997.2 3.8 Engine Failure
02-14-2019, 07:13 AM
#436
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That piston has detonation written all over it. Preignition blowby to be exact. Faulty injector or bad fuel is the cause.
When this occurs, air/fuel mixture ignites on compression stroke. Piston is compressing burning mixture and high pressure flows past piston rings.
Temperature of the flowing/burning gasses is so high that it melts the piston, and the rings.
So the piston failure has nothing to do with engine oil.
When this occurs, air/fuel mixture ignites on compression stroke. Piston is compressing burning mixture and high pressure flows past piston rings.
Temperature of the flowing/burning gasses is so high that it melts the piston, and the rings.
So the piston failure has nothing to do with engine oil.
Last edited by speed rII; 02-14-2019 at 07:15 AM. Reason: typo
02-14-2019, 07:49 AM
#437
A lot of the concern amongst the community seems to be how to avoid a rebuild. My experience is at best anecdotal, but we're currently in the midst of a major atmospheric river and the wind is blowing the oaks on the heavily running creek alongside the house to the point that we're not sleeping tonight. I need a distraction so here goes ...
I took stewardship of my 2010 C4S PDK basically stock two radiator car at 35K miles 4.5 years ago and am now at 120K miles.
I've changed oil every 5K miles using only Mobil One 0-40. It's always been 7.5 quarts out and 7.5 quarts in with no addition in between changes. I run with the oil down one to two bars to allow for thermal expansion.
The car has been a San Francisco Bay Area vehicle its entire life (moderate climate).
It takes 10 freeway miles to get the oil up to 190 to 200 F on a normal day (60 to 90 F ambient with dry air). From what I've read, this seems to be fairly typical for the 997.2.
IMHO temperature control on the 9A1 has always been a problem. I took it out yesterday to play in the 45 F rain and couldn't get the oil past 175 (so my play was limited to low rpm operation only). Summer days playing in mountain passes can see the oil reach 275 F.
Most of my trips allow a full warm up, but there are the occasional Home Depot drives that are ten miles total back and forth.
From things Baz has said in the past if the oil is under 190 F I don't go over 3500 rpm. I also wait ten minutes after reaching 190 F before pushing the rpms. I'm not saying this is right or wrong. It's just what I've always done.
Interviewing the seller, he behaved in the same manner.
So far so good. I believe in Baz's warm up advice.
Others may liken the slow warm up to the LTT addition in the 997.1 cars, per Jake. Maybe Porsche took that idea and the 9A1 reflects the more gradual warm up. I can't help but feel the slower thermal expansion is less stressful. Thus, contrary to my thermodynamic understandings, and due to Petza's insistence, I believe in the LTT theory for the 997.1.
Anyway, mine is a single case only. This is the most reliable car I've ever owned, and that says a lot to me ... again IMHO.
BTW, atmospheric river (AR) is the West Coast term for these winter storms coming across the ocean carrying incredible amounts of moisture. This one has been a doozie. The wind gusts dropping off the hill behind the house have got to be near three digits.
Yesterday's drive saw lots of waterfalls coming down the hills and the roads were definitely outrageous. These cars truly perform wonderfully in these conditions.
I took stewardship of my 2010 C4S PDK basically stock two radiator car at 35K miles 4.5 years ago and am now at 120K miles.
I've changed oil every 5K miles using only Mobil One 0-40. It's always been 7.5 quarts out and 7.5 quarts in with no addition in between changes. I run with the oil down one to two bars to allow for thermal expansion.
The car has been a San Francisco Bay Area vehicle its entire life (moderate climate).
It takes 10 freeway miles to get the oil up to 190 to 200 F on a normal day (60 to 90 F ambient with dry air). From what I've read, this seems to be fairly typical for the 997.2.
IMHO temperature control on the 9A1 has always been a problem. I took it out yesterday to play in the 45 F rain and couldn't get the oil past 175 (so my play was limited to low rpm operation only). Summer days playing in mountain passes can see the oil reach 275 F.
Most of my trips allow a full warm up, but there are the occasional Home Depot drives that are ten miles total back and forth.
From things Baz has said in the past if the oil is under 190 F I don't go over 3500 rpm. I also wait ten minutes after reaching 190 F before pushing the rpms. I'm not saying this is right or wrong. It's just what I've always done.
Interviewing the seller, he behaved in the same manner.
So far so good. I believe in Baz's warm up advice.
Others may liken the slow warm up to the LTT addition in the 997.1 cars, per Jake. Maybe Porsche took that idea and the 9A1 reflects the more gradual warm up. I can't help but feel the slower thermal expansion is less stressful. Thus, contrary to my thermodynamic understandings, and due to Petza's insistence, I believe in the LTT theory for the 997.1.
Anyway, mine is a single case only. This is the most reliable car I've ever owned, and that says a lot to me ... again IMHO.
BTW, atmospheric river (AR) is the West Coast term for these winter storms coming across the ocean carrying incredible amounts of moisture. This one has been a doozie. The wind gusts dropping off the hill behind the house have got to be near three digits.
Yesterday's drive saw lots of waterfalls coming down the hills and the roads were definitely outrageous. These cars truly perform wonderfully in these conditions.
02-14-2019, 08:25 AM
#438
That piston has detonation written all over it. Preignition blowby to be exact. Faulty injector or bad fuel is the cause.
When this occurs, air/fuel mixture ignites on compression stroke. Piston is compressing burning mixture and high pressure flows past piston rings.
Temperature of the flowing/burning gasses is so high that it melts the piston, and the rings.
So the piston failure has nothing to do with engine oil.
When this occurs, air/fuel mixture ignites on compression stroke. Piston is compressing burning mixture and high pressure flows past piston rings.
Temperature of the flowing/burning gasses is so high that it melts the piston, and the rings.
So the piston failure has nothing to do with engine oil.
On another note, I find it comical how insecure some people seem to be in their choice of vehicle. If someone even suggests their may be flaws, there is instant push back and defensiveness. Quoting others opinions like if they do it enough times it somehow protects them from catastrophic failure. News flash, the pope could bless your engine and if it wants to take a dump, it is going to do it regardless! Whether a 997.1 or 997.2, we are all pretty fortunate to own such great vehicles! Live life, enjoy the car, and look at things like this with a completely open mind and possibly an opportunity to learn something.
02-14-2019, 09:09 AM
#439
Reading this and the other thread on the same topic is extremely frustrating.
I suppose people think I must be lying when I say we measured the bores that have seized (not scored) and the adjacent ones and found clearances shrunk down to less than half a thou in the areas either side of the centre thrust direction where the piston has seized (and that after over 70K and pistons also worn down a little) the next cylinder half that shrinkage and the last one no shrinkage.
They cannot have been made like that or the engines would not have lasted for over 70K.
It is entirely illogical not to understand that something has caused the clearances at the bottom of some cylinders to shrink inwards in the area immediately in line with the large section casting that also holds the main bearings.
It is also illogical when told that all 5 seized in winter and after a very short distance driving admittedly fast from cold - all sorts of other explanations that have no connection to temperature or the shrinkage come into force.
From cold a piston with half a thou clearance will seize up if the car is driven too fast too soon (and remember this is the size of the cylinder next to the one that seized). as best as we can measure where it seized that cylinder had a couple of tenths of a thou clearance. The cylinders are shrinking but not much across the thrust face but in line with those main bearing shell thick support part of the block. This means that the tightest section is not now the usual place (across the thrust face of the piston main diameter) but either side of it and hence the piston has not seized in the centre and has seized at the sides.
However - if you can accept that evidence - I openly admit that the reason for the shrinkage can be debated and there may be many explanations - and I have offered 2 related to a common and well understood phenomenon that engineers are used to managing.
Anyway, it is only my advice to warm engines up thoroughly before thrashing them - I actually will get more business if you ignore that advice - good luck everyone.
Baz
I suppose people think I must be lying when I say we measured the bores that have seized (not scored) and the adjacent ones and found clearances shrunk down to less than half a thou in the areas either side of the centre thrust direction where the piston has seized (and that after over 70K and pistons also worn down a little) the next cylinder half that shrinkage and the last one no shrinkage.
They cannot have been made like that or the engines would not have lasted for over 70K.
It is entirely illogical not to understand that something has caused the clearances at the bottom of some cylinders to shrink inwards in the area immediately in line with the large section casting that also holds the main bearings.
It is also illogical when told that all 5 seized in winter and after a very short distance driving admittedly fast from cold - all sorts of other explanations that have no connection to temperature or the shrinkage come into force.
From cold a piston with half a thou clearance will seize up if the car is driven too fast too soon (and remember this is the size of the cylinder next to the one that seized). as best as we can measure where it seized that cylinder had a couple of tenths of a thou clearance. The cylinders are shrinking but not much across the thrust face but in line with those main bearing shell thick support part of the block. This means that the tightest section is not now the usual place (across the thrust face of the piston main diameter) but either side of it and hence the piston has not seized in the centre and has seized at the sides.
However - if you can accept that evidence - I openly admit that the reason for the shrinkage can be debated and there may be many explanations - and I have offered 2 related to a common and well understood phenomenon that engineers are used to managing.
Anyway, it is only my advice to warm engines up thoroughly before thrashing them - I actually will get more business if you ignore that advice - good luck everyone.
Baz
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Wayne Smith (11-22-2023)
02-14-2019, 10:23 AM
#440
Former Vendor
And now we go down the oil rabbit hole. Anyway, last year the API came up with a new rating category. SN plus, which is meant to protect against LSPI.
I spent the a couple minutes looking and there are no A40 and SN Plus oils. Every oil except the euro ones has been upgraded to the new standard.
I think the DI40 may be ahead of its time.
I spent the a couple minutes looking and there are no A40 and SN Plus oils. Every oil except the euro ones has been upgraded to the new standard.
I think the DI40 may be ahead of its time.
the moral of this story is that practical application trumps everything. From the engineering perspective it is often frowned upon today as a way to develop, but to some of us we realize that it is the ONLY way to truly develop.
Warm up is critical, but allowing the engine to warm up too long, without load keeps the cold start, and just started fuel enrichment higher than optimum, while the system is trying to light off the catalysts. Fuel is a great solvent, and a poor lubricant. Driving the car easy, without heavy load and massive throttle is a key, and avoiding static idle time while the engine is still under enrichment is another.
After the failure Bronz' engine I have decided to build a mule engine for my R&D dyno. We have a theory that needs to be proven the old fashioned way. The good thing about having the R&D dyno cell is an engine can stay there as long as it takes to work through an issue, since that cell isn't used for testing customer's engines. I think this one will be there for months.
02-14-2019, 01:45 PM
#441
bgeotz not sure if you were referring to me, but I think you may have gotten the wrong impression. I was merely trying to correct misinformation, so that some myth is not perpetuated. His statement was not true based on the data in this thread. He said, "Its simply coming into the stage of the life cycle that the 997.1 has already been through". I quoted Jake not to make myself feel better, but to state a data point from a reliable source that contradicts what the other member said. My other post actually goes into the failures (not trying to denying failures happen) and my agreement with Baz that a few blocks shrank for whatever reason and improper warmup with forged pistons could lead to damage if you have one of these rare blocks.
I tend to think that the hysteria over this engine failure is way overblown. This thread went from what could have just been a great learning experience of a rare instance to the sky is falling. I have owned many different makes of performance vehicles and there are failures in every make and model. The amount of worrying that goes on in this board is way beyond anything I have experienced on any other board.
I tend to think that the hysteria over this engine failure is way overblown. This thread went from what could have just been a great learning experience of a rare instance to the sky is falling. I have owned many different makes of performance vehicles and there are failures in every make and model. The amount of worrying that goes on in this board is way beyond anything I have experienced on any other board.
Last edited by edomund; 02-14-2019 at 01:46 PM. Reason: mispelled name
02-14-2019, 01:59 PM
#442
Instructor
Warm up is critical, but allowing the engine to warm up too long, without load keeps the cold start, and just started fuel enrichment higher than optimum, while the system is trying to light off the catalysts. Fuel is a great solvent, and a poor lubricant. Driving the car easy, without heavy load and massive throttle is a key, and avoiding static idle time while the engine is still under enrichment is another.
I suppose for those of us unable or unwilling, as the case may be, to get down in the weeds on this matter along side of the obviously well-informed among us (E.g., Jake Raby, etc.) this advice is the big takeaway. (Don't get me wrong, this discussion is fascinating, but my engineering acumen is limited..)
I suppose for those of us unable or unwilling, as the case may be, to get down in the weeds on this matter along side of the obviously well-informed among us (E.g., Jake Raby, etc.) this advice is the big takeaway. (Don't get me wrong, this discussion is fascinating, but my engineering acumen is limited..)
02-14-2019, 02:01 PM
#443
Instructor
Warm up is critical, but allowing the engine to warm up too long, without load keeps the cold start, and just started fuel enrichment higher than optimum, while the system is trying to light off the catalysts. Fuel is a great solvent, and a poor lubricant. Driving the car easy, without heavy load and massive throttle is a key, and avoiding static idle time while the engine is still under enrichment is another.
I suppose for those of us unable or unwilling, as the case may be, to get down in the weeds on this matter along side of the obviously well-informed among us (E.g., Jake Raby, etc.) this advice is the big takeaway. (Don't get me wrong, this discussion is fascinating, but my engineering acumen is limited..)
I suppose for those of us unable or unwilling, as the case may be, to get down in the weeds on this matter along side of the obviously well-informed among us (E.g., Jake Raby, etc.) this advice is the big takeaway. (Don't get me wrong, this discussion is fascinating, but my engineering acumen is limited..)
02-14-2019, 03:48 PM
#444
bgeotz not sure if you were referring to me, but I think you may have gotten the wrong impression. I was merely trying to correct misinformation, so that some myth is not perpetuated. His statement was not true based on the data in this thread. He said, "Its simply coming into the stage of the life cycle that the 997.1 has already been through". I quoted Jake not to make myself feel better, but to state a data point from a reliable source that contradicts what the other member said. My other post actually goes into the failures (not trying to denying failures happen) and my agreement with Baz that a few blocks shrank for whatever reason and improper warmup with forged pistons could lead to damage if you have one of these rare blocks.
I tend to think that the hysteria over this engine failure is way overblown. This thread went from what could have just been a great learning experience of a rare instance to the sky is falling. I have owned many different makes of performance vehicles and there are failures in every make and model. The amount of worrying that goes on in this board is way beyond anything I have experienced on any other board.
I tend to think that the hysteria over this engine failure is way overblown. This thread went from what could have just been a great learning experience of a rare instance to the sky is falling. I have owned many different makes of performance vehicles and there are failures in every make and model. The amount of worrying that goes on in this board is way beyond anything I have experienced on any other board.
02-14-2019, 04:44 PM
#445
I drive my 2008 C2S with a light throttle and below 3K rpm until the oil hits 200F. Then over the the next mile raise the rpm and add more throttle (e.g. 4K then 5K). I believe this is important to longevity. The owner's mauls for our 2016 Audi A6 and 2016 Golf S both indicate that how you break in your car and how you drive it when the engine is cold will have a significant impact on the condition of the engine when it ages. I also remember when I had a 1978 VW Rabbit Diesel. It was recommended that one cool down the engine at a high idle ( 1500 rpm?) for about two minutes after driving the car at highway speeds. This was evidently due to the fact that the engine had forged pistons that they hold more heat and may not cool down like the block does during shutdown. I don't know if it was true but I do this with my 997 as well. The last mile is also driven with a light throttle and moderate revs before I go through the shutdown process. I do not know if I have bore scoring but my car uses oil at the rate of about 1 qt/6K miles. The other cars use little to no oil. I change the Porsche oil once per year (every 3-3.5K miles) with Mobil 1 at the dealer. I had the plugs changed last year at 30K miles and the tech said they were in good shape.
What else can one do?
What else can one do?
02-14-2019, 08:29 PM
#446
So this seems to need a mult level approach to help prevent and seems to be across most manufacturers just saw this video interesting take on multi approach maybe jake can chime in
he has suggestions of add mass air cooler
change to one range cooler plugs
https://www.exxon.com/en/product-faqs
Volatility refers to a series of characteristics that measure a fuel’s tendency to vaporize at a given temperature. Since gasoline must vaporize before mixing and burning with air, formulating fuel with the correct volatility is critical for achieving good drivability.
High volatility gasoline vaporizes more readily than low volatility fuel and is frequently blended during the winter season to ensure easy cold startup and smooth warm up.
Something I didnt know
"hot weather, gasoline that is too volatile can cause vapor lock and other hot fuel handling problems"
Our additives are accurately injected as each delivery truck is filled at the terminal, ensuring the quality of our fuel and providing additional benefits
Really good read here
https://www.oronite.com/about/news/low-speed-pre-ignition.aspx#LSPI-prevention There are several factors that contribute to LSPI, of which lubricating oil has been observed to be one.Many factors have been demonstrated to impact low speed pre-ignition (LSPI), including: engine designs, fuel composition and lubricant composition
nice read about oil here from chevron
https://www.oronite.com/about/news/low-speed-pre-ignition.aspx#lubricant-and-LSPI
On the lubricant side, the most noticeable impact has been from the detergent chemistry. Oils with higher concentrations of calcium, which is found in many detergent systems, have been shown to increase the frequency of LSPI. The exact chemistry of the detergent is less important to LSPI than the calcium content. Conversely, magnesium-based detergents do not seem to promote LSPI. Although reducing calcium may seem like a solution to control LSPI, there may be other performance tradeoffs to consider.Molybdenum compounds, for example, not only provide frictional benefits, but also have been shown to decrease LSPI when used at high levels.
he has suggestions of add mass air cooler
change to one range cooler plugs
https://www.exxon.com/en/product-faqs
Volatility refers to a series of characteristics that measure a fuel’s tendency to vaporize at a given temperature. Since gasoline must vaporize before mixing and burning with air, formulating fuel with the correct volatility is critical for achieving good drivability.
High volatility gasoline vaporizes more readily than low volatility fuel and is frequently blended during the winter season to ensure easy cold startup and smooth warm up.
Something I didnt know
"hot weather, gasoline that is too volatile can cause vapor lock and other hot fuel handling problems"
Our additives are accurately injected as each delivery truck is filled at the terminal, ensuring the quality of our fuel and providing additional benefits
Really good read here
https://www.oronite.com/about/news/low-speed-pre-ignition.aspx#LSPI-prevention There are several factors that contribute to LSPI, of which lubricating oil has been observed to be one.Many factors have been demonstrated to impact low speed pre-ignition (LSPI), including: engine designs, fuel composition and lubricant composition
nice read about oil here from chevron
https://www.oronite.com/about/news/low-speed-pre-ignition.aspx#lubricant-and-LSPI
On the lubricant side, the most noticeable impact has been from the detergent chemistry. Oils with higher concentrations of calcium, which is found in many detergent systems, have been shown to increase the frequency of LSPI. The exact chemistry of the detergent is less important to LSPI than the calcium content. Conversely, magnesium-based detergents do not seem to promote LSPI. Although reducing calcium may seem like a solution to control LSPI, there may be other performance tradeoffs to consider.Molybdenum compounds, for example, not only provide frictional benefits, but also have been shown to decrease LSPI when used at high levels.
02-15-2019, 03:52 AM
#447
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9A1 is not turbocharged, so aircooler does not help. DFI systems on all cars have this problem (among others like carbon buildup in intake), high compression ratio and lean mixtures. These engines are tuned close to edge because they need to comply with emissions and need to make good power.
When you are already on the edge, only small problem in the fueling/ignition system can cause this failure. And there is no cylinder liner can save you for this, not nikasil, not even steel.
Those who are about to lose their sleep... Dont
Just drive the car and enjoy, odd's are low that your car will die. 
I have put 100k km's to my 996 at 8y and still going.
Oh, and remember, there is not one car maker nowadays, that has bullet proof engines on all of their cars.....
When you are already on the edge, only small problem in the fueling/ignition system can cause this failure. And there is no cylinder liner can save you for this, not nikasil, not even steel.
Those who are about to lose their sleep... Dont
Just drive the car and enjoy, odd's are low that your car will die. I have put 100k km's to my 996 at 8y and still going.Oh, and remember, there is not one car maker nowadays, that has bullet proof engines on all of their cars.....
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Wayne Smith (11-22-2023)
02-15-2019, 10:43 PM
#449
Three Wheelin'
I know some have taken a one off failure and it has scared many, but like it has been said already all mechanical things eventually break no matter how well you take care of them. I would just like to personally thank Jake, Charles & Baz for taking time out of their very busy schedules to chime in. They have more knowledge than 1000 of us combined and then some and they have shared that freely. Thanks guys. It is people like you that keep this world a good place to be from. Thanks.
02-16-2019, 12:48 AM
#450
Burning Brakes
I'd really like to know what this type of rebuild costs, but I can't find any reliable info for a 9A1 engine rebuild. If it's $10k - $15K that's an acceptable risk. But, $30k is not. My car plus $30k would get me a turbo.