Video Part 8 "The 3.8L Scoring Duo" is out
12-24-2019, 11:20 AM
#166
Nordschleife Master
Join Date: Mar 2003
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If you refer to my reply on "997.2 bore scoring just when etc" on this page (or actually read our full report) you will see that - we managed to get std pistons re-coated by Mahle Motorsport with their latest coatings (which seem the same as Ferrotec and we believed to be Ferrotec) and tried them in Lokasil - but they soon showed signs of wear on the surface - unlike Ferrostan. They also had the same lack of magnetic pull and looked the same - but they were not good enough in our opinion to fix the problem long enough with Lokasil. Furthermore it would seem extremely odd if both Mahle (who provided the Ferroprint pistons) and Porsche decided not to use an alternative that would fix the problem that the supplier already had available - but decided to use something inferior that has caused all these long term problems and damage to their reputation? furthermore Alusil makes machining the blocks much more expensive than Lokasil (which was why it was introduced) - do you think if Ferrotec would work in Lokasil Porsche would have reverted to Alusil in the Gen 2 unnecessarily?
But as Jake alluded to - the cost of a repair is all in the labour stripping, cleaning, remanufacturing and rebuilding with new replaced parts that you would never use again during any rebuild. Furthermore crankshaft bearings, chains and tensioner blades wear etc etc. if you are going to incur the cost of a strip and rebuild it makes no sense whatsoever not to add the small extra cost of fixing other weaknesses with the best solutions available.
997.2 and Henry - you and others may be in denial for some time as it seems to be a knee jerk reaction to any post trying to finally bottom out causes. I am not really incentivised to respond in detail when I am sure that eventually it will become clear that my explanation is right. We have experienced all this before but eventually everyone usually forgets who got it right and who didn't and it just becomes an accepted diagnosis - meanwhile - as soon as a likely explanation surfaces there seems a rise in activity to prove it wrong. However there are a few points that might help divert your attention back to an explanations that fits all evidence.
For example - why would carbon from spark plugs affect bank 2 and not bank 1 until about twice the mileage? The top of a piston above the rings is machined with much more clearance than the body of the piston below the rings and is never intended to touch (or get close to) the bores (only ever might when the top of the bore has become so oval (or the bores and piston are so badly scored) that the piston rocks madly over TDC and the very edge of the top might touch). Scores rarely reach anywhere near the top as a result (see numerous photos) - usually all below the rings height. Any carbon flakes that might fall into the bore would be too big to slip under the three rings and then reach the part of the piston that transfers the forces of the power stroke by pushing on the cylinder bore to push the rod down and the crank round. A carbon flake or piece is not as dense as a silicon particle and would be blown out by the exhaust which is of course on the underside of the cylinder and be more likely to be blown out in this layout than an upright cylinder in which it would tend to sit on top of the piston for longer.
Our report identifies the size of the silicon particles and has the picture of the DLC coated pistons (that we tried along with many others) revealing the nature and size of the scoring marks in their early stage that finally brought our attention to what should have been obvious all along. Many serious technical reports on Alusil accepted but then sped past the fact that silicon particles were indeed eventually and gradually released from the bore material but none then thought about what happened to them (as if they just disappeared into thin air) or what damage they could then cause? I have not seen the consequence of those particles sitting between the piston and the cylinder bore considered before.
I have not worked out the forces on the piston face (too busy) but the force from the burning fuel pushes the piston down and the angle of the rod at Maximum side thrust is quite early on in the rotation cycle when if I did have time to resolve all those forces would be adjusted/resolved by the angle of the rod to the bores and finally work out a thrust loads on the area of the piston that pushes against the cylinder bore to create torque. Whatever that force is - the oil film is sufficient to keep the piston and bore surfaces apart during the cycle unless the piston grows too large or the oil gets too thin etc. Because of the complex shaping of a piston - that surface area is about half the area of one side face of the piston below the rings. By contrast a piece of silicon grit is probably a factor of 500,000 times smaller and if it got between the piston and the cylinder - whatever the load that the piston would squeeze it by (load/area) would be something like 500,000 times greater and so easily cut through any oil film present. However - if the grit was smaller than the oil film - it should wash out. If it was larger it would first push the piston over to the opposite side of the bore (where there is minimal thrust load) to create a bit more clearance and eventually wash out. Pistons are also both oval, barrel shaped and tapered so although they tilt and roll so the thrust loads are supported by a relatively large area the actual minim clearance the bores and pistons are matched to only occurs near the bottom of the piston and a small area front to back. Every other part of the piston thrust face has more clearance. These clearances do reduce under prolonged full power (as the piston expands with the increased heat generated) but how many of us in normal driving - are regularly travelling at 160 plus mph? most often power is much more restricted and piston temperatures much lower and clearances across most of the piston are large enough to allow particles to wash out.unless they happen to get trapped just where the clearances are least. If for some fault reason the heat was above designed tolerances and the piston was growing closer to or bigger than the bore clearance after that it would obviously mark the bore and/or the piston coating.
The earlier M96 engines (with Ferrostan coated pistons) very soon went oval in the thrust direction, increasing the clearances to allow more silicon particles to escape without causing damage. Eventually a large enough piece could impact and wear the coating until pieces stuck towards the end game but the bores by then usually had greater clearances by far than the grit size and so ironically the ovality resulted in cracking - helped them survive longer. Alusil retained the particles for much longer and the Ferrostan coating survived much longer (as does the Ferrotec) but the bores do not go oval as much or as quickly so the impact damage of released particles would be potentially greater unless the coating was harder.
In a typical catastrophe theory spiral, there comes a point where (as rightly explained above by others) the trapped particle knocks more out and a score results - but once it has there is a space (the score) for the stuck particle (or any more that are released) to run up and down without then causing any further damage, the loads return to be shared by the remaining piston surface area (which are adequate) and the engines runs normally again until the next release until there are too many scores to not be noticed and repairs are required. This is why engines can run well with scores and for a long time before the oil consumption gets too high or the piston shape is too worn out with scores.
I know it is difficult to take on board a new explanation when so many others have been reported for several years and there is a natural tendency to prefer to stick with those previously accepted ones (and find fault rather than take on board a new solution) but if instead you would try and spend some of that thinking time imagining how my explanation works - I think you will find it more convincing.
Those that have seen the pictures in our report of various stages of coating wear and loss (especially the patches missing and the bubbled surface) will surely understand that a piece of silicon grit would then stick on the surface and the results that would cause?
As always - if you are mainly interested in finding out the real (or most likely to date) cause - please look at those pictures and spend some time thinking about the possibility that my explanation could be right and not just discount it out of hand and panic to find some way of discrediting it first without thinking the implications out fully.
I am not good at posting pictures but I am happy if anyone with the report can copy the pictures of ALL the piston coatings and post them on here large enough and clear enough to demonstrate the differences together with the picture of the different coatings we tried, the DLC coating and especially the ones with peeled coatings and the bubbled ones. I don't think the impact will be as good as combining it with the relevant writing but apart from the words describing each picture, I would prefer anyone assisting to kindly not copy any text (apart from the titles of the pictures) because the report was written to collect together a lot of information about different influences in different areas and I am concerned that by cherry picking our text - in smaller sections - the emphasis or even the reasoning and selective reporting might distort things too much and lose their correct meaning. This is another one of the reasons we preferred to apply the controversial NDA.
Baz
cdk4219 - Sorry I couldn't understand your reply about iron expanding causing the problem - please explain again a different way or more clearly and I will try? (or were you just having a laugh?)
.
But as Jake alluded to - the cost of a repair is all in the labour stripping, cleaning, remanufacturing and rebuilding with new replaced parts that you would never use again during any rebuild. Furthermore crankshaft bearings, chains and tensioner blades wear etc etc. if you are going to incur the cost of a strip and rebuild it makes no sense whatsoever not to add the small extra cost of fixing other weaknesses with the best solutions available.
997.2 and Henry - you and others may be in denial for some time as it seems to be a knee jerk reaction to any post trying to finally bottom out causes. I am not really incentivised to respond in detail when I am sure that eventually it will become clear that my explanation is right. We have experienced all this before but eventually everyone usually forgets who got it right and who didn't and it just becomes an accepted diagnosis - meanwhile - as soon as a likely explanation surfaces there seems a rise in activity to prove it wrong. However there are a few points that might help divert your attention back to an explanations that fits all evidence.
For example - why would carbon from spark plugs affect bank 2 and not bank 1 until about twice the mileage? The top of a piston above the rings is machined with much more clearance than the body of the piston below the rings and is never intended to touch (or get close to) the bores (only ever might when the top of the bore has become so oval (or the bores and piston are so badly scored) that the piston rocks madly over TDC and the very edge of the top might touch). Scores rarely reach anywhere near the top as a result (see numerous photos) - usually all below the rings height. Any carbon flakes that might fall into the bore would be too big to slip under the three rings and then reach the part of the piston that transfers the forces of the power stroke by pushing on the cylinder bore to push the rod down and the crank round. A carbon flake or piece is not as dense as a silicon particle and would be blown out by the exhaust which is of course on the underside of the cylinder and be more likely to be blown out in this layout than an upright cylinder in which it would tend to sit on top of the piston for longer.
Our report identifies the size of the silicon particles and has the picture of the DLC coated pistons (that we tried along with many others) revealing the nature and size of the scoring marks in their early stage that finally brought our attention to what should have been obvious all along. Many serious technical reports on Alusil accepted but then sped past the fact that silicon particles were indeed eventually and gradually released from the bore material but none then thought about what happened to them (as if they just disappeared into thin air) or what damage they could then cause? I have not seen the consequence of those particles sitting between the piston and the cylinder bore considered before.
I have not worked out the forces on the piston face (too busy) but the force from the burning fuel pushes the piston down and the angle of the rod at Maximum side thrust is quite early on in the rotation cycle when if I did have time to resolve all those forces would be adjusted/resolved by the angle of the rod to the bores and finally work out a thrust loads on the area of the piston that pushes against the cylinder bore to create torque. Whatever that force is - the oil film is sufficient to keep the piston and bore surfaces apart during the cycle unless the piston grows too large or the oil gets too thin etc. Because of the complex shaping of a piston - that surface area is about half the area of one side face of the piston below the rings. By contrast a piece of silicon grit is probably a factor of 500,000 times smaller and if it got between the piston and the cylinder - whatever the load that the piston would squeeze it by (load/area) would be something like 500,000 times greater and so easily cut through any oil film present. However - if the grit was smaller than the oil film - it should wash out. If it was larger it would first push the piston over to the opposite side of the bore (where there is minimal thrust load) to create a bit more clearance and eventually wash out. Pistons are also both oval, barrel shaped and tapered so although they tilt and roll so the thrust loads are supported by a relatively large area the actual minim clearance the bores and pistons are matched to only occurs near the bottom of the piston and a small area front to back. Every other part of the piston thrust face has more clearance. These clearances do reduce under prolonged full power (as the piston expands with the increased heat generated) but how many of us in normal driving - are regularly travelling at 160 plus mph? most often power is much more restricted and piston temperatures much lower and clearances across most of the piston are large enough to allow particles to wash out.unless they happen to get trapped just where the clearances are least. If for some fault reason the heat was above designed tolerances and the piston was growing closer to or bigger than the bore clearance after that it would obviously mark the bore and/or the piston coating.
The earlier M96 engines (with Ferrostan coated pistons) very soon went oval in the thrust direction, increasing the clearances to allow more silicon particles to escape without causing damage. Eventually a large enough piece could impact and wear the coating until pieces stuck towards the end game but the bores by then usually had greater clearances by far than the grit size and so ironically the ovality resulted in cracking - helped them survive longer. Alusil retained the particles for much longer and the Ferrostan coating survived much longer (as does the Ferrotec) but the bores do not go oval as much or as quickly so the impact damage of released particles would be potentially greater unless the coating was harder.
In a typical catastrophe theory spiral, there comes a point where (as rightly explained above by others) the trapped particle knocks more out and a score results - but once it has there is a space (the score) for the stuck particle (or any more that are released) to run up and down without then causing any further damage, the loads return to be shared by the remaining piston surface area (which are adequate) and the engines runs normally again until the next release until there are too many scores to not be noticed and repairs are required. This is why engines can run well with scores and for a long time before the oil consumption gets too high or the piston shape is too worn out with scores.
I know it is difficult to take on board a new explanation when so many others have been reported for several years and there is a natural tendency to prefer to stick with those previously accepted ones (and find fault rather than take on board a new solution) but if instead you would try and spend some of that thinking time imagining how my explanation works - I think you will find it more convincing.
Those that have seen the pictures in our report of various stages of coating wear and loss (especially the patches missing and the bubbled surface) will surely understand that a piece of silicon grit would then stick on the surface and the results that would cause?
As always - if you are mainly interested in finding out the real (or most likely to date) cause - please look at those pictures and spend some time thinking about the possibility that my explanation could be right and not just discount it out of hand and panic to find some way of discrediting it first without thinking the implications out fully.
I am not good at posting pictures but I am happy if anyone with the report can copy the pictures of ALL the piston coatings and post them on here large enough and clear enough to demonstrate the differences together with the picture of the different coatings we tried, the DLC coating and especially the ones with peeled coatings and the bubbled ones. I don't think the impact will be as good as combining it with the relevant writing but apart from the words describing each picture, I would prefer anyone assisting to kindly not copy any text (apart from the titles of the pictures) because the report was written to collect together a lot of information about different influences in different areas and I am concerned that by cherry picking our text - in smaller sections - the emphasis or even the reasoning and selective reporting might distort things too much and lose their correct meaning. This is another one of the reasons we preferred to apply the controversial NDA.
Baz
cdk4219 - Sorry I couldn't understand your reply about iron expanding causing the problem - please explain again a different way or more clearly and I will try? (or were you just having a laugh?)
.
Did you not say something a while back about piston angle in M96/97 that was perhaps addressed in the 9A1 or am I just missing that in these discussions?
12-24-2019, 11:23 AM
#167
I don't mean to derail this thread, but bear with me for a minute. It seems that most of this thread has been about the theories that surround the causes of bore scoring. Yes, I said theories. I'm sorry Baz, but in scientific research we avoid absolutes. Don't burn me to the stake, I didn't write the rules.
Anyway, is it wise to say that in order reduce the onset of cylinder bore scoring, that better oils and service intervals are a top priority? I know the other suggestions from Jake Raby about driving and caring for the car, but I haven't heard specifically what oils are better for those that DON'T have scoring. I would imagine that an oil with high ZDDP and moly are what I've seen suggested here on Rennlist and other forums. Are there any oil additives that need to be used or any "cleaners" from time-to-time? I know people will start preaching about the A40 recommendations and the little sticker on the deck lid, but would love to know what other owners think on the subject. Again, not encouraging an oil debate.
Thank you all. And, Merry Christmas and Happy New Year.
Anyway, is it wise to say that in order reduce the onset of cylinder bore scoring, that better oils and service intervals are a top priority? I know the other suggestions from Jake Raby about driving and caring for the car, but I haven't heard specifically what oils are better for those that DON'T have scoring. I would imagine that an oil with high ZDDP and moly are what I've seen suggested here on Rennlist and other forums. Are there any oil additives that need to be used or any "cleaners" from time-to-time? I know people will start preaching about the A40 recommendations and the little sticker on the deck lid, but would love to know what other owners think on the subject. Again, not encouraging an oil debate.
Thank you all. And, Merry Christmas and Happy New Year.
12-24-2019, 02:05 PM
#169
Three Wheelin'
Furthermore it would seem extremely odd if both Mahle (who provided the Ferroprint pistons) and Porsche decided not to use an alternative that would fix the problem that the supplier already had available - but decided to use something inferior that has caused all these long term problems and damage to their reputation? furthermore Alusil makes machining the blocks much more expensive than Lokasil (which was why it was introduced) - do you think if Ferrotec would work in Lokasil Porsche would have reverted to Alusil in the Gen 2 unnecessarily?
.
.
That being said, it's clear that you have tremendous expertise in this area and your explanation certainly makes sense to me. I also think that your theory regarding the scoring mechanism is right on the money and it fits all the available evidence (scoring pattern, material changes, year it started, going away in the 9A1, etc.). I did send in the NDA yesterday and look forward to reading the report.
Unfortunately this brings a sad understanding that there is an inherent flaw in the 997.1 engine that ultimately leads to bore scoring. It's not just an unlucky roll of the dice. The risk increases with wear and unlike the IMS bearing, it can't be preemptively fixed for less than $20k. It's a tough pill to swallow as it means 997.1 owners are on borrowed time, and there's nothing that can be done except some common sense steps that may (or may not, who knows) prolong the inevitable. Uggghhh. Not saying it will happen to every car but it's still a depressing thought and it seems to be where this is heading. On a positive note there's a great thread in the 996 forum of a guy who rebuilt his own bore-scored engine for something like $12k in parts and machining. LNE retrofitted his case with Nickies and provided great support of the rebuild so it certainly can be done by those motivated to do so.
I can see why Jake is so adamant that anyone considering buying a 997.1 must have an invasive bore-scope as part of the PPI. There will be a huge temptation for unethical folks to "unload" problematic cars at the first signs of scoring before it's completely obvious to some unwitting purchaser.
Last edited by PV997; 12-25-2019 at 09:48 AM.
12-24-2019, 02:50 PM
#170
Former Vendor
I can see why Jake is so adamant that anyone considering buying a 997.1 must have an invasive bore-scope as part of the PPI. There will be a huge temptation for unethical folks to "unload" problematic cars at the first signs of scoring before it's completely obvious to some unwitting purchaser.
The only negative of us sharing the info about early detection of the bore scoring issue, is it has empowered the sleaze ball sellers to have the engine checked as soon as it shows the first symptom, then they go sell the car to Car Max (we call this a "Max Attack") and unload the car before anyone knows that the issue exists. They don't usually sell it to a private party directly, because they feel like they'd rather take advantage of the big company. They don't realize that in most cases Car Max isn't going to sell these cars directly, they run them through an auction where smaller dealers end up with them, and then pass them on to a buyer, having no idea the scoring is occurring. The small dealer is actually not the bad guy, but if anyone upstream gets screwed, its going to be him.
Then the buyer gets his dream car, and ends up with a nightmare. He finds out about bore scoring the hard way, and we are his first message sent. I then reply with a canned reply about 2,000 characters in length, directing them to our videos, and etc, and they return a much better educated owner who says "I wish I would have known about this earlier". I tell them to look for signs that the oil sump plate has been removed, or that the coil packs have been recently removed. Ironically, In a lot of cases since I released my part 4 of the bore scoring series, showing the process I developed for scoping through the sump, lots of cars that belong to new owners that have gotten screwed have fresh sealant on the sump plate. We didn't see that before the video was released, as no one knew how to perform this test.
At that point it is too late. They love the car, and they are screwed, and broke. They have a car they owe a ton of money on, that needs an engine repair that starts at 20K.
This is a vicious cycle that I have seen play out over 50 times in 2019 in the exact same way.
Any 996 or 997.1 that is being purchased MUST HAVE an invasive bore scope inspection of both sides of the cylinder bore, on all 6 cylinders. Start with cylinder 6, and you might "down" the engine without looking at any other cylinder. If you don't find the issue on #6, then go to cylinders 4 and 5, and then over to bank 1, till you prove that no scoring exists. Again, this isn't done only to engines that show symptoms, you must perform this test if you are buying a car, no matter what. Does this cost money? Hell yes. Is this better than ending up with a rear engined paperweight? Hell yes. If a seller will not allow you to perform this test, then walk away from that car, and spread the VIN to this forum, and the FB groups out there, to warn others.
An educated seller of a clean, non afflicted 997.1 will have the bore scoring test carried out before the car is sold. This is a lot like Aircooled owners who have leak down and compression tests done when they decide to sell their car, to prove there are no broken head studs/ etc.
Also, forget a static leak down and compression test for bore scoring. It is absolutely, positively unable to identify problem cylinders. In fact, when we gather this datas from engines that we know have scoring, the afflicted cylinders test BETTER than the "good" cylinders. This fools the best out there, that don't have direct, and extensive M9X engine experiences. It defies conventional wisdom, but the reason why it happens is simple: Cylinders contaminated with oil will have the oil help provide a barrier to hold better compression, and less leakage than otherwise healthy cylinders. I plan to show this exact phenomenon in an upcoming Rennvision video of an engine that has confirmed scoring on several cylinders, some worse than others, and some not scored at all. A "running" compression test WILL show these conditions, if you are sly enough to watch the behavior of the needle on the gauge, and not pay attention to the value that needle is pointing too. This is all next level knowledge that we have gained directly, having seen our fist case of bore scoring 18 years ago. You won't learn it in a book, or by "researching" (Googling!) crap all day long.
I have been working on another, simpler test to identify engines that have scoring, but I do not trust that it will detect the condition at the earliest onset, yet. You don't even have to open the engine bay to do this test, and I have confirmed that we can identify bore scoring that is at stage 3 or beyond with great accuracy thus far. I just need more early onset cases to gather data, to confirm just how early the test has accuracy.
We will continue to learn, and share. Since we know that we can't stop bore scoring, all of my focus is on early identification of it, and resolving it for those who love their car enough.
12-25-2019, 07:28 AM
#171
A Xmas message on bore scoring.
Don’t worry about it – it is unlikely to impact during your ownership and if it does you can usually still drive the cars for 10 or 20 K (from very first signs) while deciding what to do about it and the prices reflect the uncertainty and there are some good proven solutions available, including capacity upgrades. Drive them spiritedly and enjoy – they are great cars.
More specifically - Doug H – if you are referring to the piston pin offset – the M96 up to 996 3.4 had an asymmetric piston crown shape so the pistons both sides had to have the same part pointing upwards (even though the thrust faces were on the top on bank 2 and bottom on bank 1) so this made one side offset fit the theoretical best offset and the other be wrong.
The Cayman S, 3.6 and 3.8 engines had symmetrical piston crowns so the pin offset could be orientated correctly in both banks – but it made no practical difference in anything we have detected. The 9A1 Gen 2 reverted to asymmetrical piston crowns so we concluded that Porsche found the same. We tested different offsets and found no differences and applied our results to our own special unique pistons for std and oversized engines.
Nutty – While many of us are trying to help owners be better informed to make their own decisions there are always some who don’t offer anything positive but try and muddy the waters and discredit providers by claiming nothing is proven and elevating their own position by claiming to represent science by stating the rather obvious that everything is theory – without ever doing anything to improve the quality of the current theories. They are all hypocrites because they still fill live their lives following convention but will not give credit to anyone trying to improve them. Yes the World could be flat and we may all not really be here but are living in a dream. Would they try hitting their thumb with a hammer because even though I claim it will hurt – I cannot prove it – it is only the latest theory – no - they use their intellect to reason with their life’s experiences and logic interpreting specialists advice plus convention to make decisions and decide it is not worth trying and everyone else is probably right – and conclude it definitely will hurt!. It’s an easy put down to use that argument – try technical points instead – I have provided enough for you to go at!
Cdk4219 - I think you mean that clearances change when driving? Bores always get bigger when the temperature rises but so do the pistons. However pistons are only measured for clearance in one spot where they actually distort under load and get smaller as well. Most of the piston (especially the top which is a round solid disc) are much smaller and have much more clearance. This is the problem designing a piston that is small and tapered enough not to expand beyond the clearance available at 170 mph yet not be too slack as most people poodle along under 50mph in traffic most of the time – and this is why the closer tolerances that are maintained with alloy cylinders and pistons are better than mixing them with iron blocks or liner.
PV997 – thanks for your supportive words – sorry I think you will have to wait till we are back at work in 2020 before Sharon can send your copy. Home builds are possible (we supply 1 new cylinder in a block for £600 ($775?) and all 6 for £2500 ($3230), but there are special tools needed and there are a lot of other options that specialists have available plus their experience and I would suggest that even experienced home mechanics would benefit from someone else putting at least the block together - or better still the whole engine. A lot of the cost is in the rest of the job which many could do themselves. Well worth exploring all options and which for UK customers Grant on auto@hartech.org will be happy to help. The whole job from car in to out can easily reach £8K ($10,500) plus most take the opportunity to replace other worn items like clutches at the same time so totals can go higher – but still great value wherever you are for the resulting quality of the rebuilt car. Some (like us) also provide valuable warranties - but beware some are not worth the paper they are written on! Reputation can help distinguish between the two.
Jake – early detection by a simple process would be a great benefit to help prevent owners buying a lemon – well done. Glad we both agree that eventually most engines will suffer and do such a good job rebuilding them. Practically we expect all piston coatings will be either worn, flaked or less well bonded by now and some small insignificant scratches will be in some bores. It is largely a question of time but that can surely be extended by some minor changes – but it will not go away and really we think drive it till it needs doing and enjoy it while you can.
Also agree any buyer must check what they are buying – chances to reduce the price and use the difference to contribute to a better rebuild if and when the time comes?
Hoping you all enjoy these wonderful cars in 2020 and beyond.
Baz
Don’t worry about it – it is unlikely to impact during your ownership and if it does you can usually still drive the cars for 10 or 20 K (from very first signs) while deciding what to do about it and the prices reflect the uncertainty and there are some good proven solutions available, including capacity upgrades. Drive them spiritedly and enjoy – they are great cars.
More specifically - Doug H – if you are referring to the piston pin offset – the M96 up to 996 3.4 had an asymmetric piston crown shape so the pistons both sides had to have the same part pointing upwards (even though the thrust faces were on the top on bank 2 and bottom on bank 1) so this made one side offset fit the theoretical best offset and the other be wrong.
The Cayman S, 3.6 and 3.8 engines had symmetrical piston crowns so the pin offset could be orientated correctly in both banks – but it made no practical difference in anything we have detected. The 9A1 Gen 2 reverted to asymmetrical piston crowns so we concluded that Porsche found the same. We tested different offsets and found no differences and applied our results to our own special unique pistons for std and oversized engines.
Nutty – While many of us are trying to help owners be better informed to make their own decisions there are always some who don’t offer anything positive but try and muddy the waters and discredit providers by claiming nothing is proven and elevating their own position by claiming to represent science by stating the rather obvious that everything is theory – without ever doing anything to improve the quality of the current theories. They are all hypocrites because they still fill live their lives following convention but will not give credit to anyone trying to improve them. Yes the World could be flat and we may all not really be here but are living in a dream. Would they try hitting their thumb with a hammer because even though I claim it will hurt – I cannot prove it – it is only the latest theory – no - they use their intellect to reason with their life’s experiences and logic interpreting specialists advice plus convention to make decisions and decide it is not worth trying and everyone else is probably right – and conclude it definitely will hurt!. It’s an easy put down to use that argument – try technical points instead – I have provided enough for you to go at!
Cdk4219 - I think you mean that clearances change when driving? Bores always get bigger when the temperature rises but so do the pistons. However pistons are only measured for clearance in one spot where they actually distort under load and get smaller as well. Most of the piston (especially the top which is a round solid disc) are much smaller and have much more clearance. This is the problem designing a piston that is small and tapered enough not to expand beyond the clearance available at 170 mph yet not be too slack as most people poodle along under 50mph in traffic most of the time – and this is why the closer tolerances that are maintained with alloy cylinders and pistons are better than mixing them with iron blocks or liner.
PV997 – thanks for your supportive words – sorry I think you will have to wait till we are back at work in 2020 before Sharon can send your copy. Home builds are possible (we supply 1 new cylinder in a block for £600 ($775?) and all 6 for £2500 ($3230), but there are special tools needed and there are a lot of other options that specialists have available plus their experience and I would suggest that even experienced home mechanics would benefit from someone else putting at least the block together - or better still the whole engine. A lot of the cost is in the rest of the job which many could do themselves. Well worth exploring all options and which for UK customers Grant on auto@hartech.org will be happy to help. The whole job from car in to out can easily reach £8K ($10,500) plus most take the opportunity to replace other worn items like clutches at the same time so totals can go higher – but still great value wherever you are for the resulting quality of the rebuilt car. Some (like us) also provide valuable warranties - but beware some are not worth the paper they are written on! Reputation can help distinguish between the two.
Jake – early detection by a simple process would be a great benefit to help prevent owners buying a lemon – well done. Glad we both agree that eventually most engines will suffer and do such a good job rebuilding them. Practically we expect all piston coatings will be either worn, flaked or less well bonded by now and some small insignificant scratches will be in some bores. It is largely a question of time but that can surely be extended by some minor changes – but it will not go away and really we think drive it till it needs doing and enjoy it while you can.
Also agree any buyer must check what they are buying – chances to reduce the price and use the difference to contribute to a better rebuild if and when the time comes?
Hoping you all enjoy these wonderful cars in 2020 and beyond.
Baz
12-25-2019, 07:58 AM
#172
In all fairness this isn’t much different, sure you could prevent failure, but the solution was to replace the IMS. The same could be said for bore scoring, your solution is to “replace” the cylinder lining.
Even if you are using a bit of “fear” in your marketing approach I don’t hold that against you at all. In fact quite the opposite, I think it is great business. Your success brings financial success to those who work for you and others you do business with. Additionally, you are obviously very good at what you do and care very much about the service you provide, providing a very high quality product. Business is full of these marketing approaches, many times for products that don’t meet consumer expectations. To many it is good business that results in higher share prices.
Overall, I think what you are doing is a really good thing. What does bother me somewhat is those who loose perspective on the fact that this is a luxury item that can be fixed. These people let the potential for an issue ruin their enjoyment of ownership, essentially ruining the car far before a mechanical issue has a chance. To compare not worrying about bore scoring to whistling past the grave yard as I read earlier is a total loss of perspective. One it puts a material thing in the same realm as your health and two I for one enjoy my life and some of the wonderful things it has to offer without dwelling on the ultimate end point and would hope most others do as well.
With such a far reaching message you of all people have the ability to curve this perspective, helping some of these types of people find more enjoyment around ownership and grow the enthusiasm for these cars. I will say that one of your last posts was very much in this direction was very refreshing and hope you help provide more of this type of message while continuing to provide good information and a great service.
On a business note, if you are booked over a year out and if you suspect the market will only continue to grow, I personally would look into how you can meet that demand. The increased volume could help leverage efficiencies and lower costs, further helping you grow your business. I know you will disagree, as I have read your response to similar suggestions, but it would certainly be an opportunity to make your services obtainable to a wider market of owners and help create more good jobs.
Then again there is the uniqueness and “prestige” brought by the fact that not everyone can afford/wait for a FS build as well as your ability to really control quality, so I suppose there is a balance. But man 1.5yr backlog seems like a missed opportunity to me. Just my $.02
Even if you are using a bit of “fear” in your marketing approach I don’t hold that against you at all. In fact quite the opposite, I think it is great business. Your success brings financial success to those who work for you and others you do business with. Additionally, you are obviously very good at what you do and care very much about the service you provide, providing a very high quality product. Business is full of these marketing approaches, many times for products that don’t meet consumer expectations. To many it is good business that results in higher share prices.
Overall, I think what you are doing is a really good thing. What does bother me somewhat is those who loose perspective on the fact that this is a luxury item that can be fixed. These people let the potential for an issue ruin their enjoyment of ownership, essentially ruining the car far before a mechanical issue has a chance. To compare not worrying about bore scoring to whistling past the grave yard as I read earlier is a total loss of perspective. One it puts a material thing in the same realm as your health and two I for one enjoy my life and some of the wonderful things it has to offer without dwelling on the ultimate end point and would hope most others do as well.
With such a far reaching message you of all people have the ability to curve this perspective, helping some of these types of people find more enjoyment around ownership and grow the enthusiasm for these cars. I will say that one of your last posts was very much in this direction was very refreshing and hope you help provide more of this type of message while continuing to provide good information and a great service.
On a business note, if you are booked over a year out and if you suspect the market will only continue to grow, I personally would look into how you can meet that demand. The increased volume could help leverage efficiencies and lower costs, further helping you grow your business. I know you will disagree, as I have read your response to similar suggestions, but it would certainly be an opportunity to make your services obtainable to a wider market of owners and help create more good jobs.
Then again there is the uniqueness and “prestige” brought by the fact that not everyone can afford/wait for a FS build as well as your ability to really control quality, so I suppose there is a balance. But man 1.5yr backlog seems like a missed opportunity to me. Just my $.02
If this was an isolated incident, it wouldn’t be an issue. There isn’t a company specializing in Chevrolet LS bore scoring fixes simply because It isn’t a problem. This is, however an extremely costly problem in these engines.
I personally don’t have the patience to rebuild an engine that has so many inherent flaws from the inception. ( Again if there wasn’t a problem m, it wouldn’t be an issue)
As far as I am concerned, Flat 6 is the doctor letting you know that it would be a good idea to get a colonoscopy, but you feel fine, and he won’t scare you into that because lots of people don’t have that.
If this scares you please don’t look and it won’t happen to you!
12-25-2019, 11:14 AM
#173
Nordschleife Master
Join Date: Mar 2003
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Make sure to tell your doctor that you don’t need any preventative screening or tests. Let him or her know that you consider this a fear tactic and you will be enjoying your life.
If this was an isolated incident, it wouldn’t be an issue. There isn’t a company specializing in Chevrolet LS bore scoring fixes simply because It isn’t a problem. This is, however an extremely costly problem in these engines.
I personally don’t have the patience to rebuild an engine that has so many inherent flaws from the inception. ( Again if there wasn’t a problem m, it wouldn’t be an issue)
As far as I am concerned, Flat 6 is the doctor letting you know that it would be a good idea to get a colonoscopy, but you feel fine, and he won’t scare you into that because lots of people don’t have that.
If this scares you please don’t look and it won’t happen to you!
If this was an isolated incident, it wouldn’t be an issue. There isn’t a company specializing in Chevrolet LS bore scoring fixes simply because It isn’t a problem. This is, however an extremely costly problem in these engines.
I personally don’t have the patience to rebuild an engine that has so many inherent flaws from the inception. ( Again if there wasn’t a problem m, it wouldn’t be an issue)
As far as I am concerned, Flat 6 is the doctor letting you know that it would be a good idea to get a colonoscopy, but you feel fine, and he won’t scare you into that because lots of people don’t have that.
If this scares you please don’t look and it won’t happen to you!
I am talking to a buddy right now in Miami that owns the premier, high end muscle car shop (restores, converts to modern suspensions and the only guy my friend down there trusts with his Veyron) about getting set up to drop something like that into 911s. He has done them before.
Seems like someone could make mint on coming up with an engine solution in the $10k range for the 997.1s or even the 996s because frankly, it’s not worth spending the value of a 12 to 20 year-old car (that will certainly continue to depreciate) to drop much more for an engine in it when you can sell the roller and apply the $25k plus toward another, newer car.
The stuff above pretty much makes it sound not quite a “not if, but when” . . ., but very close to it so values of M96/97 cars will certainly be impacted going forward.
RE: Leakdown on air cooleds
Yes, all of us long term Porsche owners have been doing that religiously on the air cooled engine for 30 years. Top end rebuilds are pretty much not an if, but when (which was around 60k miles), but I used to get those thone for about $4k or so. This is nothing like having to spend the value of your car or perhaps more for a repair/new engine. This is more of a long-term maintenance issuer.
12-25-2019, 11:16 AM
#174
Great questions. I've mentioned before I'm an engineer at a major commercial aircraft manufacturer that's been in the news lately, so I have some insight into how big companies react to high-profile engineering foul-ups. The first impulse is to "belt and suspenders" everything. It's costly, but when a company reputation is on the line it's a safe and reasonable approach to stop the bleeding. Later investigation (once things are under control) may show it's not needed and result in rollbacks. Perhaps this is an unfair comparison, but Porsche also designed out the IMS despite the fact there was nothing wrong with having an intermediate shaft (and a lot of good in having one). I suspect they judged that the public was not savvy enough to differentiate between the shaft itself and the bearing, so they just got rid of the whole thing. Belt and suspenders.
That being said, it's clear that you have tremendous expertise in this area and your explanation certainly makes sense to me. I also think that your theory regarding the scoring mechanism is right on the money and it fits all the available evidence (scoring pattern, material changes, year it started, going away in the 9A1, etc.). I did send in the NDA yesterday and look forward to reading the report.
Unfortunately this brings a sad understanding that there is an inherent flaw in the 997.1 engine that ultimately leads to bore scoring. It's not just an unlucky roll of the dice. The risk increases with wear and unlike the IMS bearing, it can't be preemptively fixed for less than $20k. It's a tough pill to swallow as it means 997.1 owners are on borrowed time, and there's nothing that can be done except some common sense steps that may (or may not, who knows) prolong the inevitable. Uggghhh. Not saying it will happen to every car but it's still a depressing thought and it seems to be where this is heading. On a positive note there's a great thread in the 996 forum of a guy who rebuilt his own bore-scored engine for something like $12k in parts and machining. LNE retrofitted his case with Nickies and provided great support of the rebuild so it certainly can be done by those motivated to do so.
I can see why Jake is so adamant that anyone considering buying a 997.1 must have an invasive bore-scope as part of the PPI. There will be a huge temptation for unethical folks to "unload" problematic cars at the first signs of scoring before it's completely obvious to some unwitting purchaser.
That being said, it's clear that you have tremendous expertise in this area and your explanation certainly makes sense to me. I also think that your theory regarding the scoring mechanism is right on the money and it fits all the available evidence (scoring pattern, material changes, year it started, going away in the 9A1, etc.). I did send in the NDA yesterday and look forward to reading the report.
Unfortunately this brings a sad understanding that there is an inherent flaw in the 997.1 engine that ultimately leads to bore scoring. It's not just an unlucky roll of the dice. The risk increases with wear and unlike the IMS bearing, it can't be preemptively fixed for less than $20k. It's a tough pill to swallow as it means 997.1 owners are on borrowed time, and there's nothing that can be done except some common sense steps that may (or may not, who knows) prolong the inevitable. Uggghhh. Not saying it will happen to every car but it's still a depressing thought and it seems to be where this is heading. On a positive note there's a great thread in the 996 forum of a guy who rebuilt his own bore-scored engine for something like $12k in parts and machining. LNE retrofitted his case with Nickies and provided great support of the rebuild so it certainly can be done by those motivated to do so.
I can see why Jake is so adamant that anyone considering buying a 997.1 must have an invasive bore-scope as part of the PPI. There will be a huge temptation for unethical folks to "unload" problematic cars at the first signs of scoring before it's completely obvious to some unwitting purchaser.
We are not learning much from these threads other than some cars are having this problem and that they can be fixed, expensively.
12-25-2019, 11:41 AM
#175
RE: LS
I am talking to a buddy right now in Miami that owns the premier, high end muscle car shop (restores, converts to modern suspensions and the only guy my friend down there trusts with his Veyron) about getting set up to drop something like that into 911s. He has done them before.
Seems like someone could make mint on coming up with an engine solution in the $10k range for the 997.1s or even the 996s because frankly, it’s not worth spending the value of a 12 to 20 year-old car (that will certainly continue to depreciate) to drop much more for an engine in it when you can sell the roller and apply the $25k plus toward another, newer car.
The stuff above pretty much makes it sound not quite a “not if, but when” . . ., but very close to it so values of M96/97 cars will certainly be impacted going forward.
I am talking to a buddy right now in Miami that owns the premier, high end muscle car shop (restores, converts to modern suspensions and the only guy my friend down there trusts with his Veyron) about getting set up to drop something like that into 911s. He has done them before.
Seems like someone could make mint on coming up with an engine solution in the $10k range for the 997.1s or even the 996s because frankly, it’s not worth spending the value of a 12 to 20 year-old car (that will certainly continue to depreciate) to drop much more for an engine in it when you can sell the roller and apply the $25k plus toward another, newer car.
The stuff above pretty much makes it sound not quite a “not if, but when” . . ., but very close to it so values of M96/97 cars will certainly be impacted going forward.
Some would scoff at the idea of putting an LN into a Porsche, but if you need a new engine, and you’re on a budget, it’s not the worst idea. You can also core swap your old engine and probably end up in decent shape on the project.
12-25-2019, 12:36 PM
#176
Pro
Let's see.... An inherent flaw in the engine that ultimately leads to bore scoring, it's not an unlucky roll of the dice, the risk increases with wear so 997.1 owners are on borrowed time but it will not happen to every car. Huh? Why do so many of these cars reach high mileage with no problems? How were the problem cars broken in, driven and maintained vs problem free cars? This would actually be helpful.
We are not learning much from these threads other than some cars are having this problem and that they can be fixed, expensively.
We are not learning much from these threads other than some cars are having this problem and that they can be fixed, expensively.
Use a thick oil with regular changes and run it till it scores or cracks, then scrap the motor or implement one of the replacements. Don't yet know if additives such as Zinc, Phosphorus, and Moly slow down the scoring, or if heavier weights help such as Porsche now uses with 5w-50.
12-25-2019, 12:41 PM
#177
Rennlist Member
As I understand the main difference between low and high-mileage bore score was determined during the casting process of an individual engine block. The distribution of silicon particles in the cylinder wall and stresses locked into the block as it cools that release over time and change the shape of the cylinder.
Use a thick oil with regular changes and run it till it scores or cracks, then scrap the motor or implement one of the replacements. Don't yet know if additives such as Zinc, Phosphorus, and Moly slow down the scoring, or if heavier weights help such as Porsche now uses with 5w-50.
Use a thick oil with regular changes and run it till it scores or cracks, then scrap the motor or implement one of the replacements. Don't yet know if additives such as Zinc, Phosphorus, and Moly slow down the scoring, or if heavier weights help such as Porsche now uses with 5w-50.
12-25-2019, 12:47 PM
#178
Pro
There is a gentleman in Maryland who can do a full LN conversion for around $11k. He specializes in 997’s, and has done 997.1 and 997.2 that have blown their motors.
Some would scoff at the idea of putting an LN into a Porsche, but if you need a new engine, and you’re on a budget, it’s not the worst idea. You can also core swap your old engine and probably end up in decent shape on the project.
Some would scoff at the idea of putting an LN into a Porsche, but if you need a new engine, and you’re on a budget, it’s not the worst idea. You can also core swap your old engine and probably end up in decent shape on the project.
12-25-2019, 12:47 PM
#179
Three Wheelin'
" it’s not worth spending the value of a 12 to 20 year-old car (that will certainly continue to depreciate) to drop much more for an engine in it when you can sell the roller and apply the $25k plus toward another, newer car."
For me, a few ways to think about this:
1) I have had my 2005 C2 since new. It has 37k miles on it , burns no oil, no soot or noises, runs great etc. I am dailying it about 75% of the time now and if I maintain it and drive and enjoy it to 100k miles (about 5yrs from now) without major BS issues, I will have a 20 year old car that does not owe me anything at that point . I can do a beast of a rebuild at that point, freshen every thing else up and it should be worth something considering the pool of manual, somewhat analog 997's will be limited to 997.2s and remedied 997.1s . As a result these could be considered "rare" at some point-no?
2) While it is asymptomatic, trade it in at a Porsche dealer for a newer model, at least I'd be throwing it back in their hands. Probably take a big hit on what they'd give me for it, but would have to work the price on the newer model.
3) While it is asymptomatic, sell it to someone who gets a clean PPI and knows the score on this issue and is happy
What else can you do at this point?
For me, a few ways to think about this:
1) I have had my 2005 C2 since new. It has 37k miles on it , burns no oil, no soot or noises, runs great etc. I am dailying it about 75% of the time now and if I maintain it and drive and enjoy it to 100k miles (about 5yrs from now) without major BS issues, I will have a 20 year old car that does not owe me anything at that point . I can do a beast of a rebuild at that point, freshen every thing else up and it should be worth something considering the pool of manual, somewhat analog 997's will be limited to 997.2s and remedied 997.1s . As a result these could be considered "rare" at some point-no?
2) While it is asymptomatic, trade it in at a Porsche dealer for a newer model, at least I'd be throwing it back in their hands. Probably take a big hit on what they'd give me for it, but would have to work the price on the newer model.
3) While it is asymptomatic, sell it to someone who gets a clean PPI and knows the score on this issue and is happy
What else can you do at this point?
12-25-2019, 12:52 PM
#180
Pro
As I understand 5w-50 is what Porsche dealers are filling M96/7s with. If correct that would be strong evidence that's the best weight to increase engine longevity.