M96 Engine design and failure

From May issue of the Excellence magazine: "When the Boxster and 996 were relatively new cars and the M96�s problems were not yet understood, rumors suggested that up to 50% of the cars were going to experience failure. Porsche addressed the problems and, today, I am hearing the number of cars that have had or will have a problem is closer to 20%, or one in five." Am I reading this right?? Does this even make sense? How many N/A 996 owners on Rennlist? 500? That means 100 will have had or will have an engine failure (presumably prematurely as all engine WILL fail one day)?

I only know 1 person personally that had the IMS failure. It happened under the new car warrenty and it was replaced. I did see another 99 C2 with a blown engine and a really beat up and abused 99 boxster with a blown engine. Then again I know many others with no problems and 3 of them drive 99's and 2 have over 100k km. There is even a person in Toronto with all most 500k km on his 996. I will hit 100 k km this year and other then burning a bit more oil, the engine runs fine. I think if you look back into the history of the 996 forum you would find it hard to find 10 blown engines and I am sure there are more then 500 rennlist memebers that have had a 996 on this forum. Should you be concerned, Porsche wasn't so I wouldn't.

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I like to think it means 400 996's won't have a problem and that the other 100 that will have problems are Boxster's.

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Is that 20% of all M96s sold - or 20% of the early years? Either way, it's a disgrace

If it makes you all feel better, my 2000 996 is still ticking away with over 110,000 miles but I blew my "most reliable 911 engine ever" (3.2L Carrera). Well, kinda, just bent the exhaust valves.

Nothing wrong with the engine's design... Many parts of the engine are exceptional, like the cylinder heads for one. The issue is the cost cutting that Porsche enabled with the engine's components.. We have worked to overcome the inadequacies of the engine and honestly all it takes is better component quality. We unlocked another reason that adds to the IMS failures on Saturday of last week, during another test session, and this one may be the most difficult to address, with the biggest expenditure of both time and money yet. Lots of IMS failures, aren't really a failure of the IMS.. Porsche dealerships often mis-diagnose the issues and not until the engine is opened up do they find out what really failed was the IMS drive chain tensioner paddle. Here is a post I made on 986 forum a few months ago that illustrates this failure and how it has ALL the classic examples of an IMS failure, but isn't. In fact, this IMS was in perfect condition other than the damage it received from schrapnel from other components when it scattered. http://986forum.com/forums/showthrea...7&page=2&pp=20 95% of Porsche dealerships don't have a single Employee on the staff that has done more to one of these internally than change a cam cover in the real world.. They receive training at school, but even then they don't assemble an engine by themselves. Until recently they were not authorized to do any internal repairs, even a lifter swap or a timing chain.. That has changed and now I get a call at least once every couple of weeks from a dealership tech somewhere in the country calling to ask US a question! I recently hired a factory trained tech that spent a few years at Brumos, and he had no experience with the engine's internals and states that everyone there was in the same situation! So, while the engine may not be the best on the planet, don't blame that on the design as much as the German Accounting that far superseded the German Engineering that went into the composition of the M96 engine family. Once updated with "overkill Engineering" components and assembled with Human hands (instead of a Robot) the engine is what a Porsche engine should be.

Thanks Jake... very informative!

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+1

I had 2 M96 engine replacements in the life of my 996. The original engines issue was the RMS seal bore was out of round, the replacement engine lasted 500 miles before it blew with an IMS failure. The 2nd replacement engine has been flawless. BTW, the third engine was installed in 4 hours (and that included the R&R of the clutch assembly).

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No wonder in/out/under your engine is so spiffy!

The original engine was just as clean!

Most of the RMS issues have been weeded out for several years, today this mode of failure is the least of our concerns; though we do have preventive measures to reduce it's occurrence in our engines. Most engines that were going to have an RMS or case porosity issue have already failed and been taken care of.

Jake, have you ever come across a reman engine that failed? If so, can you note any differences in construction, materials, if any? Thx for your input.

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Absolutely. Some examples are on my site, under the engine reliability featured article.

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I tried to download the pdf, but there is an error. http://www.flat6innovations.com/m96-engine-reliability

I'm a bit disappointed in Porsche. An engine can only be as strong as its weakest link so it doesn't matter how well all the other parts are designed/manufactured, all it takes is just one weak critical component to fail. I'm not worrying much and this is definitely not meant to be another dome's day thread. So back to my point. No matter how you count that 20%., how can it be anything remotely close to reality?? My hope is on the new 9A1 engine It looks promising. Of course only time will tell...

My 2002 had the RMS replaced twice and on the third replacement they decided to investigate it more thoroughly and discovered that there was a casting defect. In any case, I settled for the x51 replacement and now has 2k miles on it and hope that this engine is far more reliable. Time will tell.

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Jake, Have you seen similar IMS issues on the 997/987 cars or are these problems confined to the 996/987? I'm curious because it seems that we don't hear of these problems as much on the later cars. On the other hand, many of the replacement engines and the early 997/987 engines should have been manufactured at the same time (and presumably share the same updates). Thanks, Joe

IMS failures are common with ALL models.. They have not occurred with the 87/97 series as much yet, but these cars are much newer than the 86/96 engine family. In the beginning, IMS failures also were not as widespread with the earlier engines, the D chunk, RMS and case porosity issues were the primary modes of failure. Porsche attempted to address the issues through a series of changes, but unfortunately some crontributing factors to the failures were never addressed and the component quality and bearing application were also never addressed completely..

So a reman engine transplant that occurred in say in an MY 2002 3.6 engine and a reman engine in MY 2004 same engine... safe to say that the latter will have the newer parts than the former. what is making these reman engines less prone to failure? i'm really curious what porsche is doing with these as they assemble them... it seems like no one as any real insight. perhaps you can shed some light on this raby? i'm really glad to see you here, btw, as i'm sure others share in the sentiment.

I'm sure I'm asking a question that's been answered in a thread or two about IMS failure, but am hoping someone will be kind to a newbie. I just purchased a 2007 Boxster S with only 17.6K miles yesterday. Service records via CarFax were quite thorough. The car purrs like a kitten (or a larger cat at higher rpms) and has a 2-year Porsche certified warranty. I've read and been told that after a redesign of the flawed part that the IMS failure is much less likely (though still possible) on '07 and newer Boxsters, and it seems that most (all?) of the reports of failure I've read are on older models. How worried should I be? I assume that Porsche will cover me for any failure within two years, but I plan to keep the car for longer assuming it's solid. I suppose I could always spring for an overpriced extended Porsche warranty after the two years/50K miles elapses.

Use the search function there is a million threads on this!! I wouldn't even be concerned, Just do an IMS bearing replacement when your clutch is due for replacement if you want peace of mind!!

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Jake--How involved is changing the IMS drive chain tensioner paddle? How long should it take? I'm basically trying to figure out what this should cost me. Thanks.

Check out this Pelican Parts Boxster Tech Article: Camshaft Upgrade / Chain Tensioner Replacement http://www.pelicanparts.com/techarti..._Tensioner.htm

It appears to me that there have been very few reports of engine failure lately on the forums. Am I right here? I take this as a good sign.

Whenever I click on "Engine reliability" from the Flat 6 site I get the same thing... nothing...

Holy Thread Resurection Batman! 2007 M96 should be good... But if you are worried, change to the LN Engineering bearing if they have a version for your car.

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Its the 4th part thats assembled onto the crank carrier assembly.. It requires complete engine disassembly just to facilitate its removal and replacement.