M96 IMSB Failure Rate Surpasses 8%

For those that are even keeping up with it: The IMSB failure rate has passed the 8% milestone, held steady, and is creeping closer to the 9% mark. Everyone who has not considered replacement should at least consider that the potential for failure is certainly there. Its just too cheap of a fix to ignore it and do nothing, IMHO of course.

Still, one of the most unscientific polls on the planet.

Nonono, the rate of those that REPORTED on this poll is exceeding 8%. The response rate has nothing to do with the actual user rate in the wild. Jake/LN say they have sold, what, close to 7000 bearings to date? (I think this is correct but please correct it if not). Presumably those engines were all good at the time and still are. So there are close to 7000 people out there that have not responded yet along with everyone else who either did something else bearing-wise, did nothing and have had no issues, along with a relatively small number that did have the big bang. Many of these three groups have never heard of Rennlist or don't bother with it. The poll is a biased sample and not valid from a statistical perspective relative to the number of cars in operation.

There is zero statistical reliability to that survey. There were well over 250k M96-equipped cars built by Porsche, 8% of less than 1% is meaningless.

Also, there were only 230 replies (19 failures). I would guess there are way more than 230 current 996 owners on Rennlist (anyone know the actual number? I would guess in 1,000s) who didn't bother to reply that their cars are great.

Marc, can we delete this thread? It's just baiting. (I bit). I know you did not want to do the poll to begin with, but it's there now, no point in having threads about it that don't take into account any kind of statistical theory whatsoever.

No one holds the failure data to calculate these statistics accurately. The private sector does not have Porsches figures and Porsche does not have the private sector figures. In my classes this question is my biggest pet peeve, I won't even attempt to address it. Intermix failures far surpassed the IMSB in terms of landing vehicles at our facility over the past 3 years. So many cars being retrofitted is definitely contributing to this as the figures far surpass 7,000 today.

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This.

Just say no.

Intermix failures ... Jake what % are 3.4l versus 3.6l. On the 3.6 is there anything you can do as preventative ?

Just for the record - I got mine done on my 1999 996 - for the record - it's over and done with for now. Best part is that - I got to visit the best porsche workshop - got to talk to my mechanic .( which I love doing) Got to see tons of Porsches getting worked on - which for me is better than ****. Um - and don't forget the fact that they are amazing machines - and if you wanted a stress free car - then you should have bought a new Toyota - Btw - this is going out to all the people that are about to start crapping on about IMS issues - for everyone else - I am sorry for crapping on about nothing :P

I just replied to an IMS post, but currently suffering from a "potential intermix" situation, so the % probability shed s a new light onto what I thought was a "manageable" situation. I wonder what the "stats" are for intermix. Tomorrow the car goes into the dealer for a complete coolant flush, pressure/vacuum test, and see what happens.

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I don't give a single damn about statistics.. All I know is we now have Porsches at our facility from 27 states, shipped 4 home last week and are scheduled to receive 3 more this week to take their place. The phone blows up all day and I had to add another line just so people didn't receive a busy signal. Other than a few preventive procedures everything that we deal with is dead on arrival. Intermix from cracked heads, cracked cylinders and the like has us buried.

Situation: owned the car since March 18, 2013. Have had 3 instances where white puff of smoke came out the mufflers, but could only confirm that two of those times the smoke came strictly from the passenger side muffler tip. No relationship as to how I drove the car previously to parking it or how many days it sat without being use, but the common thread denominator is that it was only on the initial startup of the day. Local stealer admitted to overfilling oil on the second day I owned the car. The puff of white smoke gets dramatically less in size each time, where the last one is about the size of a shoebox. In the last week, not one puff of smoke. Following a couple of pictures of what the coolant looks like. No oil residue on cap, nor on top of the reservoir. Water in expansion tank not thick at all. Local coolant used is pink in color (Porsche branded), but does not mean that the PO used a different shop to do a flush. Tomorrow, the car goes into the local stealer for a coolant flush and vacuum test to determine if in fact there is a leak somewhere. I too usually don't give a damn about statistics (easily manipulated unless all known factors are expressed), but when you are sitting on a $30K toy with a $20K potential problem, I do start giving a damn.

But it could be worse... You could have a 13-15K toy that requires a 20K engine. Thats the boat that about 5 of my clients are in right now, but all 5 of them are going to keep the car forever, so they are moving forward. It happens more than you'd ever imagine. That does look like very early intermix. Lets don't hijack his thread any more, though :-)

Jake: I have nothing more than the upmost respect for you. I understand and respect your point. To the OP, my most sincere apologies for the temporary hijack. Let's move on and not worry about the exceptions to the rule.

This thread could also have the title " Only 19 reported M96 IMSB failures " and be equally correct based on your data source...

IMHO-- The IMS bearing is a consumable item just like other wearable components and should be changed as such (i.e., clutch, brake pads, belts, tires, IMS bearing, etc.), but especially when changing the clutch since you are there already.

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Does Flat Six pay you for posts like this or does he have an account he credits?

All I can say is that I have 126,000 miles on my Boxster and 112,000 miles on my 996 - both with original IMSB's and still running strong. But maybe I'm only part of the 92% "lucky" owners.

It's funny how people are so ready to dismiss statistics. Yes it's a painful thing when this happens to you, but the reality now and always has been that IMS is a problem that affects a very small number of people, so pretending like your engine is poised to implode is an over reaction. This issue has singlehandedly and unnecessarily blemished the record of a very reliable car.

I'd like to see some statistics and numbers (stateside) regarding bore ovality and scoring, and head cracks. Hartech has a bunch of soft data from the other side of the pond, but I hear little of these issues here.

OMGZs what's worse is that the IMS failure rates in cars that flat6 sees are nearly 100%!!!!!!! I also hear that the cancer rates of people that see oncologists are nearing 100% as well, and almost all people that call plumbers have plumbing problems.

By popular demand I have closed this thread. Happy Driving all!