful answers are welcome. Hopefully Flat six will see this thread and chime in as well.
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Old 02-10-2019, 12:32 PM
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There are over 100 posts on this forum about this subject, just use the search tool and youll find answers and then some...
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Old 02-10-2019, 01:14 PM
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Here is what I have found out:

1. It is caused by piston slap breaking down the coating of the cylinder wall. That suggests a loss of compression may indicate a problem. But you probably wouldn't buy that car anyway.
2. Piston slap is due to rings being damaged by oil dilution due to cold weather operation for short distances and the use of E10 in the gas. I was told to use top tier fuels and an E10 additive and avoid short trips in cold weather.
3. The incidence of bore scoring in a 997.2 is quite low. Most of the postings about it are related to 997.1, so 997.2 threads are like finding a needle in a haystack.
4. Carbon on the tailpipe is not indicative of bore scoring.
5. What few verifiable reports of 997.2 bore scoring occurred in cold weather climates, but no indication given of how or when they were driven.
6. Buy a southern car and a drive train warranty... or don't drive short distance in cold weather.
7. Buy a sports car that doesn't have a horizontally opposed engine. (I'm leaning this direction).

Last edited by Balr14; 02-10-2019 at 01:45 PM.
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Old 02-10-2019, 01:45 PM
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There is almost no posts checking a 9A1 for bore scoring which is what this thread is about. There are scores (pardon the pun) of posts, threads on 997.1 scoring. If you are suggesting reading threads such as this one https://rennlist.com/forums/997-foru...liability.html I have done that and then some. The fact is if it happened to Bronz then it is happening to to others, they just don't know about it yet. While Bronz's situation may be an anomaly I doubt it. Jake Raby while not outright saying it has inferred that this isn't as uncommon as one would like to believe.

Besides my question isn't what causes or how to avoid it, it is how can a PPI verify that it isn't happening. I think this is a fair question that hasn't been answered to my knowledge. If it has, feel free to enlighten me. I'm asking if/when the right car comes along I want to insist the PPI mechanic does X to look for Y, especially now that I realize the cylinders cannot be seen from dropping the pan like on a M97.
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Old 02-10-2019, 01:59 PM
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I don't think there is any way outside of a compression test that would show that bore scoring could occur soon. None of the posts I read about the 997.2 indicated bore scoring was observed BEFORE the engine exhibited significant signs of failure.
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Old 02-10-2019, 02:32 PM
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Originally Posted by Balr14 View Post
I don't think there is any way outside of a compression test that would show that bore scoring could occur soon. None of the posts I read about the 997.2 indicated bore scoring was observed BEFORE the engine exhibited significant signs of failure.
That's the problem, I'm looking for technical advise to disclose it before the symptoms. I'm assuming by the time symptoms appear the scoring is likely significant and then too late to avoid the purchase. I suppose the compression test may be the only way but doesn't guarantee it's not occurring. I would think scoring could occur and still have compression values within spec. Besides,full compression occurs at TDC while the scoring in the early stages starts at the bottom of the cylinder where the piston skirts may be contacting the cylinder walls. This could start below the rings and not affect compression at all in the beginning stages if I'm thinking clearly about this.
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Old 02-10-2019, 02:39 PM
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Originally Posted by prairiedawg View Post
There is almost no posts checking a 9A1 for bore scoring which is what this thread is about. There are scores (pardon the pun) of posts, threads on 997.1 scoring. If you are suggesting reading threads such as this one https://rennlist.com/forums/997-foru...liability.html I have done that and then some. The fact is if it happened to Bronz then it is happening to to others, they just don't know about it yet. While Bronz's situation may be an anomaly I doubt it. Jake Raby while not outright saying it has inferred that this isn't as uncommon as one would like to believe.

Besides my question isn't what causes or how to avoid it, it is how can a PPI verify that it isn't happening. I think this is a fair question that hasn't been answered to my knowledge. If it has, feel free to enlighten me. I'm asking if/when the right car comes along I want to insist the PPI mechanic does X to look for Y, especially now that I realize the cylinders cannot be seen from dropping the pan like on a M97.
Well stated. Waiting to hear from Jake or someone who can articulate an answer to your question.
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Old 02-10-2019, 02:55 PM
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Cylinder scoring is not as a result of cylinder coating peeling off, but rather as a result of the piston coating flaking and thus scoring the cylinder. It normally happens in cylinder 6. There has been articles going in depth as to why it happens on cylinder 6. At this point on the 9A1 engine and very odd case of it happening, nobody knows why it happens. FST is currently dissecting a 9A1 engine and is at an investigating stage.
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Old 02-10-2019, 03:10 PM
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Just find a nice well documented car, get a standard PPI, drive the car and forget about it! One person has an engine failure and you got guys dropping oil pans and obsessing over checking for scoring now.
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Old 02-10-2019, 04:32 PM
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For those of you who did not see my post about checking a bore on a 997.2. Here is a picture of what the bottom of the engine looks like. Lots to remove before you can see much and yes you will need a camera snake to see it.

As for bore scoring. Listen to the expert and subscribe to his channel.

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Old 02-10-2019, 06:25 PM
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I can provide some context on my experience with bore scoring on a 997.2 3.6L.

I bought a northern car that spent it's first 20K miles in the NY/Philly area and bought it as a CPO. Advice was given to me when I started shopping to insure that I only bought a CPO car (I have to thank George who used to work for Kanon Best, as you Raleigh folks will know these guys for that advice).

On my maiden trip back from Philly to NC the oil light came on when I crossed the NC state line and found the first Wal-mart I could to get several quarts of Mobil 1 and filled it up. I took for granted when I bought the car the oil was topped off. I did speak with the dealership shortly after and their response was "Hmm. that is odd..."

Based on this I recorded every drop of oil in a spreadsheet that I had to add and determined I was putting about a 1/2 quart of oil in approximately every 500 miles. After I drove the car for about a year, and from getting more knowledge under my belt from these forums I decided to call my local dealership and explain the situation since I was under CPO. I did not have any discernible symptoms other than high oil consumption and equally sooty muffler tips and a gnawing hunch there was something else going on. They did a fantastic job and agreed they would like for me to bring in the car and run some diagnostics. I did that and they did see some results from manometer readings that indicated replacing the AOS. They did this and I drove the car another 1k miles and had to add another full quart. At this point I did notice a slight uptick in throttle performance, though still had concerns with the continued high oil consumption.

They then took the car in and said they would do a full diagnostic, drop the engine, do a leak down and compression test and a bore scope. They did all of this, the leak down and compression came back fine however the bore scope did see scoring on cylinder 0 if I recall correctly. They took the results and consulted with Porsche AG and it was decided I would get a brand new 997.2 3.6L engine from Germany all under CPO and no out of pocket for me. This process took about 5 weeks if I recall correctly constituted a Major Service (naturally I got new motor mounts, plugs and coil packs with the new engine)

So to recap, I had bore scoring with only 25K miles on the car. I have some paperwork on previous maintenance though very little as tracking down some of the maintenance as some of the dealership was futile and they were actually rude about it. All I knew was I was the 3rd owner and the previous 2nd owner was a dealership sales person who had owned the car for about a year and a half. Maybe they know the oil consumption was an issue, maybe not....

Since I have received the car back in Sept of 2016, I have insured everything is done right. I did a burn in oil change after about 800 miles and I only take the car out when I know it will get properly warmed up and rarely drive it when it is under 35 degrees.

Also since I have had the car back, I have not added a drop of oil in it whatsoever, knock on wood, and only get it serviced at Road Scholars for my annual service. The engine was replaced at 26K miles and I now have 33K miles on the odometer. I know, I should drive it more...

The point of all of this is to let folks it can and will happen as some folks say 997.2 scoring is very rare. Maybe, but it happened with me. The next time I buy I will only buy CPO and will get a PPI with a bore scope (as I neglected to get the PPI and bore scope since I got the CPO) I know better now....however....

I also spoke to Jake earlier in January to do my due diligence on my future options for a pre-emptive mitigation. I am very grateful that Jake took the time to speak with me and consult and present a recommendation. I wanted to know straight from the horse's mouth what my options were as his website mentioned a 3.6 may be made in to a 4.0 and I wanted to validate that. At this point, however the pragmatic side of me says it makes no sense to me to spend $X to perform this mitigation when I only have about 7k miles on the new motor. It has however put in perspective for me that it will most likely be a goal for me to do in the next few years since I now know the full provenance of my car with the new engine and I'm happy with what I have and I would rather put $X in my existing car than go through the process of buying another vehicle whose provenance will need to be scrutinized...Also the thought of making my base 3.6 have near the performance of a GTS is quite enticing...

Feel free if anyone has any questions to PM me. I'll be glad to provide more details....TL/DR. Get a PPI and a borescope before you buy and if possible only buy CPO....
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Old 02-10-2019, 06:41 PM
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Originally Posted by doclouie View Post


For those of you who did not see my post about checking a bore on a 997.2. Here is a picture of what the bottom of the engine looks like. Lots to remove before you can see much and yes you will need a camera snake to see it.

As for bore scoring. Listen to the expert and subscribe to his channel.

https://youtu.be/dzDerJOdcfI
Thanks for posting the picture, that's what started this thread. I was going to ask this in your thread but decided I didn't want to hijack yours and its important enough to support its own thread. This picture made my heart sink when i saw it as I realized checking the bottom of the bore was probably not possible without being too intrusive for a PPI.
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Old 02-10-2019, 07:04 PM
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Originally Posted by gopirates View Post
I can provide some context on my experience with bore scoring on a 997.2 3.6L.

I bought a northern car that spent it's first 20K miles in the NY/Philly area and bought it as a CPO. Advice was given to me when I started shopping to insure that I only bought a CPO car (I have to thank George who used to work for Kanon Best, as you Raleigh folks will know these guys for that advice).

On my maiden trip back from Philly to NC the oil light came on when I crossed the NC state line and found the first Wal-mart I could to get several quarts of Mobil 1 and filled it up. I took for granted when I bought the car the oil was topped off. I did speak with the dealership shortly after and their response was "Hmm. that is odd..."

Based on this I recorded every drop of oil in a spreadsheet that I had to add and determined I was putting about a 1/2 quart of oil in approximately every 500 miles. After I drove the car for about a year, and from getting more knowledge under my belt from these forums I decided to call my local dealership and explain the situation since I was under CPO. I did not have any discernible symptoms other than high oil consumption and equally sooty muffler tips and a gnawing hunch there was something else going on. They did a fantastic job and agreed they would like for me to bring in the car and run some diagnostics. I did that and they did see some results from manometer readings that indicated replacing the AOS. They did this and I drove the car another 1k miles and had to add another full quart. At this point I did notice a slight uptick in throttle performance, though still had concerns with the continued high oil consumption.

They then took the car in and said they would do a full diagnostic, drop the engine, do a leak down and compression test and a bore scope. They did all of this, the leak down and compression came back fine however the bore scope did see scoring on cylinder 0 if I recall correctly. They took the results and consulted with Porsche AG and it was decided I would get a brand new 997.2 3.6L engine from Germany all under CPO and no out of pocket for me. This process took about 5 weeks if I recall correctly constituted a Major Service (naturally I got new motor mounts, plugs and coil packs with the new engine)

So to recap, I had bore scoring with only 25K miles on the car. I have some paperwork on previous maintenance though very little as tracking down some of the maintenance as some of the dealership was futile and they were actually rude about it. All I knew was I was the 3rd owner and the previous 2nd owner was a dealership sales person who had owned the car for about a year and a half. Maybe they know the oil consumption was an issue, maybe not....

Since I have received the car back in Sept of 2016, I have insured everything is done right. I did a burn in oil change after about 800 miles and I only take the car out when I know it will get properly warmed up and rarely drive it when it is under 35 degrees.

Also since I have had the car back, I have not added a drop of oil in it whatsoever, knock on wood, and only get it serviced at Road Scholars for my annual service. The engine was replaced at 26K miles and I now have 33K miles on the odometer. I know, I should drive it more...

The point of all of this is to let folks it can and will happen as some folks say 997.2 scoring is very rare. Maybe, but it happened with me. The next time I buy I will only buy CPO and will get a PPI with a bore scope (as I neglected to get the PPI and bore scope since I got the CPO) I know better now....however....

I also spoke to Jake earlier in January to do my due diligence on my future options for a pre-emptive mitigation. I am very grateful that Jake took the time to speak with me and consult and present a recommendation. I wanted to know straight from the horse's mouth what my options were as his website mentioned a 3.6 may be made in to a 4.0 and I wanted to validate that. At this point, however the pragmatic side of me says it makes no sense to me to spend $X to perform this mitigation when I only have about 7k miles on the new motor. It has however put in perspective for me that it will most likely be a goal for me to do in the next few years since I now know the full provenance of my car with the new engine and I'm happy with what I have and I would rather put $X in my existing car than go through the process of buying another vehicle whose provenance will need to be scrutinized...Also the thought of making my base 3.6 have near the performance of a GTS is quite enticing...

Feel free if anyone has any questions to PM me. I'll be glad to provide more details....TL/DR. Get a PPI and a borescope before you buy and if possible only buy CPO....
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.

Last edited by prairiedawg; 02-10-2019 at 07:35 PM.
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Old 02-10-2019, 07:21 PM
  #14  
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I wouldn't buy any car that spent it's life in the Chicago area. I have been burned every time I did.
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Old 02-10-2019, 07:24 PM
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I've vowed to only do sun belt cars from now on simply due to rust and corrosion, let alone bore issues.
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