996 vs. 997 M96

While thinking about Keith's concern in the engine replacement thread, something occured to me. A quick Google query shows that the 997 uses an evolution of the same M96 block. If Porsche didn't fix the grenading motors completely with the 3.6, doesn't that mean one of two things? a) The engine has a design or manufacturing defect that Porsche has not found, and thus 997 engines can potentially blow up, too. or b) The engine has a design or manufacturing defect that Porsche has found and corrected, but refuses to take responsibility for on the 996? Justin

Justin - interesting thought! Of the two choices given, I would "guess" that B is the case. I spend almost as much time on the 997 Forum as I do here on the 996 Forum and I have heard of very few 997 engines grenading. Maybe Porsche did correct the manufacturing defect in the latesr version of the M96 block.

I'd say the answer is probably A. Although they may have "modified" the design, the 997 motors still appear to have the same RMS issues. It seems like Porsche feels it's less expensive to "repair" the RMS than to rework the architecture of the engine.

RMS isn't and has never been the reason of an engine failure. do a search. The 997, GT3s, 996 and Boxster/Cayman all continue to have leaks from the rear main seal which is corrected by putting in a new seal.

As a new 996 owner('02 C4 cab), I am just now being made aware of what I bought. I assumed at this stage of 911 evolution, Porsche would have refined and sorted out these cars. Can I assume that RMS is the Rear Main Seal, and that these 996 motors are prone to leak, fail or blow up? In reading thru many of these threads, it is also apparent that the best thing to do is to drive these cars in the manner in which they were intended to be driven- somewhat agressive and pushing the RPM's up to reasonable levels. Do I own a 'ticking time bomb'? I also have a pair of Audi D2 S8's, and they have tranny issues that I'm well aware of and prepared to deal with. Should I worry about my C4, or just continue to love it and drive it like I stole it? Thanks, guys. Jim

Keep in mind RMS is isn't what I was referring to. It just seems like either Porsche was/is screwing 996 owners, or they're about to go through it again with 997 owners. One of two things pretty much has to be the case, doesn't it? Jim, Drive it like you stole it. Refer to the "Engine replacement" thread. Personally, I think the odds are heavily in your favor that you will be in very good shape and nothing will ever happen. There is a small chance something will happen, but that's true of any car, and shouldn't deter you from the wonderful one you already have!

RMS failure was common, but will not cause engine failure. Porsche used to replace engines which suffered chronic RMS failures, but it was not because the engine itself failed. The current version of the RMS seems to work much better than the previous versions. RMS is just not a big deal. While early engines had some problems, the IMS failure is the thing that kills an engine regardless of year. It is unnerving, but no one is able to assess its frequency, and as is typical, Porsche won't say. My assessment is that it can't be that bad because you can buy an extended warranty, and those companies should know. My factory warranty ends early next year. I think I will buy a four year powertrain warranty for peace of mind as my solution. I should not have to, but the alternative is to sell the car.

Thanks, guys. I will drive it and hope for the best. I decided against an aftermarket warranty, because I figured the 911 was going to be rock solid and live up to its reputation for reliability. Now I am reconsidering. Any thoughts? Any suggestions on a warranty provider? I tend to be very risk tolerant by nature.

If you're so risk tolerant, then why are you even considering a warranty in all honesty? Go through your local Porsche dealer since they're going to likely be the ones you want to request a new engine from should you even come to that crossroad. Is peace of mind worth $3500 to you? Sounds to me that you do want coverage. I like risk, but this is a stupid risk to take on. Get the warranty, be done with it. You'll feel better.

Actually the 997 block is the same, as are the crank rods, heads, cams and intake manifolds. The only differences between the 997 engine and the 996 is different accessory routing, intake airbox and exhaust routing. Yes the rear main seal and clutch were revised on the 997, but those parts are now the current service replacements for the 996 through your Porsche dealer. The different intake box and ECU tuning are the differences for the minor 5 hp (but no torque) increase in the rating of the 997. Both the 997 Carrera and Carrera S use revised versions of the M96 transmission. The differences aren't to beef up the gearbox, but rather just re-gearing to compensate for the overall drive ratio change due to adding taller rear tires on the 997. They shortened all the gears so the overall drive ratio in every gear basically matches the previous 996. This is the primary reason why despite having slight more power and a slightly lower coeficient of drag, the 997 Carrera has the same gear limited top speed as the previous 996. The RMS is not going to cause an engine to blow up unless it is allowed to seap enough that the engine starves for oil (owner negligence). There were some production issues Porsche has admitted. In the early 2003 production, due to a faulty torque wrench many of the cars had timing chain tensioners that were improperly torqued and failed. Intermediate shafts and shaft bearing can also fail. This is ususally a slow process and is preceeded by an IMS leak. If it isn't fixed at the first sign of a problem, it can easily result in valves hitting pistons and an engine replacement down the line. Being intelligent and dealing with issues when they occur and not waiting can easily prevent a major issue down the line. so, not these cars are not ticking time bombs. That doesn't mean there aren't others out there that are. The 01-02' M3's really are a ticking timebomb. BMW designed an oiling system tht starves those engines at high rpms. They admitted and fixed the problem in 03'. Unfortunately, with an older can that has not had the issue corrected and is driven hard is just rolling the dice everytime on it blowing.

can you share more about detect Intermediate shafts and shaft bearing failure? from what i've seen (on the internet ) most time it just happend without any warning sign....

Porsche while not publicly saying so, is CONSTANTLY updating and changing things....the 3.4L for example has changed I think 10 times. This means that a 3.4L you buy now is FAR different from one sold in 2001....It contains all the updates incorporated in new 3.6 and 3.8 engines. So yes the 997 will be more reliable than the previous generation cars....but thats the way with any engine...as they are made more and they see what happens to them at higher mileage they can make changes...Remember the engine it replaced was updated for 40 years....its kind of amazing a new engine design can be made more powerful, cheaper to build and cheaper to maintain......so they did a pretty good job....

It is not a big deal as long as the car is still under warranty when it fails. While it won't cause engine failure, it is expensive to repair.

The 01-02 M3's are not ticking time bombs. The problems were not with the oil system, even though the oil pump was replaced with the connecting rod bearings on effected cars. By the way, the connecting rod bearing recall also effected most 03 cars as well. The majority of the cars effected were made from October 2001-February 2002. BMW changed the design for the connecting rod bearings during that period, which resulted in about 10% of the cars in that production range to have engine failures. In those cases, BMW replaced the engines. Most all 01-03 M3s were impacted by a service action to replace the connecting rod bearings. That seemed to solve the problem since there are very few reported cases of engine failures in cars with the replaced bearings. The incidence of failed engines in 04-06 M3's is close to zero, unless caused by driver error such as missed shift causing mechanical engine over rev. By the way, BMW issued a 6 yr./100.000 mile engine warranty to any owner with a M3 effected by the connecting rod bearing recall. Wonder if Porsche has done anything like that.

True enough, but it is now (apparently) a one time repair instead of a lottery.

Not in Porscheville You can get into much bigger tickets if you wait long enough.

Huh? Are you OK?

Yes An RMS replace is about $1,200 After 22 years of driving Porsches I would say that is cheap to get out of the stealer with. I have dropped multiples of 2,3,4,5,6,7,8 to that, many times over the years. Remember, if it was a Ferrari it would cost even more

A "ticking time bomb" that BMW has proactively taken measures to fully replace with proper parts and on top of it extended the original warranty for the engine - Porsche, what?

Such awesome engineering they've even made seemingly well educated folks bow at the throne of Porsche Myopia sacrificing their hard earned $ to actually justify their shortcomings. Do you guys really find it acceptable that Porsche's had so many tries at obliterating the RMS issue, yet to this day in 2007 they still remains instances of this stupid seal leaking? It's complete BS.

Gee, they are really great cars then.

Right! I am brain washed, I love these cars

The RMS is one small problem I do not consider an engine failure. Intermediate shaft failure, oil/coolant intermix, metal shavings in the oil, etc. All of these warrant a new engine, thus "engine replacement", and what I mean by engine failure. So if the consensus is that the 997 tweaks fixed this, did Porsche somehow get lucky in fixing it, or did they know how? That's sort of what I was getting at originally.