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I’ve noticed recently that there are a slew of negative views on this forum on the demise of the M96/97 engines as a result of bore scoring. It seems to me a lot of 996/997 owners are under a lot of pressure lately trying to stay on top of the well-being of their cars and are paranoid after reading all the negative views and the mishaps of some that are having problems. Even Cayenne, which does not use the flat-6 are having these issues and over at that forum frustrated owners are spreading rampant fears like a doomsday coming. The widespread effect of internet negative views of the current problems is causing a lot of grief and anxiety among the owners. The reality is that other than a few that are encountering problems with their car, you would never ever hear of anyone coming forward to say how good their car has been.
I must admit as a 997.2 CS2 owner I was at first affected by these negative vibes caused by the bore scoring. And the general conclusion was that the 996/997s are now over 15 years old and are falling apart in the worst case scenario with engine failures. Upon reviewing and reading all the forum posts these cars all have fairly low mileage. I would say the majority of them are under 70K miles and I wonder how in the world could this be possible. My personal conclusion is that the failures are happening in a few isolated cases and it is the internet effect that is causing a doomsday scenario and given the impression that this problem is running rampant throughout a lot of Porsche owners.
It also seems to me the more people read on the reasons why the engine fails, the less they can identify the cause of it. The reason being nobody can identify the real cause of it. From cylinder bore and piston coatings, angle of the crank arm piston, the kind of fuel we use, the environment, the climate, the geographic location, the way we drive, the warm up cycle, the rpm range NOT to dwell on while cruising, the engine oil. . . etc, etc, etc, etc . . . the list goes on and on. Every possible cause of bore scoring are all covered and who ever encounters a mishap to their engine would inevitably fall into one of these category. My reaction was the same when I first encountered a problem. But then I thought it over . . . hey, I’m not “the old lady from Pasadena”, who is clueless about her/his car as someone who never ever pop open their engine bay. Prior to retirement I was a software contractor and quite often had to resolve/fix issues. I would be the point man to fix things and there weren’t any luxury of second-guessing myself, let alone coming up with multiple LIKELY causes. The problem with multiple likely causes is the exponential factor. By the time you throw in multiple likely causes and even after fixing it, you’ll never know what was causing it in the fist place. Under such scenarios we are just lucky to hit upon the right fix. So if the problem happens again, applying the same fix will likely not fix it at all. Surely given all likely reasons that bore-scoring could result will make mis-diagnose of the cause impossible, or equally impossible either to accurately diagnose the cause of it.
After reading the postings relating to this issue, one of the symptom of scored cylinder is a ticking and knocking sound that could be heard with the engine idling when first started. My car had the exact symptom and I was devastated. From that day I spend a lot of time trying to figure out what to do. Took it to an indy and the mechanic briefly examined it and confirmed the ticking/knocking noise was caused by either a scored cylinder or a worn crank bearing. Either case, it was bad news. I couldn’t sell the car and couldn’t drive it and the sinking feeling was perhaps close to having being diagnosed with terminal cancer. I finally took the initiative and decided to get to the bottom of the issue. I was pleasantly surprised of the outcome and lifted a heavy load off my chest.
Refer to this thread for those interested on what I found out. https://rennlist.com/forums/997-foru...ing-sound.html.
It just shows that what we don’t know and what we perceive could have a very negative experience. This is not to say the ticking/knocking sound were not caused by bore-scoring. But in my case, it came from another source. Perhaps I’m just fortunate in identifying that the ticking sound as normal and I want others to be aware that the ticks and knocks could very well be a non-issue as in my case.
The scored cylinder bore surely is having a profound impact on us. Case in point, I was interested in a Cayman R and was at a stage of selling my 997.2. Had a potential buyer and he was adamant in allowing the PPI inspection access to scope the cylinders. I was hesitant at first because the procedure is quite invasive. I don’t know about the other models, but on the 997.2 you have to put it on the lift, remove the wheels, then the mufflers, the shields, the coils and spark plugs to be able to view the innards of the cylinder. PPI on Porsches used to be quite direct and simple before the rampant scare of bore scoring and now everybody wants to have a visual inspection of the cylinder bore. The shop told the potential buyer that the bore inspection was an additional $200. The garage looked quite professional and capable so I agreed to allow them the visual bore inspection. Anyway, the report card for my car came back with flying colors. On a score of 1 — 10 (10 being a new car), it could have scored an easy 9. The entire process took a little over an hour and while the car was up in the air, they removed all the underbody covers and examined everything. No fluid leaks, not even minor weeps. The cylinder looks as new. Everything looks pristine. Anyway, a long story short. The buyer was clueless. Everything on my car was perfect, but it has a stage one over-rev and I was the culprit of it when the car was new to me. Unbeknown to me the previous owner installed the close spacing of the 3 pedals for toe and heel. The accelerator has an adjustable side plate, but I have wide feet and with my size D+ sneakers, stepping on the brakes will inadvertently brush on the throttle while disengaging the clutch. This was the cause of the one over-rev (stage one). Anyway, the potential buyer was clueless, showing all the classic example of someone who concludes that a little knowledge quite often is detrimental. After spending quite a bit for the PPI and gone through all the trouble, he backed out of the sale. The headache started right after while I was driving home. On the way back I noticed that there was a metallic clanking noise that weren't there before. Due to the rush hour at the time, I decided not to go back to the garage. The next day, I put it on jack stands and went beneath the car and found the culprit. After doing the cylinder scoping which required taking the side muffler off, it was not installed back correctly. The exhaust piping joining the muffler to the exhaust was crooked, thus hitting the heat shields. I was pissed. Anyway I corrected the problem and all was well until a day later there was another rattle underneath the car. Back on jack stands again and this time I found out several torx fasteners securing the underbody panels were missing, thus causing a rattle. The garage left some torx fasteners out when they put the covers back. Again I fixed it. Had the garage that did the PPI not being 30 miles away I would have gone back and give them a peace of my mind. It was right then I decided never ever sell my car to any clueless buyers. I would request to be at the service bay while they perform the invasive bore visual inspection and make sure they put everything back correctly. There are just too many inept mechanics doing their monkey wrenching out there and the well being of my bloody mental state of mind is more important. I reason that any competent mechanic should be able to access the condition of the car based on symptoms of bore scoring without having to dismantle everything just to get a visual.
Before my retirement in the last century I was living in Los Angeles and working in the Bay area. I used to fly out of Burbank to San Jose and then fly back for the weekend on a weekly basis. Although the flight itself was only 1 hour, but if you factor in the time required to travel to the airport, went thru security clearance, check-in, wait at the gate, fly out to San Jose and then retrieve my car and drove to the office, the time required were a good 3+ hours. Later on I decided to just drive from LA to San Jose, which took about 4 hours and quite frankly the drive was quite enjoyable, except going through the Grapevine during winter when it snowed in. The car I was using was a BMW E30 and back in the 1980s, when synthetic oil wasn’t as popular then, I was using conventional oil and I put in roughly 1.5K miles a week. So I was changing oil just about every month and wearing out a set of tires every year. After it accumulated 1/2 million miles and although it is still reliable and never ever left me stranded, I decided not to push my luck further. Nothing worse than being stranded in the middle of interstate 5 out in the boonies. By the time I donated the car and wrote it off as business expenses back in 1999, the BMW E30 had accumulated over 1/2 a million miles on the original engine. Sure I had brake jobs, suspension work, timing chain and valve adjustments done on it, but the engine just kept going and it DID NOT DRINK A DROP OF OIL, . . . ALL ON CONVENTIONAL MOTOR OIL. The reason I bring this up was one of the variables of scored cylinder could be related to engine oil. People starting to second guess whether the synthetic oil, although approved by Porsche, is detrimental to the well-being of their engine. I’m not a motor oil expert and would leave comments to those more qualified than me. Who knows why in my case with the BMW E30 using conventional motor oil would outperform even today’s modern synthetics. Are we now going backwards ?
Anyway, back to the topic of this posting. Comparing to other makes of cars, dropping the oil pan of a 911 is a fairly easy task. I think for the peace of mind it should be part of the maintenance every 50K miles. I also want to do this due to some forum members finding all kinds of broken parts and debris after dropping the oil pan. Having read their encounters I made a point to see what kind of junk resides in my car. The procedure for me was to put it on jack stands, drained the oil, unplugged the oil sensor and then loosen all the parameter torx bolts on the oil pan. There are 2 bolts holding it at the center of the oil pan. Loosen and remove one, there you are left with only one center bolt holding the oil pan. Finally loosen the last one. Due to the gasket holding the pan, I had to pry it loose. Use a plastic trim tool so you don’t mar the mating surface. The pan came loose. Be careful because there is still about 2/3 quart of oil left that cannot be drained out. Refer to the pictures and you will see why by design the drain hole cannot completely drain all the oil. Tilt the pan and dump the remaining oil into the used oil container. Remove the gasket (mine is still very pliable). Pay attention to 2 rubber plugs/spacers that seals the center 2 bolts. The new gasket does not come with the 2 center rubber seals and I had to reuse them. They might be stuck onto the top panel. Just pay attention not to lose it. Putting everything back is just the reverse. Just make sure the new gasket is fitted within the grooves of the mating surface. It will hold and no RTV is necessary. Make sure the 2 rubber plugs/spacers are within the center holes for the 2 bolts. Hand tight the torx bolt and using a diagonal cross pattern gradually tighten the bolt. The torque value is a mere 10Nm so exercise care not to over tighten it.
Now for the drama of what I found inside the oil pan :
NOTHING, NILCH, NADA, no sludge or any contaminants on any surface. The bottom of the oil pan was shiny and pristine. No debris, no grit, no metal specks/filings, nor any plastic pieces. Not even a film of residue settling on the bottom of the pan. I was expecting at least a bit of metal filings carried over from the factory because the oil strainer will only pickup the oil from the center of the baffling partition within the oil pan.
Examine these pictures. Note that the drain hole is collared so that the drain plug can be threaded onto the pan. The lip is about 2cm deep and that is why you will never be able to drain all the oil out. Just remember if you ever drop the pan for inspection to put in an additional 2/3 quart of oil on the refill afterwards. Note the internal baffling of the oil pan and the flaps that traps the oil within the center partition. Unless one is critically low on engine oil, the design should prevent any oil starvation. Look at the oil strainer, it is clean as a whistle. I was expecting perhaps at least a film of contaminants at the bottom, at least on the sides of the pan that the oil sits outside of the baffling partition, but it is as clean as the day it left the factory. I’m quite happy with the oil I am using. It seems to get darkened quickly, but I kind of like that. A lot of folks assume clean oils coming out of their engine in pristine condition is the hallmark of a good oil. In fact the opposite is true. I would worry more if the oil stays clean for a long period of time because the contaminants would not have been suspending within the oil and would have been settling within the engine somewhere, and most likely at the bottom of the oil pan. But the oil I use held the contaminants in suspension and proves the detergents are working as it supposed to. Changing oil twice a year I don’t even find a haze of contaminants on the bottom of the pan. I want to stay away and refrain from disclosing what engine oil I’m using because I’m not an oil man and have no finance reasons to vouch for any motor oil. It is like God and country, any debate would never ever be settled. I’ll leave the oil comments to the expert that knows more than me.
There is still about 2/3 qt of oil as seen here that cannot be drained out.
After dumping the rest of the oil, see how clean the bottom of the pan shows. No contaminants could be found anywhere.
Spiffy clean !!!
Cannot find anything on the oil strainer.
There are 2 center spacers with O-rings (not shown) to seal the 2 center bolts. Don't lose those O-rings
Slip the new gasket onto the groove. It will hold the gasket. No RTV sealant is needed. Gradually tighten the oil pan bolts with a criss-cross sequence and then torque to 10 Nm.
The built-in oil baffle at the bottom of the pan.
Drain plug threaded onto a collar in the oil pan. This is why you cannot completely drain the oil out.
The one-way flap allowing oil flowing into the baffle and contain it for the oil pickup.
In conclusion, we drive Porsches and want the best for our cars. Nothing is worse than not knowing the ins and outs and when encountering a problem left us vulnerable to all the rumor mills of the reason and cause of the problem. I’m not saying that we should ignore all the valid advice, as some offered by reputable engine builders are very educational. But we as Porsche owners should be able to judge for ourselves on the pros and cons of all opinions. This forum helped me a lot, but on the other hand with the knowledge gained, one should be able to act intelligently. The M96/97 engines have their issues. While I wouldn’t say that these engines are bullet-proof, but Porsches have been designing and building the flat-6 for eons and these cars are build and designed to be driven.
Personally I feel bad seeing those that are having problems with their cars (including the Cayenne owners). Of course their problems are legit and my guess is that out of tens of thousands owners out there, the odds of a few Porsche owners having scored bore problems are not rampant. To those encountering these problems, my hats off to them for coming out and addressing the issue. Also appreciate the engine rebuilders offering their insight on this issue. Posting any information on this subject requires some resilience because as in any papers or thesis, there will be comments and criticisms. That is just the nature of the business. I hope that firstly the engine rebuilders find the actual cause and give us proofs beyond any reasonable doubt as to the cause of these engine failures. Due to the odd case of this scenario happening perhaps we would never know the cause. We should not be too stricken on this in preventing us from enjoying driving our car. I think as long as you don’t abuse the car, there is no reason our car will meet its demise. Hopefully this thread will cheer up those that are going through the agony.
While I can’t confidently say my car wouldn’t encounter any problems down the road, but I can honestly say after addressing all the minor issues, the car now is better than the date when I first bought it.
HERE, I’M DECLARING MY CAR (997.2 CS2) TO BE PROBLEM FREE AND IN PRISTINE CONDITION (knock on wood). I have my sights on another Porsche, the Cayman R and hopefully it will pass my scrutiny. I’m in my seventies and will continue enjoy driving my Porsche into the sunset. At this point I’m pretty sure the car will outlast me. Let’s hear from some other happy owners.
Cheers !!!
Nice expertise?! Man, this is 9A1 DFI engine, not that M96/M97 you are mentioning. Because of ignorant people like you, Porsche got away with horrible M96/M97 engine. I would say 9A1 is just average design in practice, genuine maybe 200K mile engine, which considering price/complexity is nothing special, just AVERAGE.
M96/M97 engines will go in history books marked as some of the worst engines ever made. With so much catastrophic failures, it is genuine 60K mile engine if we count smaller IMS design. Even updated WILL fail sometime, but those are maybe 100K mile engine which for a 100k USD car is just pathetic. And yes, rest of 997 (not counting clutch) is brilliant!
Nice expertise?! Man, this is 9A1 DFI engine, not that M96/M97 you are mentioning. Because of ignorant people like you, Porsche got away with horrible M96/M97 engine. I would say 9A1 is just average design in practice, genuine maybe 200K mile engine, which considering price/complexity is nothing special, just AVERAGE.
M96/M97 engines will go in history books marked as some of the worst engines ever made. With so much catastrophic failures, it is genuine 60K mile engine if we count smaller IMS design. Even updated WILL fail sometime, but those are maybe 100K mile engine which for a 100k USD car is just pathetic. And yes, rest of 997 (not counting clutch) is brilliant!
Boy, re-read my post again before you blow hot air. I also mentioned Cayenne having score-bore issues which is not even a flat 6. Yes, mine 997.2 is problem free as I stated in my writeup. So what is your beef ?
Boy, re-read my post again before you blow hot air. I also mentioned Cayenne having score-bore issues which is not even a flat 6. Yes, mine 997.2 is problem free as I stated in my writeup. So what is your beef ?
It's uselles write up, with zero knowledge on this subject. Rose tinted glasses anyone?
Watering down this forum, where I learned so much about this cars
Ok Guys here is my 2 cents ... Can these engines score we all know the answer but so can the .2 . Overall these engines are decent and robust enough to provide a good ownership experience, I should know as I have both a 955 Cayenne S and a 997.1 4s and I have not experienced any issues with either.
Do I worry ? Sure once in awhile when I read such posts but being a product failure analyst in my prior occupation and a large part of what i did was tracking failure rates in thousands of mechanical products I know this issue in the big picture is minimal in scope ... Can it happen yes !! will it happen to me or anyone else highly unlikely.
I can tell you from experience that we are all using products every day which what we call in the industry as SIR (Service Incident Rate) that are considerably higher than the rate of failure on these engines. Normally an incident rate of less than 2% is considered excellent and normally reserved for electronic items only. Anything mechanical with an SIR of less than 8-10% is still considered quite acceptable and not a catastrophic issue.
The issue remains that when I experienced a product failing you only hear in a big way from the small percentage of owners who have had the failure and not from the other 90% and as crappy as this may sound, this is the reality of anything mass produced and even more significant when you are dealing with complex mechanical products.
I can get into multiple ways mfg's address such issues but in general these engines are fine and will last a long time ... Could they be better sure but overall I know of many that have not been babied like we baby ours and are treated like daily drivers with their owners knowing nothing about "bore scoring" approaching over 200k with no issues so don't worry about it and just do your regular maintenance and things should be fine for a long time.
Ok Guys here is my 2 cents ... Can these engines score we all know the answer but so can the .2 . Overall these engines are decent and robust enough to provide a good ownership experience, I should know as I have both a 955 Cayenne S and a 997.1 4s and I have not experienced any issues with either.
Do I worry ? Sure once in awhile when I read such posts but being a product failure analyst in my prior occupation and a large part of what i did was tracking failure rates in thousands of mechanical products I know this issue in the big picture is minimal in scope ... Can it happen yes !! will it happen to me or anyone else highly unlikely.
I can tell you from experience that we are all using products every day which what we call in the industry as SIR (Service Incident Rate) that are considerably higher than the rate of failure on these engines. Normally an incident rate of less than 2% is considered excellent and normally reserved for electronic items only. Anything mechanical with an SIR of less than 8-10% is still considered quite acceptable and not a catastrophic issue.
The issue remains that when I experienced a product failing you only hear in a big way from the small percentage of owners who have had the failure and not from the other 90% and as crappy as this may sound, this is the reality of anything mass produced and even more significant when you are dealing with complex mechanical products.
I can get into multiple ways mfg's address such issues but in general these engines are fine and will last a long time ... Could they be better sure but overall I know of many that have not been babied like we baby ours and are treated like daily drivers with their owners knowing nothing about "bore scoring" approaching over 200k with no issues so don't worry about it and just do your regular maintenance and things should be fine for a long time.
I have to agree, while initially shopping for a 996 and hearing all the horror stories, I realized that my budget allowed me to look at 997's. Then I realized that even 997's had theor horror stories.
So I took the time to look further into it and called the service manager at my local dealership. The guy said that he recommended the 997 way over the 996, and he'd been the service manager for 14 years and had never seen an IMS or bore scoring problem with any model they sell.
And that is up here in Ottawa Canada where we have winter conditions at least 4-5 months of the year. Of course most people store their 911s during winter time, but some drive them year round.
He then started lecturing me about the internet....
Just bought my 997 last week and while in Montreal, I asked the same thing to the service manager and got more or less the same answer, which also ended with that same internet lecture...🙄
This is a common trend... open a old engine to find that condition is great and could last many more miles. Meanwhile people are changing their oil every 2000 miles and paranoid.
Reality is modern engines are really reliable. Unless its a GM or Ford product...
Observation 1: the Internet amplifies anything by 100x.
Observation 2: Even dealers hire idiots to do work. My high end car was up for sale and the ppi was done at a dealer. The idiots measured the paint thickness right through the clear bra and concluded that the hood and bumper had been repainted because the paint was thicker there. Ruined the sale. That dealer will not get a cent, or a referral from me.
Observation 3: Buyers who are affected by the internet amplification are 90% of the buyers out there. You have to deal with it.
Observation 1: the Internet amplifies anything by 100x - Observation 3: Buyers who are affected by the internet amplification are 90% of the buyers out there. You have to deal with it.
BAT is a hotbed for this kind of activity. If an auction can survive all of the criticism in those comments then they probably deserve the hammer price. I think politics looks easier in comparison.
BAT is a hotbed for this kind of activity. If an auction can survive all of the criticism in those comments then they probably deserve the hammer price. I think politics looks easier in comparison.
Sad but true. I see people on this forum who do not own a 997, let alone a 911, opining on all of the things to look out for. Their knowledge is purely anectdotal and based on what they read online from anonymous sources. My Indy always tells me to stay off the internet and enjoy the car.
Yes, go figure. As an earlier post blowing hot air on this thread all because I shown my car being problem free. Either he is delusional or there is a self-interest agenda behind it.
04-07-2019, 02:39 AM
GUESS WHAT I FOUND INSIDE THE OIL PAN !!!!
