This IMS Dark Horse...
#16
Quote from your very first post on Rennlist in 2013 before you acquired your 997.2:
QUOTE:
Thanx for you help. I am new to this forum as I owned a 2000 S Boxster for 12 years and 197K miles!!! For just some background my 2nd engine failed and that was it for this car. The first engine failed at 47K miles and was covered under warranty .... the 1st failure cause was unknown, the 2nd cause was also unknown but it definitely was NOT the IMS.
Check out my dearly departed 2000 S Boxster at around 175K miles.. note the painted wheels and roof.
My dearly departed car.
Thanx so much
Bruce in Philly
END QUOTE
Last edited by gripshifter; 02-15-2014 at 08:48 PM.
#18
Not impossible but improbable. All bearing manufacturers use Six Sigma statistical quality control. Such manufacturing defects are quite rare. That's not to say that incorrect fill for this particular application has been calculated to begin with, however, that will result into a whole production run (if not more) of "problem" parts and things like these usually trigger a recall.
Last the bearing does not have an infinite life. Nothing does. It is just a question of what fails first. If it wasn't the bearing it would say a chain and then everyone would be ranting about the lousy chains and offering up sorts of reasons when the chain failed prematurely. (My favorite explanation would be the chain is only as strong as its weakest link…)
Good design practice has a total system failure mode analysis performed and then tested both in house (durability test benches) and in vehicle, on the field. Known weak spots found on time are usually re-designed but at some point there's a revision freeze in which no other changes will be made in order to be able to ramp up production and launch the product on time. Anything that's not taken care of at the design stage will be assessed for risk of failure then added to the in warranty maintenance cycle of the vehicle or addressed on product "refresh". The problem part in question however has to be made as accessible as possible in order to keep warranty costs down...
People always complain... that's a given but for a product like Porsche, would be nice to know what to prepare for. I bet people would complain less in this case :-)
Last edited by BogdanR; 02-15-2014 at 11:28 PM.
#19
My point of saying I had two engines blow, was not to pile on the IMS issue or hide something to make a point (I am not sure what point I was really making as I am just frustrated). I am a frequent poster for 14 years now with the same moniker and all frequent readers should know about my engines. My point, albeit a veiled weak one, was expressing frustration at Porsche for making a substandard engine design. I think the IMS is just the most talked about and maybe the most common failure although it appears to get blamed incorrectly sometimes as was my 2nd engine.
All Boxster/Caymen/911 engines are variants of the same fundamental design (except turbo and GT3 as I understand) and suffer from multiple failure modes. And as many old timers have pointed out over and over for the 14 years I have been posting, many of us never remember having engines blow like this, American or German. It is beyond the flattening of the world via the internet, as I know personally folks who had their Porsche engines blow. Back in circa 2003 (?) at Jim Ellis Porsche in Atlanta, I could not believe my eyes when I was in the repair bay and asked the mechanic how common this was.... he just waived his hand and there were literally engines all over the place.... probably 7 or 8.
Unfortunately, wining like I am does not do anything for me or the good folks driving these cars today who hate reading this stuff. But I like many find it fascinating to read about all of the theory, speculation, and some good hard facts about the IMS issue.... my personal conclusion is that it just is a bad design all around from decisions made by accountants trying to save their company.
When Mr BogdanR made his/her original post, I both read it with fascination and a bit of "here we go again". It has been say 12 years I have been reading about this stuff. He clearly posts from a perspective of legitimate authority. But I think what triggered my post was a bit of "why are we analyzing one bearing when there are other modes that destroy this engine". At some point, I look at the whole engine as a system and just conclude the system is weak.
Anyway, my intent was not to challenge Mr/Ms BogdanR, but voice my frustration and fascination in watching engineering meet accounting meet saving a company meet serving a customer meet emotions meet the internet and all of us experts. Interesting...
Peace
Bruce in Philly
All Boxster/Caymen/911 engines are variants of the same fundamental design (except turbo and GT3 as I understand) and suffer from multiple failure modes. And as many old timers have pointed out over and over for the 14 years I have been posting, many of us never remember having engines blow like this, American or German. It is beyond the flattening of the world via the internet, as I know personally folks who had their Porsche engines blow. Back in circa 2003 (?) at Jim Ellis Porsche in Atlanta, I could not believe my eyes when I was in the repair bay and asked the mechanic how common this was.... he just waived his hand and there were literally engines all over the place.... probably 7 or 8.
Unfortunately, wining like I am does not do anything for me or the good folks driving these cars today who hate reading this stuff. But I like many find it fascinating to read about all of the theory, speculation, and some good hard facts about the IMS issue.... my personal conclusion is that it just is a bad design all around from decisions made by accountants trying to save their company.
When Mr BogdanR made his/her original post, I both read it with fascination and a bit of "here we go again". It has been say 12 years I have been reading about this stuff. He clearly posts from a perspective of legitimate authority. But I think what triggered my post was a bit of "why are we analyzing one bearing when there are other modes that destroy this engine". At some point, I look at the whole engine as a system and just conclude the system is weak.
Anyway, my intent was not to challenge Mr/Ms BogdanR, but voice my frustration and fascination in watching engineering meet accounting meet saving a company meet serving a customer meet emotions meet the internet and all of us experts. Interesting...
Peace
Bruce in Philly
#20
#21
Ok, since you are in the field....... Why couldn't Porsche find an answer? They kept blowing engines year after year.... Back in the day, every failure was crated up with an oil sample and shipped back to Germany... they saw and inspected the carnage.
In my non-engineering head, I get it that someone goofed or whatever.... then you fix it. Done. But what is it about this that they could not get correct? It just baffles me.
Any insight? Is this more of an engineering process or culture failure? Are the accountants are to blame?
Peace
Bruce in Philly
In my non-engineering head, I get it that someone goofed or whatever.... then you fix it. Done. But what is it about this that they could not get correct? It just baffles me.
Any insight? Is this more of an engineering process or culture failure? Are the accountants are to blame?
Peace
Bruce in Philly
Along the way it is a number's game. How many exactly have failed compared with the total number of vehicles already sold? Specifically how many warranty affected vehicles are we talking here? These are the questions Porsche had to answer and weigh in their response to the situation. If the problem number is relatively small, replacing engines under warranty while trying to fix an inherent issue with different bearing iterations will be less costly than a recall which will not totally solve the problem anyway. There's a whole inventory of parts waiting to be assembled into engines that have a rather low probability of developing a major problem, the engineering team works on ways of decreasing this probability further and the engine design boys have a new, direct injection powerplant in the works which makes this IMS history.
What would you do in this case? Probably exactly what PAG did... The incidence of problems was not high enough to trigger neither a recall nor a premature end of that engine program.
I'm sorry this issue has affected you so directly. I sure hope I will not be this unlucky...
Cheers!
#22
Last the bearing does not have an infinite life. Nothing does. It is just a question of what fails first. If it wasn't the bearing it would say a chain and then everyone would be ranting about the lousy chains and offering up sorts of reasons when the chain failed prematurely. (My favorite explanation would be the chain is only as strong as its weakest link…)
All parts are not equal. Some parts break, we replace them, and keep on driving. Some other parts break and ......KABOOOM!..... in other words, not all parts are equal.
Take steering linkages/parts. If they were to randomly break, say 5 percent of cars.... that could be quite a few deaths. So, car companies make sure these are designed to a higher specification. Internal engine kaboom parts, while not carrying a death sentence with them, are pretty darn important for serving your customer, maintaining a healthy used market, and preserving your brand reputation. I would think a smart company would work hard to ensure kaboom parts are wee bit tougher than say a coolant tank.
But hey, what do I know. We live in the world of this internet thing and most consumer companies would shoot themselves if they got this kind of bad press for 14 years.... but Porsche just raises its prices and sets sales records..... so who really are the smart guys and gals in this arena?
Peace
Bruce in Philly
#23
#24
You might try talking with Rabby's tech people; they are the after market bearing manufacturers and they have an idea how long these bearings will last and a recommended service life for one of the ones they produce. I think I remember 50k miles. They do the installs and charge 6k for the 997.1. They are very friendly over the phone. I've talked to them a couple of times.
#25
You might try talking with Rabby's tech people; they are the after market bearing manufacturers and they have an idea how long these bearings will last and a recommended service life for one of the ones they produce. I think I remember 50k miles. They do the installs and charge 6k for the 997.1. They are very friendly over the phone. I've talked to them a couple of times.
#26
My "educated" guess is they did find an answer but probably not THE answer we're looking for or we expected.
Along the way it is a number's game. How many exactly have failed compared with the total number of vehicles already sold? Specifically how many warranty affected vehicles are we talking here? These are the questions Porsche had to answer and weigh in their response to the situation. If the problem number is relatively small, replacing engines under warranty while trying to fix an inherent issue with different bearing iterations will be less costly than a recall which will not totally solve the problem anyway. There's a whole inventory of parts waiting to be assembled into engines that have a rather low probability of developing a major problem, the engineering team works on ways of decreasing this probability further and the engine design boys have a new, direct injection powerplant in the works which makes this IMS history.
What would you do in this case? Probably exactly what PAG did... The incidence of problems was not high enough to trigger neither a recall nor a premature end of that engine program.
I'm sorry this issue has affected you so directly. I sure hope I will not be this unlucky...
Cheers!
Along the way it is a number's game. How many exactly have failed compared with the total number of vehicles already sold? Specifically how many warranty affected vehicles are we talking here? These are the questions Porsche had to answer and weigh in their response to the situation. If the problem number is relatively small, replacing engines under warranty while trying to fix an inherent issue with different bearing iterations will be less costly than a recall which will not totally solve the problem anyway. There's a whole inventory of parts waiting to be assembled into engines that have a rather low probability of developing a major problem, the engineering team works on ways of decreasing this probability further and the engine design boys have a new, direct injection powerplant in the works which makes this IMS history.
What would you do in this case? Probably exactly what PAG did... The incidence of problems was not high enough to trigger neither a recall nor a premature end of that engine program.
I'm sorry this issue has affected you so directly. I sure hope I will not be this unlucky...
Cheers!
Porsche's use of larger bearings is a calculated compromise... larger bearings = longer MTBF = fewer in warranty claims. In fact, we've seen very few if any well documented large IMBS failures of the 997.1 (MY06-MY08) to date. Of course, for the few that may fail years from now it will be a costly expensive for the customer to service out of warranty as it will require a full engine tear down to replace the large bearings or worst the entire engine. Such an approach is, of course, likely calculated to minimize the cost to Porsche. Hmmm... my SWAG re MTBF for the larger bearings is a bit north of the 100K miles CPO max warranty coverage so if these blow at all it will likely be around 120K-140K miles perhaps. Odds are most of us will never experience this issue within our ownership time, however, there are many other more immediate and frequent issues to be concerned with such as the water pump, over heating, the Porsche recommend oil change interval(18K miles is way too long), scored cylinder walls, etc.
FWIW, some of us have taken a more preemptive/preventative and more frequent approach towards maintaining our 997.1. For example, I've added additional cooling capacity via a 3rd radiator and an FVD oil pan with increased oil capacity and cooling fins. Use of newly formulated Porsche approved oils, Motul Xcess 8100, vs. MB-1. More frequent oil changes every 3k miles/6 months along with getting an oil analysis from Blackstone. Replacing the WP before it fails... estimated between 40K-50K miles. Properly warm up the engine to operating temp before driving it hard. Shifting at higher RPMs, between 4K-5K as lower RPM shifts induces more load on the engine. Here's some night time reading from an M96/M97 engine rebuild shop out of the UK. May provide you with some additional insight.
http://www.hartech.org/docs/buyers%2...20part%205.pdf
FWIW, my engine has 63K+ miles on it and my oil analysis reports have been clean to date. Frankly the car has been much more reliable and more affordable to maintain than my prior BMW's. Just keep it well maintained and enjoy the ride. Nothing is truly failure proof... even the GT3's and TT's have their own issues. https://rennlist.com/forums/997-gt2-...-registry.html
Last edited by USMC_DS1; 02-16-2014 at 12:20 PM.
#28
Since this post goes over old ground here's a repeat of my 2 cents: switch to a grade 5 full synth oil, double up on factory recommended oil changes, and keep the revs up and the runs long enuff to keep oil hot and clean. Optional but cool: search the literature on Militec-1.
What is good for the engine overall is good for the bearing. Happy driving
Gerry
#29
I know this has been discussed to death, but it is apparent no one with timing drive design experience had chipped in with any knowledge. I see here statements that smaller bearings spinning faster are going to last longer than larger bearings spinning slower. This is an engineering fallacy.
Unfortunately grease life seems to affect sealed/ shielded bearings, which are greased for life, to a much greater extent than simple cyclic load induced fatigue. It’s a simple fact pre-packaged bearings have finite grease life and while this could be quite long actually, it is still finite.
Lack of adequate dynamic damping in the system also plays a big role in the life of the system. Damping is there to absorb vibration generated energy, especially at critical engine rpms. Without a suitable tensioning system capable of absorbing this energy, the rest of the system components will have to take the brunt of it, shorten the life of pretty much every component in the chain, IMS bearing included.
Again, welcome to the forum. Looking forward to your input.
#30
Welcome to Rennlist Bogdan. Hope you're able to capture that 997 next week.
Always good to hear from an actual expert in the field. Thanks for chiming in. I think you may be a bit fuzzy on this one. The large bearing and the smaller bearing are both spinning at the same rpm. The new larger bearing has larger diameter races. At the same rpm as the smaller bearing, this larger diameter inner race is traveling at a higher speed than the smaller race. Agreed , or am I missing something here?
Always good to hear from an actual expert in the field. Thanks for chiming in. I think you may be a bit fuzzy on this one. The large bearing and the smaller bearing are both spinning at the same rpm. The new larger bearing has larger diameter races. At the same rpm as the smaller bearing, this larger diameter inner race is traveling at a higher speed than the smaller race. Agreed , or am I missing something here?
Little history on M/96, M/97 cam chains. The early m96 engines had a five chain layout that saw a lot of wear on the chain guides. In I believe '03 that design was revamped into a three chain layout that has been fairly trouble free. Porsche stepped up and did the right thing here.
Thanks! And thanks for keeping me on my toes :-)